UNIVERSITY OF IBADAN LIBRARY
UNIVERSITY LECTURE
MANAGEMENT OF NIGERIAN SOIL
RESOURCES: AN IMPERATIVE FOR
SUSTAINABLE DEVELOPMENT
by
Ayoade Olayiwola Ogunkunle
UNIVERSITY OF IBADAN
2016
UNIVERSITY OF IBADAN LIBRARY
Ibadanuniversity Rm 
Publishing House 
University of Ibadm 
badan, Nigqia 
First MW 20f6 
AIIRighu ReJccrcd 
ISBN: m-978-5r1291-7-6 
P m d b y: I- University Printery 
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Vice-GhceIIorI D e p ~Vi ce-Chancellor (&hi- 
stration), Deputy Vice-Chancellor (Acocism*~R~~e gimr,  
Libmrian, Provosr of the College of Medicine, Dean of the 
Facufry of Agriculture and Forestry, Dean of the 
Postgraduate School, Deans of other +Faculties mad of 
Strcdents, Directors of Instirsltes, Distinguished Wits und 
Gentkrnen. 
Pmmble 
I hank the Almighty God and the University Management fur 
the privilege to deliver this lech~reo n W f of the Faculty of 
Agriculture and r;oreStry. I was reluctant at first when my 
Head of Dqarmmt muted the idea, but considwing tk fact 
thatXamaneof t h e f e w h t m i s s e d t h e ~ t y o f g i v i n g  
an inaugural lecture, l lam acceped the offer, mare 9o that it 
is  coming exactly one to my exit from the University. 
The mt in the series of university lectures from tfae 
F d t y  of Agriculture and RmsW was delivered by late 
hftssm V,A Oyenuga of the.Department of A n i d  
Science in the 1975n6 session. The main tide was, Wdqe, 
Rcsh,the Quality of Human ( i ) T h e H d q e a s  
SarPllts of Nutrients, (ii) Animal Flesh, Animal Products, the 
Quality of Life and (iii) Scientitic Educational Challenges in 
Food Agricultural M m Syste m. 'the second was by late 
Prof- QB.0. Anthonio from the then Ikpammnt of 
Agricultural Thmmics and Extension in 1983184. T h s ub 
titles of his lecture wae: (i) Nigerian Agriculture at th 
Croamds, (ii) Nigerian Agriculture Revisited, and (iii) 
Improved Agicuitml Marketing for Economic Development 
in Nigeria. The thixd was tsdvered by Rofessof Johnson 
Hqxxe of the then IXpammnt of Agricultural Extension in 
the 198911890 session. His lecatre was titled: "Agricultural 
Extension": (i) The Original Cotlcept. (ii) The Search, and 
(iii) The Bottomline. The fourth was by late Professor 
OlaOlu Babdola of the Departmiat of Agronomy--my 
Deparbmnt, in ZMW2Ml1. His lecture was title& 'Wigerian 
Agriculture": (i) Basis for Hop, (ii] Hurdles and against 
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Hope, and (iii) Hope for Tomorrow. My Lecture is therefore
the fifth in my Faculty and the second in my Department.
When I was asked to, submit the titles for the lecture, I
submitted 3 sub titles as was usually the case, but my Head of
Department came back to inform me that the University
Management, in its wisdom, had taken a decision to reduce
the University Lecture to only one part instead of three. I
believe that this decision must have been based on some
cogent reasons. Even then, I strongly feel that although five
lectures can be squeezed into one, the issues discussed in
university lectures deserve more attention and should be
given a longer time of presentation than the inaugural lecture.
This must have informed the original decision to make it
three lectures. Besides, there should be a difference between
the two; otherwise there may be no need for the university
lecture again. However, I believe there is a place for the
university lecture; therefore I wish to suggest that the new
decision be revisited for a consideration of at least two
partsllectures instead of only one.
The title of my lecture is: "Management of Nigerian Soil
Resources: An Imperative for Sustainable Development". It is
discussed under the following sub-headings: Man, Soil and
Development; Nigerian Agriculture; Nigerian Soil Resources;
Soil Degradation; Food Security; Soil Management and
Sustainable Development; Established Systems of
Sustainable Land/Soil Management; Conclusion and
Recommendations.
Man, Soil and Development
The challenges facing humanity globally are so enormous as
if human beings and the natural world are on a collision
course. Human activities inflict harsh and often irreversible
damage on the environment and on critical resources. If not
checked, many of man's current practices put the future that
we wish for human society and the plant and animal
kingdoms at serious risk, and may so alter the living world
that it will be unable to sustain life in the manner that we
expect. Natural resource depletion and adverse impacts of
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environmental degradation, including desertification,
drought, land degradation, freshwater scarcity and loss of
biodiversity, add to and exacerbate the challenges which
humanity faces. The situation is worsened by climate change
whose adverse effect on natural resources undermines the
ability of many nations to achieve sustainable development
(UN 2015).
Land is universal- and, according to the, Millennium
Ecosystem Assessment (MEA 2005), it is a major component
in all the four ecosystem services of Supporting,
Provisioning, Regulating and Cultural services. In an agrarian
economy, the land as a major factor of agricultural production
provides the needed fulcrum upon which sustainable
development would blossom. Soil is a component of land
resources and a major component of the ecosystem. It is the
real wealth of a nation as it is basic to human existence. Soil
is a vital and a non-renewable natural resource, on a human
time scale. It provides an essential interface between water,
nutrient and atmospheric cycles. Soil is essential for food,
feed, fibre and fuel production hence -it deserves to be at the
top of national and international agenda for its role in
sustaining life through food security. Soil provides many
other goods and ecosystem services, making it invaluable to
humankind. Unfortunately, in Nigeria, until recently, many
developmental policies and decisions leave out the soil as if it
does not matter or that it is optimally available and will
continue to be so.
Available data show that about 24% of the world's land
area is affected by degradation. Every year, 24 billion tons of
soil is lost due to wind and water erosion, construction
activities, compaction, resource extraction or exhaustive
cultivation, thereby impacting 1.5 billion people globally
(UNCCD Secretariat 2013). In the affected areas, land
degradation correlates closely with extreme poverty,
increased water scarcity, food insecurity and child mortality.
Inventories of soil productive capacity indicate human-
induced degradation on nearly 40% of the world's
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agricultural land as a result of soil erosion, atmospheric
pollution, extensive soil cultivation, over-grazing, land
clearing, salinization, and desertification (Oldeman 1994).
Indeed, degradation and loss of productive agricultural land is
one of our most pressing ecological concerns, rivalled only by
human-caused environmental problems like global climate
change, depletion of the protective ozone layer, and serious
.declines in biodiversity (Lal 1998). .
Global estimates of food-insecure populations stand
between 825 million (Lobell et al. 2008) to 850 million
(Borlaug 2007). Regional estimates of the food insecure
population include 263 million in South Asia (SA), 268
million in China and Southeast Asia, 212 million in Sub-
Saharan Africa (SSA), 60 million in South and Central
America and the Caribbean, and 50 million in other regions
of the world. Thus one of the United Nations' (UN)
Millennium Development Goals of cutting hunger by half by
2015 could not be achieved. The number of food-insecure
populations in the world is increasing and may continue to
increase. An estimated 75% of the world's poor « $2/day
income) live in rural areas and depend directly or indirectly
on agriculture (FAa 2006; LaI2009).
The challenges of food insecurity facing the society now
and over the next decades are mainly due to loss of soil and
water resources and associated ecosystem services, energy
security and climate change. There is a shortage of good
quality soil to bring about the desired increase in food
production (Lal 2009). Available data (e.g. Beinroth et al.
2001; Blum 2013) also show that lands of inherently high
quality (Class I) soils are uncommon globally. Such lands of
high quality soils with few limitations for crop production,
high response to management and capacity for high yield of
crops at minimal cost, occupy only about 2.38% of the global
land surface. On the other hand, land of poor quality soils
(with low moisture, low organic matter and plant nutrients,
poor physical properties and/or steep slope) occupies 45.30%
of the global land surface. The lands with soils that can be
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RY
adjudged fit (Classes I - IV) for agriculture (crop production)
occupy only about 15% of the global land surface (Blum
2013). The situation is not different in SSA and also Nigeria.
The ecosystem in most Sub-Saharan African countries is
seriously threatened through overuse/misuse. This is a direct
result of the increasing needs of a growing population, often
combined with inappropriate land/soil management practices.
Thus, on the one hand, the population is growing at over two
percent a year (FAO 2008), requiring a doubling of food
production by 2030 to keep pace with demand; on the other
hand, productivity of natural resources is in general decline.
Additionally, the number of natural disasters has increased
and climate change is already taking its toll. With the
alarming rate of population expansion, the competition
between agricultural and non-agricultural uses (urban,
industrial etc.) is becoming very stiff. Soil abuse, misuse and
pollutions combined with the negative effects of climate
change result in the high degree of soil degradation. Food
insecurity is the most obvious consequence of soil
degradation.
Sub-Saharan Africa (SSA) remains the only region in the
world where the number of hungry and malnourished
populations will still be on the increase even by 2020 (Rukuni
2002). While other regions have improved per capita food
availability since the 1970s, food production and availability
have perpetually declined in SSA. It is both a technological
and political/economic challenge, and cannot be ignored any
longer. Agrarian stagnation in SSA has defied numerous
attempts at transforming subsistence agriculture, even with
due consideration to issues related to biophysical constraints
and the human dimensions challenges (Otuska 2006).
Traditional agricultural practices in SSA have been addressed
in relation to soil degradation (Chokor and Odemerho 1994),
soil nutrients and SOM depletion (Stromgaard 1991; Dakora
and Keya 1997; Sanchez and Leakey 1997; Nye and
Greenland 1958), soil pests (Hillocks et al. 1996), pest
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management (Abate et al. 2000), and plant defense
mechanisms (van der Westhuizen 2004).
Sustainable development simply means all-round well-
being today and in the future. A hungry person cannot be said
to be well, hence food security is an important factor in
sustainable development. Thus, one of the Millennium
Development Goals (MDGl) was to "Eradicate extreme
poverty and hunger by the year 2015". Furthermore, 3 (Goals
2, 3 and 15) of the 17 Sustainable Development Goals that
replaced the MDGs at the end of 2015 (emphasize' ending
hunger, promotion of well-being and ecosystem preservation
and sustainability respectively hnps.r/sustainabledevelopment,
un.org/sdg sproposal. htm).
Obviously, there cannot be any true development in the
face of poverty and hunger/food insecurity and degraded
ecosystem. An important means to eradicate hunger and food
insecurity (and thus achieve sustainable development) is to
manage soil resources in a way that avoids all forms of
degradation or at least reduce it to the barest minimum. The
thin layer of soil covering the surface of the earth represents
the difference between survival and extinction for most land-
based life (Doran et al. 1996). Management of soil
encompasses a wide range of practices with the' express
purpose of improving the capability of the soil to perform its
various functions.
The quality of soil is impaired as soon as it is opened up
for use or exposed to unfavourable climatic conditions. The
highly efficient old traditional soil management system of
shifting cultivation/bush fallow system (Nye and Greenland
1960) can no longer be sustained because of shortage of land
space resulting from population explosion and competition
from non-agricultural land uses. Fertilizer applications as
currently practised by most Nigerian farmers are not based on
soil data, and can do more damage to the crops some time
later. Embracing science-based soil management practices
that directly respond to these challenges is crucial, essential
and urgent for the long-term sustainability of soil resources in
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the performance of their functions, among which food
security is major. The intent of this lecture therefore, is to
draw the attention of Nigerians, particularly policy makers,to
the fragile nature of the soil resources of Nigeria, the high
degree of soil degradation to which the soils are subjected and
the combined negative impact on arable crop yield/food.
production. Hence, the urgent need for the adoption of
. appropriate management packages and actions that sustain .
soil quality, arrest food insecurity and enhance sustainable
development in the country.
Nigerian Agriculture
Agricultural development in Nigeria has evolved through a
long history bedevilled by many constraints which restrict the
sector's growth and productivity. In the 1960s, Nigeria was
mainly an agricultural economy. It was among the world's
leading producers of Cocoa, Palm oil, Groundnuts, Cotton,
Rubber, and Hides and' Skin. The agricultural sector
contributed over 60% to the Gross Domestic Product (GDP),
supplying 70% of export and 95% of food needs. Despite its
current reputation as petroleum resource dependent, Nigeria
remains an agrarian economy, with between 60 and 70% of
the population productively engaged in farming (Ukeje 2003;
Nwajiuba 2010).
Nigeria has about 79 million hectares of arable land, of
which 32 million hectares are cultivated. Over 90% of
agricultural production is rain-fed. Smallholders, mostly
subsistence producers account for 80% of all farm holdings.
Crop production remains below potentials partly due to
inadequate access to high quality seeds, low and/or
inappropriate fertilizer use and inefficient production
systems. Despite a 7% growth rate in agricultural production
(2006-2008), Nigeria's food import bill has risen. The
growing population is dependent on imported food staples,
including rice, wheat and fish. Nigerian agriculture contri-
butes, to a small extent, to global warming through bush
burning and other poor land management practices.
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Before the discovery of oil, agriculture was the main
income earner of Nigeria in terms of GDP, foreign exchange,
and employment of labour. The Federal Government
established several agricultural policies and/or programmes.
These include: Farm Settlement Scheme, World Bank:
assisted Agricultural Development Programmes {ADPs},
Crop Research Institutes (increased to 18 in 1977), Marketing
Commodity Boards (7) for various crops, River Basin
Development Authorities (RBDAs), Nigerian Agricultural,
Cooperative and Rural Development Bank (NACRDB),
Agricultural Credit Guarantee Scheme Fund (ACGSF) and
Federal Agricultural Coordinating Unit (FACU).
Between 1975 and 1983, Government established the
National Accelerated Food Production Project (NAFPP).
National Grains Production Company, National Livestock
Production Company, Nigerian Food Company, National Fish
Production Company, etc. In 1976" Government launched
Operation Feed the Nation (OFN) and in 1980, OFN was
replaced with the Green Revolution and Directorate of Food,
Roads and Rural Infrastructures (DFFRl). However, all these
efforts to revamp agriculture had little, if any effect on the
development of the agricultural sector, the major determinant
of the Nigerian economy mainly because the efforts were not
pursued with sincerity of purpose. The projects were not
funded and many were abandoned within 2 or 3 years of their
existence; this resulted in the neglect of the agricultural rector
by the Federal Government and the concentration on oil
(Izuchukwu 2011).
Apart from the abandonment, the handling of agricultcre
before and after the oil 'boom' showed •rn abnost total nelt~~·
01' tne role of soil resources in agricultural production ..
Knowledge about the nation's oil resources was rudimentary
and the impact of soil conditions on crop performance was
taken for granted. Crop production system did not include any
serious soil management apart from the old practice of
shifting cultivation invented by the traditional small-holder
farmers based on their experience in the field (Nye and
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AN LIBRARY
Greenland 1960). Inorganic fertilizer application was the only
soil chemical fertility management practice that was available
to farmers for a very long time. Even then, the fertilizer
applications were done haphazardly on 'blanket' basis and
were never based on results of soil analysis or soil test.
There seemed to be an erroneous assumption that
Nigerian soils have the unconditional capacity to support high
crop production for as long ,as was required, even among
intellectuals in the agricultural profession. Let me illustrate
this with my experience with a colleague in my Faculty in
1991. He was approachedby a farmer for feasibility study for
a 250 ha fruit orchard in a village in Ogun State, and invited
those of us that he considered relevant to the study. He then
showed us the costing where he allocated about 80% of the
fund to market survey (for a product for which we were not
sure whether the location was suitable or not). He allocated
the remaining 20% to soil and other studies, so soil could not
even have up to 20% of the fund. So, if a colleague
agriculturist can do that, then the neglect of soil resources by
policy makers should not be a surprise.
The first time that serious consideration was given to the
importance of soils in agriculture was in 1951 when the
\'.{!e:!l~rnRegion Government commissioned its Department
of Agricultural Services, Research Division (now IAR & T)
to conduct the soil survey of the Central Western Nigeria for
Cocoa cultivation. The results of the soil survey are contained
in a publication which has served as a soil manual for soil
scientists within and outside the region (Smyth and
Montgomery 1962). Around the same time, similar actions
were taken in the then Northern and Eastern Regions
(Klinkenberg and Higgins 1968; Jungerius 1964). In the
Western region, the results of the soil survey were also used
for the allocation of the Farm Settlements according to the
kind and potentials of the soils.
The Federal Government showed very little concern for
soils in agriculture until 1980 when it established the Federal
Department of Agricultural Land Resources (FDALR) in the
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Federal Ministry of Agriculture and Natural Resources with a
School of Soil Conservation. The Department was established
for detailed and accurate inventory of Nigerian soil resources
and their characteristics, classification, capacity for the
various crops and appropriate management for optimum crop
production. In 1992, with further realization of the unique
role of soils, in terms of information on its characteristics and
the impact of soil loss on agricultural (crop) production, the
National Agricultural Land Development Authority
(NALDA) was created from FDALR to conduct soil surveys
for agricultural projects and handle all land development
projects. But NALDA was scrapped in 1999, seven years
after its establishment.
One major negative consequence of the neglect of soil
resources is that, at the moment, Nigeria does not have a
National Soil Classification system. This is a clear indication
that the importance of soil resources to agricultural
production is not appreciated by the policy makers. It was in
1990 that FDALR, with the assistance of the United States
Department of Agriculture (USDA), produced the first soil
map of Nigeria based largely on geomorphological/soil order
units of the USDA Soil Taxonomy (FDALR 1990).
Obviously, this map cannot achieve much in view of the very
broad units of mapping, and this is confirmed by field and
cartographic evaluation (Olaniyan and Ogunkunle 2007a& b).
The predictive value and utility of this map cannot be high
because it was not based on the soil classes identified on the
Nigerian soil classification system. The level of the USDA
soil classes employed is too broad that it cannot be
appropriate even for land use planning.
Agriculture Transformation Agenda
The Agriculture Transformation Agenda (Vision 2020,
NTWG 2009) of the Federal Government from 2011 to 2014
was a success story because government decided to do things
differently from the old practice and had a focussed,
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committed and convicted person to drive it. Government
decided to:
(A) Stop doing certain things: (i) Treating agriculture as
a development project, (ii) Spending on projects that
do not clearly grow the sector in a clear and
measurable way, (iii) Big government crowding out
the private sector; arid,
(B) Start doing certain things: (i)Treating agriculture as a'
business; (ii) Integrating food production, storage,
food processing and industrial manufacturing by
value chains ('farm to fork'); (iii) Focusing on value
chains where Nigeria has comparative advantage;
(iv) Using agriculture to create jobs, wealth and
ensure food security; (v) Investment-driven strategic
partnerships with the private sector; (vi) Investment
drives to unlock potential of the States in agriculture
(joint drives with State Governors).
The outcome of these efforts is well known to all, including:
• Rebirth of local fertilizer industry;
• Employment opportunity;
• Higher crop yield (cassava, rice);
• Commercialized cassava bread industry;
• Youth showing interest in agriculture;
• Emergence of food crop processing centres (14).
The Agricultural Transformation Agenda recognized the
importance of soil resources to the success of crop
production. This is confirmed by the fact that, for each of the
value-chain crops (including cash crops), soil studies were
commissioned for the locations of interest. Even then, this is
only a temporary measure. There is no alternative to a
comprehensive soil survey of the country for data on soil
types, their extent, characteristics and potentials. Due
consideration must be given to sustainable environmental
(land/soil and water) management to guide fertilizer
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application and other cultural practices that may be required
for optimum crop performance. Soil quality involves far more
than chemical fertility.
The Nigerian Ecosystem
Nigeria is characterized by a very rich diversity of natural
ecosystem resoiaces, including soils, vegetation, watersheds
and genetic diversity. Together, these constitute the nation's
main natural capital. It is from these assets that the provision
of food, water, wood, fibre, industrial products, and essential
ecosystem services and functions are derived. It is from the
land that over 60% of the people directly derive their
livelihoods (FAO 2004). The key factors of the ecosystem
that have strong impact on agriculture are climate and soil.
The Nigerian climate is sub-tropical/tropical to semiarid with
rainfall decreasing from the south (400 cm/yr.) to the north
(75 em/yr.). Pan evapotranspiration ranges between 1632 mm
in Port Harcourt and 3512 mm in Kano. Length of dry season
ranges between about 120 days in Port Harcourt to about 300
days in Kano. The high variation in climatic conditions across
the country has produced 8 agro-ecological regions (fig.l)
with different vegetation and adaptive crop types. In addition,
marked climatic changes in the last three. to four decades have
resulted in desert encroachment (advancing at the rate of 0.6
km/year (FADE 2013) from the Sahara, threatening
agriculture in the north while rainfall in the south is becoming
erratic and unpredictable.
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I·----==:T""';::------------- .-.J~-l~ i1
I
_Oer~~MN
_1iIg~..waoe
_HlJI'!'id!'OtHt
_"';,,:~ 1
.• !'to$ei'l'l c.~1t-a s.....•MI !
Semo.kidIS~~ •.~•...• ;
_~Gui!lN~\'II'$i
e ~s ,~ _\'h.tI::!:Io6t!1.
I, ! • ! , , , !
Fig. 1: Agro-ecological regions of Nigeria (UTA).
Nigerian Soil Resources
Underlying Geology, General Description and Distribution
of the Soils
Available information (Moorman 1981; Ogunkunle 1986;
Ogunkunle and Babalola 1986; Ogunkunle 2009; Esu 2005)
shows that at least six (6) of the soil Orders of the USDA Soil
Taxomy (8 of the WRB major Soil Groups of the FAO
System) are found in Nigeria. They include: Alfisol, Ultisol,
Entisol, Inceptisol, Vertisol and Andisol. The northernmost
part covering about 15% of the country is occupied by
Aeolian deposits from which immature, weakly developed,
sandy Entisols (Regosols/Arenosols) have been formed. The
most extensive geological deposit in the country is the Pre-
Cambrian Basement Complex. It is made up of metamorphic
and igneous rocks and covers a substantial portion of the
southwest, southeast and the middle belt areas. The major
soils on this deposit are the deep low activity-clay (LAC)
Alfisols (Luvisols, Nitosols) at the upper and mid-slope
positions, the shallow, rocky Entisol (Lithosols) at the crest
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and the sandy, deep, hill wash Entisols (Regosol/Arenosols)
at the lower slope/valley positions. Sandstone deposits occur
in the middle belt, immediate north of Rivers Niger and
Benue, while the Coastal Plain Sand deposits extent from the
southwest, extending through the mid-west to the southeast.
Alluvial deposits are along Rivers Niger and Benue and the,
Niger Delta: . ,
The soils on the Sandstone and Coastal Plain Sands are
low activity-clay (LAC) Ultisols (Acrisols). with Inceptisols
(Cambisols) and Entisols (Arenosols) occupying the lower
slope and valley positions. The soils of alluvial deposits
consist of immature and weakly developed Inceptisols
(Cambisols) and Entisols (Regosols/Arenosol). Vertisols
occur in limited amounts in the north eastern corner and the
north of Benue River and around Lake Chad. Andisols are
volcanic soils limited to the Jos Plateau area (fig. 2). More
detailed information on these soils is provided in the next
section while their major characteristics are summarised in
table l. Typical profiles of some of these soils are shown in
figure 3.
15"O'O'E
Fig. 2: Generalized soil map of Nigeria.
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Table 1: Some Characteristics of the Major Soils of Nigeria
Soil Land Coverage Parent Clay BulkDensity Surface pH
OM ECEC (cmol
Order (Approx. %) Material Mineralogy (gkg") l(gcm-3 Texture' (H O)) 2 (surface) kg- ) (subsoil)
Alfisol 35 Basement LAC 1.2-1.8 Loamy 5-6.5 1-3 10-20
Complex (BC) Kaolinite, sand/Sandy
Sesquioxides loam
Ultisol 30 Sandstone, LAC, 1.2-1.8 Loamy 4-5.5 1.5-3 10-20
Coastal Plain Kaolinite, sand/Sandy
Sand, Shale Sesquioxides loam
Entisol 15 Flood Plain, Kaolinite, Loamy 6-7 2-8 10-25
BC, Sandstone, Quartz sand/Sandy
Coastal Plain loam
Sand
Inceptisol 10 Flood Plain, Kaolinite, Loamy 6-7 2-8 10-25
BC, Sandstone, Quartz sand/Sandy
Coastal Plain loam
Sand
Vertisol 5 Shale, Basalt, Smectite, Clay 6-8 0.2-1 20-50
Clay, Alluvium Kaolinite, (CECpH7)
Illite
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FromAkwa~bomState FromOyo State From EdoState
Fig. 3: Typical soil profiles from some locations in Nigeria.
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Alfisols and Ultiso!s (Luvisols/Nitosols and Acrisols)
Alfisols and Ultisols are soils with clay accumulation in the
sub-soil. The two soils together constitute about 65% of the
soils in Nigeria. They are deep to fairly deep soils with loamy
sand/sandy loam surface, increasing in clay content with .
depth to sandy clay loam/sandy clay or clay. The two soils
occur in the savanna and rainforest ,regions. Alfisol is more·
predominant on Basement ,Complex while Ultisol is more on
Sandstone/Coastal Plain Sand/Shale. Presence of argillic
horizon (clay accumulation) is diagnostic for both soils.
There is great variation in colour; from lOYRJ7.5YR hu~ in
the surface to 5YRJ2.5YRJlOR in the lower depths. Alfisols
often contain Fe-Mn concretions/nodules in the subsoil at
about 80-120cm. In the rainforest and guinea savanna regions
the concretionary layer at this depth is prominent and has
been referred to as stoneline (Ahn 1970). Some Alfisols in the
rainforest region (e.g. Egbeda and Olorunda series) contain
characteristic light red (2.5YR6/8) pedogenic "mottles", even
though they are well drained. Ultisols are generally less
gravelly except in locations with high degree of fluctuations
of water-table where plinthite is formed. The profiles are
more uniform in colour, especially when well drained.
Both soils have low bulk density. The initial soil structure
is good, crumb (under rainforest) or subangular blocky (in the
savanna) due to flocculation/cementation of clay by organo-
mineral complexes to form stable aggregation. However, the
soil structure easily breaks down once the vegetation is
removed for cultivation. This makes them susceptible to
erosion. Soils in regions with prolonged dry-seasons are
desiccated up to about 1m depth, being subjected to high
temperature extremes when at low moisture content. The soils
are thus prone to developing surface seals and crust formation
with low water-transmission properties. They are very deep
(~200cm) although the effective rooting depth in some upper-
slope Alfisols is shallow « 100cm) due to adverse soil
physical properties (Vine et al. 1981; Babalola and Lal 1977).
Most upland with low-activity clay (LAC) soils have low
plant-available water reserves and are generally less than
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lOcm in the root zone. Consequently, seasonal crops are
prone to periodic drought stress throughout the growing
season (Lal 1986). .
Alfisols are less acidic (pH of S-6+) than Ultisols (pH of
4-S+) and the acidity increases with movement from the
savanna to the forest regions. Both soils are low in organic
matter, nitrogen, available phosphorous and exchangeable
cations (Ca, Mg, K and Na), and cation exchange capacity
(CEC). The Ultisols are lower in these nutrients than the
Alfisols.
Entisols and Inceptisols (Regosols/ Arenosols and
Cambisols)
These are young (at early stage of development) soils, but
Entisols are younger and less developed than Inceptisols.
Both of them occur on all the parent materials and agro-
ecological zones, particularly in sand dunes, coastal deposits,
flood plains in lower slope or valley bottom positions and
shallow, rocky terrains. Entisols have not developed to the
stage of having diagnostic subsoil (B) horizons, but
Inceptisols show structural development (Cambic horizon) in.
the subsoil. The sand dune Entisols (Psamments) are very
deep with single grain structure in the upper 1O-20cm layer of
sand/loamy sand texture. The texture can be loamy sand
down to a depth of lS0-200cm, but can change to sandy loam
at this depth in others (FDALR 1990). Similar profiles occur .
in alluvial deposits along river courses (e.g. Niger and Benue)
and the Niger Delta except that in the latter, organic matter
content is higher and decreases irregularly with depth.
Entisols constitute about lS% and Inceptisols about 10% of
the soils in Nigeria (Ogunkunle 1986; Esu 200S).
Generally, sand dune soils are very low in plant nutrier ts
while most flood plain soils are very high in plant nutrier.ts
(N, P, K, Ca and Mg) as a result of high organic matter (Esu
and Ojanuga 1989). The sand mineralogy of dune soils is
dominated by quartz while the clay mineralogy is dominated
by kaolinite and quartz. Some amount of smectite occurs in
the clay fraction of poorly drained Aquepts and Aquents.
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Vertisols
These are heavy black clayey soils associated with calcium
rich parent rocks and relatively dry savanna climate. They
occur in the north-eastern part of Nigeria around Lake Chad
(Esu 2005), notably Bornu, Yobe, Adamawa and Bauchi.
They constitute about 5% of the soils of Nigeria. They are
characterized by a very heavy texture with montmorillonite as
the dominant clay fraction, usually with free calcium
carbonate which forms concretions in the sub-horizons. They
are derived from diverse parent materials including lacustrine
clay deposits, olivine basalt, ancient alluvial deposits and
ancient marine shales. They crack on drying and are difficult
to cultivate because of their stickiness when wet and hardness
when dry. Although reserves of weatherable minerals are
often high and the exchange complex is well saturated with
cations, the nutrient status of vertisols is rarely balanced
(Jones and Wild 1975). They are underutilized because of
poor understanding of their management (Ahmad and
Mermut 1996).
Andisols (Andosols)
These are soils formed from materials of volcanic ongm.
They occur in the Jos Plateau. They were classified as
Inceptisols (Andepts) in the USDA, Soil Taxonomy until
recently. The soils have high organic matter and low bulk
density, appreciable amount of allophane of high exchange
capacity. They are dark brown on the surface and yellowish at
depth. They have relatively high silt and (amorphous) clay
content. The consistency is greasy but neither sticky nor
plastic. Andisols have a high agricultural potential. They have
high available water capacity and are freely drained except
when silcrete is present. The natural fertility is high. Together
with other soils (e.g. organic soils-Histosols) they constitute
< 5% of the soils in Nigeria.
Dryland (Arid) Soils
By and large, the drylands are dominated by Aridisols,
Alfisols Calcisols and Histosols; Aridisols being the most
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common soils. They have been observed to be devoid of
vegetation for 7-8 months of the year outside of the rainy
season. In Sokoto, they have been described as soils having
high sand content at the surface, formed on aeolian sand
cover with low organic matter content (~2%) (Sharu et al.
2013; Landon 1991), which Yakubu (2001) attributed to
factors such as continuous cultivation, frequent burning of
farm residues commonly carried out by farmers in the area, a
practice that tends to destroy much of the little organic
materials that could have been added to the soils. Agbu and
Ojanuga (1989) associated the low soil fertility of the
drylands to rapid decomposition and mineralization of
organic materials contributed by sparse vegetation in the hot
semi-arid climate, promoted by high solar radiation (Noma et
al. 2011).
Wetland (Fadama) Soils
In fadama land, the common soil types are: Entisols,
Inceptisols, Vertisols and Mollisols. Their physical features
are good surface conditions and higher clay/silt content
compared to those in the dry land. In a study of fadama soils
in Sokoto, Singh and Babaji (1990) described the soils as
poorly drained (Gleysols) and texturally finer and
nutritionally richer than the surrounding upland soils. Soils in
back swamps are poorly drained (GleysolslFluvisols)
especially in the rainy season; hence they are mottled in the
subsoil (and in some cases from the surface). They are highly
variable in texture, colour etc., laterally and with depth.
Generally, fadama soils retain a high level of moisture in any
season of the year and are therefore more suitable for many
forms of agricultural production, especially lowland rice,
vegetable and horticultural crops and some other cultivated
crops, all-year-round.
Capacity of Nigerian Soils for Crop Production
There is a lot of misconception about the capacity of Nigerian
soil resources for crop production. Such statements as
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"Nigeria is blessed with vast expanse of fertile land for
agriculture" (Aribisala 1983) are very common among
politicians and policy makers. Available information
(FAOSTATS 2005; Hartrnans, 1984; Ogunkunle, 1987, 1988;
Lal 2009) however, shows that Nigerian soils are very fragile
and cannot sustain crop productivity for more than one or two
years (cropping) after the land is opened up from natural
vegetation. This is mainly because of the clay mineralogy of
the soils which is dominated by low activity clays (LAC),
mainly kaolinite and oxides and hydrous oxides of iron and
aluminum (Hughes 1978; Juo 1979). Thus, the nutrient
holding capacity of the soils depends almost exclusively on
the soil organic matter (SOM) which gets mineralized very
fast under intense solar radiation and cultivation. This
explains the rationale behind the practice of shifting
cultivation/bush fallow whereby farmers abandon the plot
after 2-3 years of use (to allow it recuperate through
vegetation growth and organic matter accumulation) and
move to a fallow land or open up a new plot.
Contrary to the belief by many Nigerians, data from
practical farming and research (e.g. Ogunkunle 1981, 1989;
Ogunkunle and Akoroda 1992) show that the capacity of
Nigerian soils for crop production ranges between marginal
and low (tables 2 & 3). The data on the tables emanate from
research studies on soils in the northern and southern parts of
the country. Table 1 reveals that by Land Capability
Classification system (LCC), only 8% of the soils have high
potential, 4-31 % are moderate and 26-64% are marginal. In
table 2, the Land Suitability Evaluation (LSE) system shows
that 16% of the soils have high potential for maize, 30-50%
are moderate and 25-45% are marginal. The FAO Statistics
(table 4) confirms these two results. It shows that none of
Nigerian soils has high capacity for crop production, 5.5% are
moderate, 46.5 are marginal and the rest (48%) are low.
These data reinforce the fact that Nigerian soils are fragile
and require careful, data-based management for optimum
crop production.
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Table 2: Land Capability Classification of Nigeria Soils
Proportion (%) in Capacity Class Size of
I II III IV V VI VII VIII Area
Location State (ha)
ARABLE NON-ARABLE
Oyo Oyo 26 52 10 12 5,000
10s Plateau 22 .26 2.5 5 22 12,000
Odogbolu 'Ogun 31 43 20 5 2,900
Benue Benue 8 4 64 12 5 80,000
Flood
Plain
Table 3: Land Suitability Evaluation (LSE) of Nigeria Soils
Location State Proportion (%) inSuitability (Maize) Class Area Size (ha)
SI S2 S3 Nl N2
Yenegoa Bayelsa 50 45 5 80,000
Niger Niger 16 30 25 21 8 3.200
Basin
Kano Kano 33 45 22 2080
Table 4: Productivity of Nigerian Soils (FAO Statistics)
Soil Area
Productivity FAO Soil Classes
Grade km2 % of total
High (1)
Good (2) Fiuvisois, Gleysois, Regosois 50.4 5.52
Medium (3) Lixisois, Cambisois, Luvisois, 423.6 46.45
Nitosois
Low (4) Acrisols, Ferrasols, Alisols, 289.2 31.72
Vertisols
Low (5) Arenosols, Nitosols 148.8 16.32
Source: FAOST ATS (2005)
A major consequence of the marginal-average quality of
Nigerian soils is the relatively lower yields of crops compared
to their potentials under good management. Wudiri and
Fatoba (1992) showed that the gap between the yields of most
of the cereals and tuber crops in Nigeria compared to their
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potentials is 25 - 400% (table 5). This shows again and very
clearly that the role of soil management in crop production
cannot be taken for granted. Even with the most high-yielding
hybrid crop variety, unless the soil condition is conducive in
terms of the physical, chemical and biological characteristics,
the potential of the crop cannot be attained. All the
investments of several years of research, breeding, fertilizer
application, weed and pest control etc. will continue to be a
waste when due consideration is not given to adequate soil
management.
Table 5: Average and Potential Yields of Cereal and Tuber
Crops in Nigeria
Crop Average Yield Potential Yield(tons/ha) (tons/ha) Gap (%)
Cereals
Upland Rice 0.8 - 1.2 1.5 - 2.5 88-108
Lowland Rice 1.0 - 2.0 2.5 - 8.0 50-300
Maize 1.5 - 2.0 3.5 - 10.0 133-400
Sorghum 0.5 - 1.2 2.0- 2.5 108-300
Millet 0.5 - 1.0 1.0 - 2.0 100
Tubers
Cassava II -12 20 - 25 82-108
Cocoyam 5-6 8 - 10 60-67
Irish Potato 10- 12 14-15 25-40
Sweet Potato 10-12 14-15 25-40
Yam 12-14 18 - 20 43-50
Source: Wudiri and Fatoba (1992)
Soil Degradation
There is a growing recognition, among both policy-makers
and soil specialists, that soil degradation is one of the root
causes of the declining agricultural productivity in Sub-
Saharan Africa (SSA) and that, unless controlled, many parts
of the continent will suffer increasingly from food insecurity
(Lal 1990; UNEP 1982). Soil degradation is the decline in
soil quality caused by natural factors or, more often, by
improper use/management, usually for agricultural, pastoral,
industrial or urban purposes. Soil degradation may be
exacerbated by climate change and encompasses physical,
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~ chemical and biological deterioration. Examples of soil
degradation are erosion by water or wind, loss of organic
matter, decline in soil fertility, decline in structural condition,
topsoil loss, and adverse changes in salinity, acidity or
alkalinity. toxicity by chemicals, pollutants and excessive
flooding (Charman and Murphy 2005).
Soil degradation has three kinds of consequences on the
ecosystem/ecosystem services; (1) Ecological, (ii) Economic,
and (iii) Social consequences (Douglas 1994). Ecological
consequence is the most obvious; it includes soil loss; 'loss of
crop yield, biodiversity, forest and other land resources. Each
ecological consequence has associated economic and social
consequences. For instance, loss of crop yield (ecological) if
not checked, can lead to poverty (social) and poor financial
capability (economic), e.g. low contribution to GDP. The
most critical ecological consequences are soil erosion, loss of
soil organic matter, soil .nutrient depletion and loss. of
biodiversity (UNEP 2013).
Lack of information and basic knowledge of soil
degradation and the characteristics of soil resources are major
obstacles against reducing land degradation, improving
agricultural productivity, and facilitating the adoption of
sustainable land management (SLM) among Nigerian
smallholder farmers (Liniger et al. 2011). The soil
degradation process occurs in the following way: soil crusting
and sealing, compaction of the surface soil, reduction of pore
spaces and infiltration, low water-holding capacity,
accelerated runoff resulting in severe erosion, decline of soil
organic matter (SOM), decrease in pH, and nutrient
imbalance. Erosion by water or wind is the most severe kind
of soil degradation in Nigeria. Leaching of essential plant
nutrients out of the root zone is also very severe in sandy
soils, occurring in areas with heavy rainfall particularly in
eastern Nigeria. The major factors of soil degradation in
Nigeria are: expansion of area cultivated for agriculture,
overgrazing, deforestation, population expansion, poverty,
climate change, oil pollution and soil excavation/quarrying.
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With the exception of oil pollution and quarrying, all the
other factors are related to each other.
Water erosion poses the greatest threat to Nigerian soils
and affects over 80% of the land (NEST 1991). Wind, sheet,
gully and beach erosion affect different parts of the country at
varying intensities. While erosion by wind is confined to the
arid north, erosion by water is ubiquitous throughout the
country. Areas most prone to sheet erosion are plots where
farming has cleared the original vegetation, and the land
became impoverished 'scrubland. Gully erosion is by far the
most alarming type of erosion in Nigeria, particularly in the
eastern region, because it often threatens settlements and
roads. Although it affects a small fraction (less than 0.1%) of
Nigeria's 924,000 km2 of landmass, gully erosion claims
large amounts of public funds annually for remedial action.
With continuous increase in population, there is increased
demand for food requiring increased food production. This
has been achieved mainly through expansion in the land area
cultivated and very little from intensification i.e. increased
yield per land area (Ogunkunle 2015a). The expansion of area
for farming leads to shorter fallow period, the use of very
fragile areas and the use of fire for land clearing, all of which
reduce organic matter in the soil. Overgrazing causes soil
compaction and reduced resistance to drought, although it is
mainly restricted to the northern part of Nigeria.
Deforestation has been caused by expansion of farming,
housing needs due to population expansion or use of wood for
energy due to poverty. Climate change is a major cause of
desert encroachment and various unpredictable soil degra-
dation activities. Oil pollution occurs in the oil producing
regions of the south. It affects soil biological, chemical and
physical processes negatively, particularly soil nutrient
movement and organic matter mineralization. Indiscriminate
quarrying is found all over Nigeria. This has resulted in gully
erosions that have consumed houses and even entire villages,
particularly in the eastern regions with generally sandy soils.
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Soil degradation, particularly erosion, has assumed a
serious dimension in Nigeria, affecting every part of the
country (table 6, figs. 4 & 5). Soil erosion in the south-eastern
part of Nigeria has been identified as the most threatening
environmental hazard in the country (Abegunde et al. 2006).
Secondary data on the study traced its origin to some 30 years
ago when development began to creep into the region,
following Nigeria's oil boom of the 1970s. Dugout pits,
created from soil excavation activities, for foundation filling
and sand for brick making and plastering of buildings
produced deep craters and gullies due to perennial erosion
from torrential tropical rains. The sandy nature of the geology
of the area has worsened the situation. This, happening over
many years, and not well managed had resulted to gullies,
found in more than 1000 sites with over 700 of them located
in Anambra State alone. Erosion has ravaged much of the
vast lands in south-eastern Nigeria so much, resulting in
active and inactive gullied surface areas with lengths ranging
from 0.7 km in Ohafia to 1.15 km in Abiriba in Abia State.
The widths of the gullies range between 2.4 km for Abiriba
and 0.4 km for Ohafia.
Table 6: Erosion Types and Coverage in Nigeria
No. of States
Type of Erosion Intensively affected States
affected
Ogun, Kwara, Oyo, Benue
Sheet 19
Gongola, Imo, Anambra
Imo, Anambra, Plateau, Cross
Gully 6 River, Borno, Bauchi
Rivers, Cross River, Lagos,
Coastal 5 Edo, Delta
Rill 4 Plateau, Anambra, Lagos, Imo
Surface-mining 3 Plateau, Anambra, Kwara
Source: Ogunkunle (2009)
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Fig 4: An erosion site in Auchi, Edo State.
Fig 5: A gully erosion site in Abiriba, Abia State.
Further, a depth of 120km gullied surface has been recorded
at Abiriba (Ofamata 2001). Also, the problems of widespread
sheet wash erosion explain the failure of agricultural
activities. This is why soil erosion is a stress on soil resources
with some far-reaching consequences on man and his
environment (Jimoh 2000). In the northern axis of Nigeria,
erosion is equally serious, especially in places like Shendam
and WesternPankshin in Plateau State, Ankpa and Okene in
Kogi State. Sporadic rainfalls in 1994 rendered people
homeless in Kastina State, while properties worth over 400
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million naira (apart from lives) were lost. Gullied erosion is
also prominent in Efon-Alaaye, Ekiti State in the western part
of the country (Adeniran 1993).
Degradation of Soil Physical Properties
Erosion is a three-step process involving the detachment,
transportation, and deposition of soil particles. All these three
take place through a medium, which may be water or wind.
The most common soil erosion however, is driven by rainfall
erosivity i.e. the potential of rainfall to cause erosion.
Detachment of individual soil particles may occur when
raindrops strike the surface and overcome the forces holding
the soil particles together. This is referred to as rain splash
and it involves dislodgement of soil particles from the
surface. When the rainfall rate and amount exceeds the
combined interception by vegetation cover and the infiltration
capacity of the soils, water begins to accumulate on the soil in
micro-depression. If it continues to rain, the water eventually
flows on the surface as runoff or overland flow. Runoff on
slopes acts as a transporting agent, carrying away the
dislodged soil particles.
Research has shown that there is significantly more sand
in eroded soils than non-eroded soils (table 7). This is as a
result of the loss of organic binding agents by rain action,
leading to the loss of finer soil particles carried away by the
force of erosion and flood water (Olusegun et al. 2011).
Soil erosion selectively detaches the colloidal fractions of
soils and carts them away in runoff. These soil colloidal
fractions (clay and humus) are needed for soil fertility,
aggregation, structural stability, and favourable pore size
distribution (Babalola 2007; Crosson 1995). The
concentration of humus is usually higher in topsoils while
that of clay is usually higher in sub-soils due to illuviation,
and this is mostly true in Ultisols and Alfisols that constitute
about 70% of the soils in Nigeria (Esu 2005; Ogunkunle
2010). Increased soil erosion promotes soil compaction
(Mainville et al. 2006) and loss of weakened top layers of soil
(Fare IIa et al. 2001) especially in agroecosystems
characterized by high rate of deforestation.
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The aggregate stability of soils is reduced by erosion,
especially the 2.0 mm fraction. Total, micro- and macro-
porosity are also significantly lower in eroded than in non-
eroded soils (Uwanuruochi and Nwachukwu 2012).
Generally, silt and clay contents in eroded soils are lower
while sand content is higher, suggesting great influences 'on .
.surface water flow, which have eroded the lighter silt and
clay in the soils (table 7} Thus, through erosion, ,soil
structural indices are adversely affected as total porosity,
hydraulic conductivity; infiltration and aggregate stability are
all lower in eroded soil (Uwanuochi and Nwachukwu 2012).
Reduced water infiltration tends to increase runoff which can
lead to further erosion, and lower soil porosity has
implications for reduced aeration and consequently,
productivity. A reduction in the silt and clay fractions of the
soil tends to also cause lower chemical reactions and
exchangeable cations due to loss of topsoil which reduces the
capacity of soil to function and restricts its ability to sustain
future uses. Destruction of the physical characteristics of the
soil through erosion will limit even the other uses of the land
like urban and rural infrastructural developments.
Table 7: Effect of Erosion on Soil Particle Size
Non-Eroded Soils Eroded Soils
Location Sand Silt Clay Sand Silt Clay
glkg glkg
Isiukwuato 90,56 5,14 4.46 95,16 3,15 1.33
Ohafia 94,34 3.97 4.46 99.46 0,38 0.16
Ukwa 92,34 4,33 4.07 97,12 2.55 0,33
lkwuano 72.00 11.2 16,80 80,80 14,30 4,88
Mean (x) 87,31 6,3 6,8 93,1 5,09 1.67
LSD (0,05) 2.3 3,1 2,3 2,3 3,1 2,3
Source: Uwanuruochi and Nwachukwu (2012)
Three months after an artificial removal of the top (5 ern)
soil at three locations in southern Nigeria, Mbagwu et al.
(1984) observed reductions in moisture retention capacity and
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saturated hydraulic conductivities of the exposed soil layer,
which were greater in Ultisols than in Alfisols. Mbagwu and
Lal (1985) later reported that limited moisture, more than
increased compaction, caused greater reduction in root
growth and dry matter of maize (Zea mays L.) and cowpea
. (Vigna unguiculata L.) in those locations.
Apart from the usual degradation resulting from the
. opening up of land for cultivation for crop production,
land/soil resources are being exploited by various activities
without any control or check. A summary of some aspects of
the uncontrolled exploitation of land resources in Nigeria,
their description and impacts, is given in table 8.
Table 8: Environmental Impact of Uncontrolled Resource
Exploitation in Nigeria
Activity Type Exploitation
Activities General Etl'ects
I. Exploration Landscape Aesthetic deterioration of
disturbance landscape, path construction and
trampling: in wilderness.
2. Mineral Land degradation Land surface devastation
extraction and ecosystem (including erosion), land
destabilization subsidence, disruption of
drainage systems, deforestation,
excessive water drawdown, and
lowering and contamination of
the water table.
3. Processing, Gas leaks, oil spills Thermal body of waterways,
transportation, and pollution of the increase in CO2 and CO, ozone
storage and air, soil and water layer depletion, acidification of
consumption air, soil and water. weather
modifications, toxicity hazard to
plants and consumers, death of
terrestrial and marine life, loss
or crops and livestock,
impairment of atmospheric
visibility, vehicular accidents,
damage to buildings and
machinery, nervous disorder,
respiratory diseases.
cardiovascular illness. cancer
and food poisoning.
Source: NEST (1991)
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Chemical Soil Degradation
The chemistry of soil is also altered as a result of soil erosion
on farmlands. It results in net decrease in soil carbon and
nitrogen (Mainville et al. 2006) in. addition to leaching,
burning and volatilization (Roulet et al. 1999). Loss of
organic matter results in soil structural instability since it is a
major binding agent (Mikha and Rice 2004). It has been
reported that humus, which has much greater capacity to hold
water and nutrient ions compared to clay, is more easily
eroded (Esu 1999).
Soil Acidity: Soil acidity is generally regarded as one of the
major limiting factors in crop production. Soil acidity is one
manifestation of soil degradation that has physical, chemical
and biological dimensions (Eswaran et al. 1997). It results in
a complex change in the soil, such as increase in toxic levels
of aluminium and manganese, inhibition of biological
processes, reduction in the cation exchange capacity of soil,
phosphorous reserves, and diminished solubility of
molybdenum and boron. Consequently, acidic soils are in
effect also stripped of key macronutrients such as calcium,
magnesium and potassium. The decrease in root growth
coupled with the inability of plants to utilize water effectively
and take up sufficient amounts of plant nutrients is often the
most visible problem of soil acidity. All these factors
contribute to lower soil productivity, and lower crop yield.
In Nigeria, more than 70% of arable soils are acidic
especially in areas where rainfall exceeds evapotranspiration,
and there is high level of leaching of the soil nutrients. Most
of the southern states soils experience acidic conditions. In
some cases, soils are acidic due to the nature of the parent
materials which are inherently acidic especially those derived
from sedimentary and basement complex rocks.
The main reasons for low crop productivity on acid soils
are nutrient deficiency and elemental toxicity. Application of
appropriate and adequate rates of fertilizers and liming have
led to optimum yields on acid soils. Other factors that cause
soil acidity are climate (excess rainfall containing dissolved
carbon dioxide and organic acid), vegetation,. which
influences the rate of acidification, and use of acidifying
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inputs in agriculture such as ammonium containing fertilizers
which results in loss of bases from the soil and lowering of
soil pH.
Nutrient Losses: The average nutrient loss in SSA soils was
estimated to be 24kg, nutrients/ha per year (lOkg N; 4kg
P205, lOkg K20), in 1990 and 48kg nutrients/ha per year in
2000, i.e. a loss equivalent to 100kg fertilizers/ha per year
(FAO 2000). Excessive cultivation of the soil, especially in
the south-eastern states of Nigeria, leading to crop removal of
basic soil nutrients (nutrient mining) from the soil is also an
important contributing factor. Water and wind removal of
rich topsoil are, in addition, key factors that enhance nutrient
losses and soil acidity. Generally, soils in the southern states
(e.g. Lagos, Ondo, Bayelsa, Rivers, Akwa Ibom, Cross River,
Anambra, Imo) are mostly acidic due to leaching of nutrients
during the wet season with heavy rainfall. In contrast, soils in
the north-eastern states, with little or no leaching, are mostly
alkaline in nature, while those of the central states are
moderately leached and hence moderately acidic. In a
grouping of SSA countries by degree of soil nutrient
depletion (Stoorvogel and Smalling 1990), Nigeria was
placed in the 'High' (21-40 kg/yr.) group.
Sodicity and Salinity: The preponderance of sodium ions in
the soil is a common feature in the arid and semi-arid regions
and results in high soil pH (~7.5). This is known as soil
sodicity. It occurs mainly in arid and semi-arid regions and
results from accumulation of sodium salts due to inadequate
drainage. Salinity, the accumulation of salts due to capillary
rise, also poses major management problems in many
irrigated and non-irrigated areas of the semi-arid regions of
northern Nigeria. Most of the soils show both features; hence
they are saline-sodic soils. In semi-arid and arid areas of
Nigeria, the scarcity, high variation and unreliability of
rainfall and high evapotranspiration affect water and salt
balance in the soil. Oftentimes, these salts accumulate in the
topsoil and reduce the uptake of basic plant nutrients and
water through osmosis.
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These phenomena are experienced in major irrigation
schemes. About 20% of the lands, mostly in semi-arid
northern Guinea. and Sudan savanna have been degraded as a
result of salt accumulation in the soil (FAO/NPFS 2009). The
states affected by various levels of salinity are Yobe, Bornu,
Sokoto, Gombe, Kano, Kastina, Bauch, Kebei, Jigawa and
Adamawa. Crop production in these areas is highly limited by
high pH, high exchangeable sodium percentage (ESP), poor
water infiltration and inadequate 'distribution of plant roots,
because of strong prismatic structure especially in vertisols.
Some sites have been abandoned.
Soil Pollution: The major soil pollution in Nigeria is the
crude oil pollution in the oil producing areas and along the oil
pipelines.The negative effects of crude oil on the growth and
performance of plants have been reported in many researches.
These effects have been due to the interference of the plant
uptake of nutrients by crude oil and the unfavourable soil
physical and biological conditions (Gudin and Syratt 1975;
McGill and Rowell 1977). It has been reported that plants and
soil microbes compete for the little nutrient available in soils
when soil is polluted with crude oil thereby suppressing the
growth of plants in such soils.
In a United Nation Environment Programme report
(UNEP 2011) on environmental assessment in Ogoni land,
southeastern Nigeria, released in 2011, drinking water, air
and agricultural soil in 10 communities contain over 900
times the permissible levels of hydrocarbon and heavy metals
resulting from crude oil spills. The report acknowledged that
recovery after extensive compliance with recommendations
may take 30 years. A cursory look at published research work
shows that heavy metal pollution is a continental trend in
SSA (UNEP 2007). The heavy metals detected include: Pb,
Cd, Hg, Cu, Co, Zn, Cr, Ni and As (Fakayode and Onianwa
2002; Odai et al. 2008).
Loss of Soil Biodiversity: Intense management practices that
include application of pesticides and frequent cultivation,
affect soil organisms, often altering community composition
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of soil fauna. Soil biological and physical properties (e.g.,
temperature, pH, and water-holding characteristics) and
microhabitat are altered when natural habitat is converted to
agricultural production (Crossley et al. 1992). Changes in
these soil properties may be reflected in the distribution and
diversity of soil meso-fauna. Organisms adapted to, high
levels of physical disturbance become dominant within
agricultural communities, thereby reducing richness and
diversity of soil fauna (Paoletti et al. 1993). The principal
threats to soil biodiversity in SSA include land use and land
cover change, mainly through conversion of natural
ecosystems, particularly forests and grasslands, to agricultural
land and urban areas. It is likely that land clearing and
deforestation will continue, hence threatening genetic
diversity as species losses occur (IAASTD 2009).
Reduction in biological diversity of soil macrofauna is
one of the most profound ecological consequences of modern
agriculture, for example, the number of earthworm species is
largely decreased in agricultural soils. The biodiversity of the
soil organisms lead to the control (natural biological
suppression) of plant root diseases. The management
practices used in many agro-ecosysterns (e.g. monocultures,
extensive use of tillage, chemical inputs) degrade the fragile
web of community interactions between pests and their
natural enemies and lead to increased pest and disease
problems. Decline in soil biodiversity is expected to affect
soil turnover, decrease natural soil aggregation, increase
crusting, reduce infiltration rates, and thus exacerbate soil
erosion. The major factors of loss of soil biodiversity in
Nigerian soils are tillage, inorganic fertilizer application ar d
oil pollution.
In a Press Release by the International Resource Panel of
UNEP after its meeting in Beijing on June 17, 2016 (The
Guardian, June 20, 2016), the Panel stated:
Erosion, nutrient depletion, acidification, saliniza- ,
tion, compaction and chemical pollution have left
33 percent of the world's soils either moderately
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or highly degraded. If current conditions
continue, then 320-849 million hectares of land
will be converted to cropland by 2050 at the
expense of the world's savannahs, grasslands and
forests. As a result, greenhouse gas emissions
from agriculture may increase from 24 per cent to'
30 per cent, As the global population expands,
climate change 'intensifies and more people move
to urban areas, it will become increasingly
difficult to sustainably produce enough food, fuel
and fibre to meet demand without further
depleting the world's finite land resources.
It concluded that the world needs to improve the way land is
evaluated in order to unlock its true potential and reverse the
alarming pace of land degradation, like the loss of 24 billion
tonnes of fertile soil and 15 billion trees every year.
Summary of Challenges of Soil Resources Management in
Nigeria
The information provided so far shows that efforts to manage
the Nigerian soil resources are confronted by a number of
challenges which include:
• High and ever increasing population growth and
pressure;
• Increased demand for food;
• Stiff competition for land space from non-
discriminatory, non-agricultural uses;
• Dependency of livelihoods, industry and even the
service sector on agriculture, with 65-70% of the
population depending directly on rainfed agriculture
r and natural resources;
• High sensitivity of agriculture to variability and
change in climate, and markets/prices;
• Multiple severe impacts resulting from climate change
including higher temperatures, water scarcity,
unpredictable precipitation, higher rainfall intensities
and environmental stresses;
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• Fragile natural resources and ecosystems including
dry lands, mountains, rainforests, and wetlands;
• High rates of land degradation (erosion and declining
soil fertility, increasing water scarcity and loss of
biodiversity); ,
• Low yields and high post -harvest losses due to poor
land management and storage practices and limited
availability of, andaccess to, inputs.
Food Security
Crop production on fragile and highly degraded soils results
in poor yield and consequently food insufficiency. The World
Food Summit (WFS) of 1996 defined food security as
existing "when all people at all times have access to
sufficient, safe, nutritious food to maintain a healthy and
active life" (FAO 1996). The Food and Agriculture
Organization of the United Nations defines food security as
"a situation that exists when all people, at all times, have
physical, social and economic access to sufficient, safe and
nutritious food that meets their dietary needs and food
preferences for an active and healthy life" (FAO 2002).
Commonly, the concept of food security is defined as
including both physical and economic access to food that
meets people's dietary needs as well as their food
preferences. In many countries, health problems related to
dietary access are an ever increasing threat. In fact,
malnutrition and foodbome diarrhoea have become double
burden.
Of the 39 countries worldwide that faced food
emergencies at the beginning of 2003, 25 are found in Africa
(Ojo and Adebayo 2012). Several factors were listed to be
responsible for the low performance of African countries on
the issue of food security. Apart from the very high rate of
population expansion, all the others are soil or soil-related,
particularly soil degradation/soil management.
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Pillars of Food Security: From its definition, food security is
built on three pillars:
• Food availability: sufficient quantities of food
available on a consistent basis.
• Food access: having sufficient resources to obtain
appropriate foods for a nutritious diet. '
• Food quality/use: appropriate use based on knowledge
of basic nutrition and care, as well as adequate water
and sanitation.
Availability of Food is faced with challenges and risks. A
major challenge is land degradation while two major risks
are: (i) population growth and (ii) land use change. Thus,
food availability is still a concern in some agriculture-based
countries. Nigeria is one of the many countries that have
declining domestic production per capita of food staples. The
other countries are Burundi, Ethiopia, Kenya, Madagascar,
Sudan, Tanzania, and Zambia; all had negative per capita
annual growth rates in staple food of -l.0 to -l.7 percent
from 1995 to 2004 (FAO 2014). In addition, staple food
production in many agriculture-based countries is largely
rain-fed and experiences large fluctuations caused by climatic
variability.
Food access - This simply means having enough to eat. But
for most of the malnourished, the lack of access to food is a
greater problem than food availability. There is a difference
between not having enough food to eat, and there being not
enough food to eat. The irony is that most of the food
insecure live in rural areas where food is produced, yet they
are net food buyers rather than sellers. Poverty constrains
their access to food in the marketplace. According to the UN
Hunger Task Force, about half of the hungry are
smallholders; a fifth are landless; and a tenth are agro-
pastoralists, fisherfolk, and forest users; the remaining fifth
live in urban areas (FAO 2014).
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Food quality - Food use translates food security into
nutrition security. Malnutrition has significant economic
consequences, leading to estimated individual productivity
losses equivalent to 10 percent of lifetime earnings, and gross
domestic product (ODP) losses of 2 to 3 per cent in the worst-
affected countries. But malnutrition is not· merely a
consequence of limited access to calories. Food must not only
be available and accessible, but must: also be of the right
quality and diversity (in terms of energy and micronutrients),
be safely prepared, and be consumed by a healthy body, as
disease hinders the body's ability to turn food consumption
into adequate nutrition
Food Security in Developing Countries
At the very centre of concern about development must be a
concern about food, agriculture, and people. Combining these
three elements into an objecti ve that is fundamental to all else
in development is the concept of sustainable food security.
The challenge of food security is immense. The following
statistics give the idea of the situation in the developing
countries:
• An estimated 13 to 18 million people, mostly children,
die from hunger, malnutrition, and poverty-related
causes each year. That is about 40,000 people a day or
1,700 people an hour (UNDP 1993). The actual
estimate is 12.6 million children per year.
• One billion people-20 percent of the global
population-live in households too poor to obtain the
food necessary for sustaining normal life. Half a
billion live in households too poor to obtain the food
needed for healthy growth of children and minimal
activity of adults.
• One child in three is underweight by age five and
more people are undernourished now than in 1950.
• 600 million people are seriously deficient in such
micronutrients as iron and iodine, which can lead to
long-term impairment or death.
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• Most (85 to 90 percent) hunger arises from silent
poverty, and only 10 to 15 percent stems from famine
and similar emergencies: .
• Moreover, the United Nations. projects that the
number of people in "absolute poverty" will increase
by 300 million to l.5 billion by 2025 unless urgent
and positive action is taken ..
Food Security in Nigeria
An old saying in Yoruba says that if hunger can be removed
from poverty, poverty has ended. Among the developmental
problems facing Nigeria, food insecurity ranks among the
topmost (Babatunde et al. 2007). In Nigeria, the percentage of
food insecure households was reported to be 18% in 1986 and
over 40% in 2005 (Sanusi et al. 2006). Although figures
released by the FAG in 2005 on the state of food insecurity in
the world indicated that 9% of the Nigerian population was
chronically undernourished between 2000 and 2002 (FAG
2005), this was less than the regional average of 33% for Sub-
Saharan Africa.
Nigeria faces huge food security challenges. About 70
percent of the population live on less than ~HOO per day,
suffering hunger and poverty. Despite a seven percent growth
rate in agricultural production (2006-2008), Nigeria's food
import bill has risen. The growing population is dependent on
imported food staples, including rice, wheat and fish. In the
40s and early 50s, Nigeria did not have to contend with the
problem of food insecurity. The system was able to feed her
citizens and at the same time export the surplus food items.
Every region of the country specialized in the production of
one or two major crops, whether food or cash crops, and
together the country was relatively self-sufficient in food
production. Nigeria had the groundnut pyramids in the North,
cocoa in the West, oil palm and kernel heaps in the East and
rubber plantations in the Mid-West (Tell, August 3, 2009).
As mentioned earlier, when oil was discovered in 1956
and its exportation started in 1958, things started changing
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gradually, and later rapidly. As oil prices went up, interest in
agriculture waned, which marked the beginning of decline in
agricultural activities, including food production, resulting in
the rising cost of food items, especially the rise in the prices
of staple foods. In particular, the price of rice has increased
by over 100 percent since 2006. Nigeria requires 2.5 million
metric tonnes of rice annually while local lice production is
less than half a minion metric tonnes per year (Tell, May 5,
2008). Thus. Nigeria is short of two million tonnes of rice
annually, which it has to source from other countries.
In 2006, Nigeria spent $2.85 billion on the importation of
various food items. A breakdown of this figure showed that
Nigeria imported 36 percent of its rice need costing $267
million, sugar, 99 percent costing $1 billion, wheat 99, percent
totalling $1 billion and tomatoes 14 percent costing $50
million. Fish import was 66 percent per consumpticncosting
$500 million (see Newswatch, May 5, 2008)_ In 2008. it was
estimated that Nigeria spent a whopping $2 billion importing
about six million tormes of wheat, $750 million on rice, $700
million on SU1<;;i1.f. $500 million on milk and other dairy
products (Tell, May 5, 2008). In 2013, it was $4.5 billion
(table 9) and on , .ne 24, 2014, the Supervising Minister of
Niger Delta Afrs-rs (Arch. Darius Ishaku) disclosed that
Nigeria was spending N 1.3 trillion annually on importation
of food.
The President, Federal Republic of Nigeria, Muhamadu
Buhari in a speech on November 19, 2015 stated that the WI
trillion food importation bill was no longer sustainable. With
the global rise in food prices, the United Nations Food
Securitv Information Note, (FOSlN 2007) showed that
market tensions manifest, in part, through price increases and
would be most acutely felt by vulnerable households. where
difficulties in accessing cereals would lead to localized food
security problems.
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Table 9: Nigeria Top Ten commodities Import value 2011
SINo Commodity Value [1000 USD]
1 Wheat 1,475,304
2 Palm oil 1000,000
3 Sugar Raw Centrifugal 470,000
4 Milk Whole Dried 359,807
5 Flour, Malt Extract 301,368
6 Food Prep Nes 259,536
7 Sugar Refined 235,,628
8 Paste of Tomatoes 162,279
9 Milk Skimmed Dry 126,109
10 Wine 86,064
11 Total 4,476,095
Food Security Land Availability and Soil Quality
Apart from the three pillars of food security (i.e. Availability,
Access and Quality), other factors that have been identified to
influence Food Security are: Population Explosion and Water
Resources, Land/Soil Resources and Climate Change
(Premanandh 2011; Babatunde et al. 2007; Stocking 2003).
Out of 14 billion hectares of land on the planet, only 3 billion
ha is arable and this area continues to dwindle. Rapid
population growth has been suggested as the major cause of
reduced land area. For instance, there were about 12 acres per
person worldwide in 1959, and it reduced to about 6 acres per
person in 2006. A further reduction to as low as 2.8 acres per
person is estimated by 2040. Between 1960 and 2000 the
ratio of arable land to population declined by up to 55% in the
developing nations (FAO 2008; Smith et a1. 2010). Moreover,
unless soil management significantly improves, half of the
current arable land will become unusable by the year 2050
(UNCCD 2008).
Globally, around 2-5 million hectares of arable land is
estimated to be lost annually through degradation, in
particular desertification and soil erosion. The rate of
degradation is two to six times higher in Asia, Africa and
Latin America than in Europe and North America. Land
degradation in all its forms is a threat to food production and
rural livelihoods, especially in the poorest areas of the
developing world. Land demand for non-agricultural use,
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particularly urban use, has been increasing sharply in recent
times, resulting in further reduction of land availability for
food production (Kampman et al. 2008).
Soil quality is the capacity of a specific kind of soil to
function, within natural or managed ecosystem boundaries, to
sustain plant and animal productivity, maintain or enhance
water and air quality, and support human health and
habitation (Karlen et al. 1997; Doran and Zeiss 2000; Karlen
et al. 2001). Soil quality is more than the sustained capability
of a soil to accept, store, and recycle water, nutrients, and
energy. It is the capacity of soil to sustain ecological
productivity, maintain environmental quality, and promote
plant and animal health. Ecological productivity minimizes
both non-renewable inputs and polluting outputs, while
ensuring optimal production over the long term. Farmers face
an important challenge in their attempts to maintain soil
quality and productivity. This is not an easy or straight-
forward task, particularly when faced with an uncertain
climate, sloping topography, shallow soils, and/or narrow
economic margins, as is frequently the case in Nigeria. In
order to achieve genuine progress in agriculture, society as a
whole must ensure that soil quality is maintained and
improved according to a set of proposed indicators. Soil
quality should be tracked over time to achieve optimal long-
term ecological productivity.
Erosion is an important factor adversely affecting soil
quality and sustainability of cropping and farming systems. It
is more serious in the tropics than in temperate climates
because of the prevalence of fragile soils of high erodibility,
harsh climates of high erosivity, and predominately resource-
poor farmers who cannot afford to adopt conservation-
effective measures. Erosion affects crop yields and agronomic
productivity both directly and indirectly. Directly, it reduces
the effective rooting depth and available water and nutrient
retention capacities. Indirectly, it decreases use efficiency of
inputs and increases the amount of fertilizers, water and
energy needed to produce the same yield (Lal 2009).
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Depletion of soil nutrients-just one indicator of
declining soil quality-is a major cause of low per capita
food production, especially in Africa. Over the past four
decades, annual nutrient depletion rates for sub-Saharan
Africa have amounted to a fertilizer equivalent value of US$4
billion (Dreschel 1999): However, ascribing a decline in food
production unambiguously to the effects of changing soil
quality is difficult because of the complex interactions
involved, Yields decline for many reasons, such as deficiency
or excessive uptake of nutrients in crops without replenish-
ment, pests and diseases, weed infestations, and increasing
prevalence of climate change-induced drought (Stocking
2003).
There is an emerging understanding of the importance of
microbial communities for soil health through the use of
DNA and RNA methods to determine physical and chemical
changes in soil (Girvan et al. 2003). Many soil factors are
involved, including soil depth and rooting, available water
capacity, soil organic carbon, soil bio-diversity, salinity and
sodicity, aluminum toxicity, and general acidification, The
Soil Quality Institute has suggested .several indicators that
relate to yields, from which indexing approaches to measure
soil quality have been devised (Andrews 2001). One of the
main factors that integrate the effects of others is reduction in
soil organic carbon (Lal 2009). But these indicators do not
offer a comprehensive measure of the spatial and temporal
variability of soils. This lack has led to calls for inter-
disciplinary studies to understand how soil properties and
processes interact within ecosystems (Karlen et al. 2003);
how economic utility is affected (Boardman et al. 2003); and
how society, culture, and local knowledge are influenced
(Prain et al. 1999),
In general, application of fertilizers and soil amendments
masks the adverse impacts of accelerated soil erosion, In
Nigeria, Salako et al. (2007) reported 65-75% reduction in
crop yield with the removal of 25cm of topsoil when no
fertilizers or manure were applied. However, productivity of
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eroded soils was restored more effectively by the application
of manure than by use of chemical fertilizers. Similar
experiments by Oyedele and Aina (2006), also conducted on
Alfisols in Western Nigeria, indicated that grain yield of
maize (Zea mays) decreased from 3.2 Mg/ha under control to
0.1 Mg/ha where 20 cm of topsoil was removed. Maize yield
decreased exponentially with decrease in the depth/thickness
of the remai.f..~ topsoil. Drastic reduction in' maize "grain
yield on eroded soil was attributed to the low physical and
chemical quality of the exposed sub-soil. Field experiments
conducted in the West African Sahel indicated that the grain
yields of pearl millet IPennisetum glaucum) were severely
reduced on eroded and unmulched compared with uneroded
and mulched soils (Michels and Bielders 2006).
It is therefore important to make these inputs available to
minimize the adverse impacts of weather and soil
degradation, and advance food security. There is no reliable
substitute for the judicious use of inputs. Improved
germplasm cannot extract water and nutrients from
degraded/depleted soils. Therefore, making water and
nutrients available at the critical time and in appropriate
forms is essential to obtaining high yields. Growing improved
varieties can help, but these are not substitutes for the
essential inputs. Thus the challenge lies in: (i) understanding
soil processes, (ii) characterizing and mapping soil resources,
and (iii) predicting soil behaviour under a variety of land uses
and management scenarios (Miller and Mail 1995). The
strategy is to make economic-agricultural development
congruent with ecological, social and political realities, use
and conserve indigenous genetic resources, and restore
degraded soils and ecosystems (Miller and Mail 1995).
Using the ecological footprint, Kitzes et al. (2007) and
Hazell and Wood (2007) proposed two scenarios to balance
human demands and ecosystem supply: (i) managing the
consumption of food, fiber and energy, and (ii) maintaining
and increasing the productivity of agricultural ecosystems. It
is important to understand the linkages between human needs,
agriculture and the environment. The strategy is to develop
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agricultural systems which balance the pOSIt!ves and
negatives of farming to protect the production capacity and
wellbeing of the land/soil resources (Pollock et at. 2007).
There- are several technological options relevant to achieving
these goals including agro-biodiversity (Thrupp 2000),_
conservation agriculture (Hobbs et al. - 2007), and social/
political factors which determine farmers' interest in adopting
recommended practices (Shriar 2007). Recommended
practices should be those that enhance eco-efficiency or the
sustainable use of resources in farm production and land
management (Wilkins 2007).
Soil Management and Sustainable Development
What is Sustainable Development?
Sustainable development (SD) simply refers to the existence
of environmental, economic and social well-being for today
and tomorrow. More than one hundred definitions of
sustainable development exist, but the most widely used one
is from the World Commission on Environment and
Development, presented in 1987. The concept of sustainable
development is most closely associated with the 1987 report
of the United Nations World Comrriission on Environment
and Development, better known as the Brundtland
Commission, after its chairperson, Gro Harlem Brundtland of
Norway (World Commission on Environment and
Development 1987). The report popularized a compelling
definition of sustainability: "Development that meets the
needs of the present without compromising the ability of
future generations to meet their own needs".
Sustainable development promotes the idea that social,
environmental, and economic progress are all attainable
within the limits of our earth's natural resources. Sustainable
development approaches everything in the world as being
connected through space, time and quality of life. Thus, the
concept of sustainability has since been widely applied to
many aspects of human society, including wide application in
soil science and land management. The concept of sustainable
land/soil management is firmly entrenched in policy tools,
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and is central to Pillar 1 of the recently formed Global Soil
Partnership (GSP) i.e. "Promote sustainable management of
soil resources for soil protection, conservation, and
sustainable production".
Agricultural Sustainability
Agricultural Sustainable Development concept is derived
from the Sustainable Development Goals (SDGs), an offshoot :
of the Millennium Development Goals (MDGs), put together
in 2000 and signed by 189 countries including Nigeria
(MDG-Nigeria 2010). By the end of 2015, MDG was
replaced with SDG with 17 goals each with its targets and
indicators.
In March 2015, an international expert workshop
convened by the European Environment Agency (EEA) and
the Institute for Advanced Sustainability Studies (lASS) to
develop a set of indicators to contribute to the Global Land
Indicators Initiative (GLlI) and the post-2015 Development
Agenda, proposed a "shortlist" of three land and soil
management indicators. The indicators aim to support the
achievement of multiple Sustainable Development Goals
(SDGs).
The workshop's outcome document, titled 'Proposal for
Land and Soil Indicators to Monitor the Achievement of the
SDGs,' identifies three "tiered" global indicators-land
cover/land use change, land productivity change and soil
organic carbon change-all of which can be further enriched
at the national and sub-national levels. The proposal asserts
that land and soil resources underpin key services, such as the
production of food, feed, fibre and fuel, the sequestration of
carbon, nutrient cycling, protection of biodiversity, and water
regulation. It supports targets on land and soil quality and
land degradation neutrality, as proposed by the Open
Working Group (OWG) on the SDGs. It also highlights the
links between good governance of land and soil resources,
and the proposed SDG on peaceful and inclusive societies.
Noting the workshop built on on-going efforts by the UN
Convention to Combat Desertification (UNCCD) Secretariat
to explore common land indicators across the Rio
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Conventions, the experts' document describes their three
shortlisted indicators as "measurable and essential . in
capturing a minimum of land characteristics that are globally
comparable," and calls for their inclusion in the list of
proposed SDG indicators being developed by the UN
Statistical Commission (UNSC).
Sustainable development is made of three components: (i)
economic development, (ii) social development and (iii)
environmental. development. The aspect of Sustainable
Development in which the land is key is the environmental-
ecosystem services and preservation, and food security. This
involves the combination of sustainable soil/land manage-
ment, sustainable agriculture and sustainable resource
management.
From this perspective, the goal of achieving sustainable
food security in the decades ahead emerges as one of the
greatest challenges humanity has ever faced (Sanchez and
Swaminathan 2005). Agricultural output must be tripled, and
people must have the income to buy it. The erosion of the
resource base must be halted and reversed. Failure on any of
these fronts will result in unpleasant national and
international consequences. Sustain-able food security must
be seen as a fundamental aspect of global human security.
The world needs to recognize the right to food as a universal
human right. This goes well beyond the mere endorsement of
this right in principle, beyond the ringing denunciations of the
use of food as a weapon, beyond the emerging idea that
civilians in zones of armed conflict are entitled to food for
survival, and beyond humanitarian food supply measures to
prevent famine. It requires continuous practical action at all
levels-international and national, household and
individual-on the basic social responsibility to ensure that
everyone is adequately fed under all circumstances. It
requires the adoption of concrete international goals such as
reducing world hunger by half over the corning decade (Speth
1993).
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Farmers' Soil Management Strategies
Soil management is the sum total of all tillage operations,
cropping practices and treatments conducted on or applied to
a given kind of soil for the production of crops (Landon
1991). It is an integral part of land management and may
focus on differences in soil types and soil characteristics to
define specific interventions that are aimed to enhance
the soil quality for the land use selected. Specific soil'
management practices are needed to protect and conserve
the soil resources. .
The distinct climatic difference between the northern and
southern parts of Nigeria necessitates different requirements
for soil/land management to sustain crop production in the
two regions. In the moist and humid south, population
explosion and the resulting urbanization has made the old
traditional shifting cultivationlbush fallow system unsustain-
able. It has been virtually replaced by 'modem' systems
including: use of short-fallow crops (e.g. Sesbania sesban,
use of leguminous cover crops, pigeon pea), farm yard
manure (FYM), compost, animal manure (poultry, cow
dung), municipal waste, sewage sludge, organic and organo-
mineral fertilizers, etc. In the south-east, due to the sandy
nature of the soils and associated characteristics, there is
additional emphasis on conservation practices. These include:
'the traditional stone wall terracing', normal terracing, use of
earth bunds, stone pitching, Vetiver grass technology, cross
ties/tie ridges. In the drier northern part, mixed farming is the
practice with the livestock providing manure while they feed
on crop residues (in addition to normal grazing). Soil
management practices include: the traditional kraaling
(occupation of field by livestock for manuring some months
before cropping season), use of composted manure and
termatarium in planting holes, use of municipal wastes,
entrapped harmattan dust, and shelterbelt/wind break
plantation. Considerable yield increases have been obtained.
Thus, some of the soil management practices in Nigeria
hold promise. However, they cannot be applied on a large-
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scale basis because they are based on trial-and-error approach
rather than scientific data, and they cannot handle the
overwhelming soil degradation problem at hand. Besides,
increases in productivity that have been witnessed are not
commensurate with increasing demands on land resources,
and for the most part, the imminent impacts expected as a
result of climate change have yet to be taken into account
(Ogunkunle 2015b). All concerned stakeholders at different
levels as well as development partners seem to agree that
there is need for a soil management approach that is
simultaneously integrative, synergistic and encompassing;
capable of ensuring and sustaining food security for the ever-
increasing population (Ogunkunle 2015a; The (Nigerian)
Guardian 2016).
Sustainable Land/Soil Management
Sustainable Land Management (SLM) has been defined as the
adoption of land use systems that, through appropriate
management practices, enable land users to maximize the
economic and social benefits from the land while maintaining
or enhancing the ecological support functions of the land
resources (IFAD 2009; TerrAfrica 2006). In the 21st century,
food and fiber production systems will need to meet three
major requirements:
(1) Adequately supply safe, nutritious, and sufficient
food for the world's growing population.
(2) Significantly reduce rural poverty by sustaining the
farming-derived component of rural household
incomes.
(3) Reduce and reverse the degradation of natural
resources and the ecosystem services essential to
sustaining healthy societies and land productivity.
SLM requires balancing the needs for human purposes
with those for environmental conservation and functioning. It
includes management of soil, water, vegetation and animal
resources. SLM is a knowledge-based procedure that helps
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integrate land, water, biodiversity, and environmental
- management (including input and output externalities) to
meet rising food and fiber demands while sustaining
ecosystem services and livelihoods. SLM is necessary to meet
the requirements of a growing populatio,n. Improper land
management leads. to land degradation and a significant
reduction in the productive and service functions (World
Bank 2006). It involves processes and' actions to stop and/or
reverse degradation--or at least to mitigate the adverse
effects of earlier misuse. Such actions are increasingly
important in uplands and watersheds--especially those where
pressures from the resident populations are severe and where
the destructive consequences of upland degradation are being
felt in far more densely populated areas downstream. SLM
can take various forms such as:
• Preserving and enhancing the productive capabilities
of cropland, forestland, and grazing land (such as
upland areas, down-slope areas, flatlands, and
bottomlands) ;
• Sustaining productive forest areas and potentially
commercial and non-commercial forest reserves;
• Maintaining the integrity of watersheds for water
supply and hydropower-generation needs and water
conservation zones;
• Maintaining the ability of aquifers to serve the needs
of farm and other productive activities.
The ultimate aim of SLM is Agroecosystem Sustainability
which results from a nested relationship/interaction among
soil quality functions, environmental characteristics, agro-
nomic sustainability and socio-economic viability of the land
use (fig. 6).
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AGROECOSYSTE\I SUSTAI~ABI[JTY
Environmental Aeronomic Socio-Economic
Quality Su;tainabilitv Viability
E:\\'lRONMENTAL QUALITY
Soil Water Air
Quality Quality Quality
~. t ~
SOIL Qt:ALITY FUNCTIONS
Nutrient Support
Cycling Plant Growth
Fig. 6: Nested relationship among agroecosystem sustainability, soil
quality and soil functions (After Rakesh et al. 2012).
Human activities now appropriate nearly one-third to one-
half of global ecosystem production, and as development and
population pressures continue to mount, so could the
pressures on the biosphere. As a result, the scientific com-
munity is increasingly concerned about the condition of
global ecosystems and ecosystem services. Thus, land use
presents a dilemma. On one hand, many land-use practices
are absolutely essential for humanity because they provide
critical natural resources and ecosystem services, such as
food, fiber, shelter, and freshwater. On the other hand, some
forms of land use are degrading the ecosystems and services
on which we depend. So, the challenge is how to reduce the
negative environmental impacts of land use while
maintaining economic and social benefits (lFAD 2013).
Dimensions of SLM
SLM also includes ecological, economic and socio-cultural
dimensions (Hurni 1997). These three are functionally
related-they are interconnected in the process of sustainable
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food production (fig. 7). They are also referred to as the '3
Es' of sustainable management-Equality, Economy, and
Ecology (UNESCO 2006).
Ecologically, SLM technologies, in all their diversity,
effectively combat land degradation. This becomes very
crucial, since majority of agricultural land is not sufficiently
protected. . --
Socially, SLM helps secure sustainable livelihoods by
maintaining or increasing soil productivity, thus improving
food security and reducing poverty, both at household and
national levels.
Economically, SLM pays back investments made by land
users, communities or governments. Agricultural production
is safeguarded and enhanced for small-scale subsistence and
large-scale commercial farmers alike, as well as for livestock
keepers. Furthermore, the considerable offsite benefits from
SLM can often be an economic justification in themselves.
Economic
Fig. 7: The three dimensions of sustainability (After IAASTD 2009).
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Principles of Sustainable Land Management (SLM)
The primary target of SLM is to increase land productivity,
improve food security and also provide for other goods and
services. There are three ways to achieve this: (l) expansion,
(2) intensification, and (3) diversification of land use.
Expansion: Since 1960, agricultural production in Sub-
Saharan Africa has been increased mainly by expanding the
area of land under farming (Lal 2009; Blum 2013). Limited
access and affordability of fertilizers and other inputs (e.g.
improved planting material) have forced African farmers to
cultivate less fertile soils on marginal lands; these in turn are
generally more susceptible to degradation and have poor
potential for production. There is very limited scope for
further expansion without highly detrimental impacts on
natural resources (e.g. deforestation).
Intensification: Globally, the last 50 years have witnessed
major successes in agriculture, and food production largely as
a result of the 'Green Revolution' 'which was based on
improved crop varieties, synthetic fertilizers, pesticides,
irrigation, and mechanization (The Montpellier Panel 2013).
However, this has not been the case for SSA countries.
Diversification: This implies an enrichment of the production
system related to species and varieties, land use types, and
management practices. It jr'£ludes an adjustment in farm
enterprises in order to increase farm income or reduce income
variability. This is achieved by exploiting new market
opportunities and existing market niches, diversifying not
only production, but also on-farm processing and other farm-
based, income-generating activities (Dixon et al. 2001). It
involves diversified farming systems such as crop-livestock
integration, agroforestry, intercropping, crop rotation, etc.,
assisting farmers to broaden the base of agriculture, reduce
the risk of production failure, attain a better balanced diet, use
labour more efficiently, procure cash for purchasing farm
inputs, and add value to produce.
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Soil Quality as an Indicator of Sustainable Management
Developing sustainable agricultural management systems is
complicated by the need to consider their utility to humans,
their efficiency of resource use, and their ability to maintain a
balance with the environment that is favourable both to
humans and most other species (Harwood 1990). More
simply stated by Tom Franzen, a mid-western farmer in the
USA, who says: "Sustainable agriculture sustains the people
and preserves the land". We are challenged to develop
management systems that balance the needs and priorities for
production of food and fiber with those for a safe and clean
environment. Assessment of soil quality or health is
invaluable in determining the sustainability of land
management systems (Karlen et al. 1997).
Soil quality is conceptualized as the major linkage
between the strategies of conservation management practices
and achievement of the major goals of sustainable agriculture
(Acton and Gregorich 1995; Parr et al. 1992). In short, the
assessment of soil quality or health, and direction of change
with time, is the primary indicator of sustainable land
management (fig. 8). Scientists make a significant contri-
bution to sustainable land management by translating
scientific knowledge and information on soil function into
practical tools and approaches by which land managers can
assess the sustainability of their management practices
(Bouma 1997; Dumanski et al. 1991).
Specifically, assessment of soil quality/health is needed to
identify problem production areas, make realistic estimates of
food production, monitor changes in sustainability and
environmental quality as related to agricultural management,
and to assist government agencies in formulating and
evaluating sustainable agricultural land-use policies
(Granatstein and Bezdicek 1992). Use of one given approach
for assessing or indexing soil quality is fraught with
complexity and precludes its practical or meaningful use by
land managers or policy makers (Harris et al. 1996).
However, the use of simple indicators of soil quality and
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health which have meaning to farmers and other land
managers will likely be the most fruitful means of linking
science with I practice in assessing the sustainability of
management practices (Romig et al. 1995, 1996).
...- Highly Sustainable . ,
---
?: .... ..- ---
--
iii
:::l ...-
0 I Sustainable I
0
tI) I Unsustainable
l
To II
baseline Time
Fig. 8: Effect of soil quality sustainability of land use with time
(After Karlen et al. 2003 - modified)
Pillars of SLM
Recognizing that a clear objective is essential to successful
evaluation, the Framework for the Evaluation of Sustainable
Land Management (FESLM) Working Party, in Nairobi in
1991, laid a foundation for the following definition of SLM:
Sustainable land management combines techno-
logies, policies and activities aimed at integrating
socio-economic principles with environmental
concerns so as to simultaneously:
• maintain or enhance production/services
(Productivity),
• reduce the level of production risk
(Security),
• protect the potential of natural resources
and prevent degradation of soil and water
quality (Protection),
• be economically viable (Viability),
• and be socially acceptable (Acceptability).
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These five objectives of Productivity; Security; Protection;
Viability and Acceptability are seen to be the basic 'pillars'
on which the SLM edifice must be constructed and against
which its findings must be tested and monitored (Smyth and
. Dumanski 1993).
Each pillar is complex, and requires further : brief
examination:
Productivity: The returns from SLM may extend beyond
material yields from agricultural and non-agricultural uses to
include benefits from protective and aesthetic aims of land
use.
Security: Management methods that promote balance
between a land use and prevailing environmental conditions
reduce the risks of production; conversely, methods that
destabilize local relationships increase that risk.
Protection: The quantity and quality of soil and water
resources must be safeguarded, in equity for future
generations. Locally, there may be additional conservation
priorities such as the need to maintain genetic diversity or
preserve individual plant or animal species.
Viability: If the land uses being considered are not locally
viable, the use will not survive.
Acceptability: Land use systems can be expected to fail, in
time, if their social impact is unacceptable. The populations
most directly affected by social and economic impact are not
necessarily the same.
Strategies for Sustainability
In defining sustainable agricultural management practices,
Doran et al. (1994) stressed the importance of holistic
management approaches that optimize the multiple functions
of soil, conserve soil resources, and support strategies for
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promoting soil quality and health. They initially proposed use
of a basic set of indicators to assess soil quality and health in
various agricultural management systems. Experience has
shown thatwhile many of these key indicators are extremely
useful to specialists (i.e. researchers, consultants, extension
staff, and conservationists), many of them are beyond the
expertise of the producer to measure (Hamblin 1991), Also,
the measurement of soil quality and health does nothing to
improve the sustainability of the system under which the soil
is managed. In response to this dilemma, Doran et al. (1996)
and Doran and Safley (1997) presented strategies for ensuring
sustainable management which included generic indicators of
soil quality and health which are measurable by and
accessible to producers within the time constraints imposed
by their normally hectic and unpredictable schedules, as
given in table 10.
It is noteworthy that soil organic matter serves as a
primary indicator of soil quality and health for both scientists
and farmers (Romig et al. 1995). Strategies for sustainable
management, such as those shown in table 10, maximize the
benefits of natural cycles, reduce dependence on non-
renewable resources, and help producers identify long-term
goals for sustainability that also meet short-term needs for
production. However, successful development and imple-
mentation of standards for assessment of soil health and
sustainability can only be accomplished in partnership with
agricultural producers, who are the primary stewards of the
land.
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Table 9: Sustainability Strategies and Proposed Indicators of Crop
Performance and Soil Health
Sustainability Stratezv Indicators for Land Users/Producers
Conserve soil organic matter by Change in organic matter levels
maintaining soil C & N levels through color (visualj.or chemical
through reduction in tillage, recycling analysis; specific OM potential for
plant and animal manures and/or climate, soil and vegetation, soil water
increasing plant diversity where C storage
inputs> C outputs
Minimize soil erosion through Visual (gullies, rills, dust etc-); Surface
conservation tillage and increased soil properties (topsoil depth, organic
protecti ve cover (residue stable matter content/ texture, water
aggregates, cover crops, green infiltration, runoff,
fallow) ponding, % cover)
Balanced production & environment Crop characteristics (visual or remote
through conservation and integrated sensing of yield, colour, nutrient status,
management systems (optimizing plant vigour and rooting
tillage, residue, water and chemical characteristics); Soil physical
use) and by synchronizing available conditions/compaction Soil and water
N and P levels with crop needs nitrate levels Amount and toxicity of
pesticides used
Better use of renewable resources Input/output ratios of costs and energy
through relying less on fossyl fuels Leaching losses/soil acidification Crop
and petrochemicals and more on characteristics (as listed above) Soil
renewable resources and biodiversity and water nitrate levels
(crop rotation, legumes. manures
lPM etc.)
Source: Doran et al. (1996)
Some Established Systems of SLM
About 46% of Nigeria's vast cultivable land area (71.2
million ha) is currently in agricultural use (NLUP 2012).
Expanding this area to boost the food supply for ensuring
food security is not an acceptable option, rather the emerging
paradigm of sustainable intensification (The Montpellier
Panel 2013), is more desirable and can be adopted for
building resilience in Nigerian agriculture. The old practice of
bush burning in the dry season still persists with the resultant
soil nutrient depletion due to the destruction of the organic
matter in the soil surface and addition to the problem of
climate change. Indiscriminate soil excavation to obtain sand
and/or gravel for building or road construction is another
major practice that affects the Nigerian soil resources
adversely. The major soil management systems considered
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sustainable are: Integrated Soil Fertility Management (ISFM),
Conservation Agriculture (CA) and Organic Agriculture
(OA). Precision Agriculture (PA), the application of
Computer Technology to enhance efficiency and economic
performance, can be integrated with any of these systems.
Integrated Soil Fertility Management (ISFM)
Integrated Soil Fertility Management (ISFM) has been
defined as a set of soil fertility management practices that
necessarily include the use of fertilizer, organic inputs and
improved germplasm combined with the knowledge on how
to adapt these practices to local conditions, aiming at
optimizing agronomic use efficiency of the applied nutrients
and improving crop productivity (Vanlauwe et al. 2015;
Fairhurst 2012). All inputs need to be managed following
sound agronomic and economic principles.
This definition combines all the agronomic components
necessary to make crops grow and yield well, including the
use of high yielding and healthy planting material, plant
nutrients, whether supplied as organic materials or mineral
fertilizers, and other soil amendments. The ISFM approach
embraces the principles of plant production ecology where
yield is a function of the interaction between genotype,
environment and management:
Yield = G (genotype) + E (environment) + M
(management),
Where:
• Genotype is the seed or plants used in the farming
system, local or improved varieties.
• Environment refers to the soils and climate in the
particular location.
• Management refers to the farmer's ability and skill in
managing crops and the farming system.
A model can be used to illustrate the impact of moving
towards more complete implementation of ISFM. However, it
has been established that:
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(1) The more complete the implementation of ISFM,
with all the necessary inputslinterventions (fig. 6),
the greater the value for agronomic efficiency.
(2) It shows the distinction between responsive soils and
less responsive soils-the response to seed and
fertilizer and other inputs is large in responsive soils,
but small in non-responsive 'degraded' soils.
(3) Organic resources are required to make efficient use
of fertilizer and improved seeds.
(4) Full implementation of ISFM requires knowledge on
how to adapt practices to each farm's peculiarities
(Fairhurst 2012).
ISFM involves the combined use of appropriate int...ventions
on soil management, fertilizer use and crop agronerny to
drive the main outputs of increased yield and productivity.
The introduction of interventions is affected by market
economics and government policy. When introduced success-
fully, productivity is increased and less land is required to
achieve a given level of production. The impact is the
sustainable improvement of food security, increased farm
incomes and lower food prices, which benefit the urban
population (fig. 9).
'-- __ Int_enoen_t_._..,. ~> ~
RoI.ll;G!\;'it'!le!'<;rop ct'lOl..;'e
$0",,'I.ge J ""re'"","mccmes
Soi!corJ$.efvJ:ixm--¥- E 1
ronJ'l),"Jrd manure use --- ; ~
; Q
crco r~U1ti"..;managemel':-l _._... i'
F:e:ft);iire::=5;O~~:~e~_:~ , "e=::==; I.
Ii
C,QO JJ;~fr ti'x..'lCe ···_··--·····1 ~ /
Pta ru 'i"=l ---}
Watet' r;J.f'~,ont Z~
Lewes
W~e.<j~age~efl: E
Deeose ~!,j;)emtfll -- - " =/ foodcrees
P:'>sI<T'IIlr...'\IJ<tt'~t _ _ __._ _ .• L_~
Fig. 9: ISFM as an integral process for SLM and food security. Source:
Fairhurst (2012)
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Conservation Agriculture (CA)
CA is an approach to managing agro-ecosystems for
improved and sustained productivity, increased profits and
food security while preserving and enhancing the resource
base and the environment (FAG 2015).
The predominant form of agricuiture is based on the
'interventionist approach', in which most aspects of the
production system are controlled by human technological
interventions, such a'S soil tilling, curative pest and weed
control with agrochemicals, and the application of synthetic
mineral fertilizers for plant nutrition. Most of these crop
production systems are both economically and environ-
mentally vulnerable and unsustainable (MEA 2005; WDR
2008; McIntyre et al. 2008; Foresight 2011). However, there
are now a growing number of production systems with the
'ecosystem approach', underpinned by healthy soils, and
designated as Conservation Agriculture (CA), that are not
only effective in producing food and other raw materials
economically, but also more sustainable in terms of land
management and environmental services and impacts. Their
further development and spread merit deeper support with the
development of suitable policies, funding, research, techno-
logies, knowledge diffusion, and institutional arrangements.
Principles of CA in relation to Sustainability
The production systems which follow a predominantly
ecosystem approach offer a range of productivity, socio-
economic and environmental benefits to producers and to
society at large on a sustainable basis. They are based on five
overall objectives:
(i) Simultaneous achievement of increased agricultural
productivity and enhanced ecosystem services;
(ii) Enhanced input-use efficiency, including water,
nutrients, pesticides, energy, land and labour;
(iii) Judicious use of external inputs derived from fossil
fuels (such as mineral fertilizers and pesticides) and
preference for alternatives (such as recycled organic
matter, biological nitrogen fixation and integrated
pest management);
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(iv) Protection of soil, water and biodiversity through use
of 'minimum soil disturbance' and maintaining
organic matter cover on the soil surface to protect the
soil and enhance soil organic matter and soil
biodiversity; and
(v) Use of managed and natural biodiversity of species to
build systems' resilience to abiotic, biotic and
economic stresses, with an underlying emphasis on
improving soils' content of organic matter as a
substrate essential for the activity of the soil biota.
The farming practices required to implement these objectives
will differ according to local conditions and needs, but will
have the following necessary characteristics:
(i) Minimum soil disturbance by mechanical tillage -
Physical soil problems such as compaction are
rectified and, as much as possible, seeding or
planting is directly into untilled soil in order to
maintain soil organic matter, soil structure and
overall soil health;
(ii) Maintenance of organic matter cover on the soil
surface, using crops, cover crops or crop residues.
This protects the soil surface, conserves water and
nutrients, promotes soil biological activity and
contributes to integrated weed and pest management;
and
(iii) Diversification of species - both annuals and
perennials-in associations, sequences and rotations
that can include trees, shrubs, pastures and crops, all
contributing to enhanced crop nutrition and improved
system resilience.
The practices described above are those generally associated
with CA, now widely used in all continents-c-over 117
million hectares (Kassam et al. 2010). However, for
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production intensification, these CA practices should be
strengthened by the following additional best management
practices:
(i) Use of well adapted, high yielding varieties and good
quality seeds;
(ii) Enhanced crop nutrition, based on healthy soils;
(iii) Integrated management of pests, diseases and weeds;
and
(iv) efficient water management.
Sustainable crop production intensification is the combination
of all seven of these improved practices applied in a timely
and efficient manner. Such sustainable production systems
are knowledge and management intensive and relatively
complex to learn and implement. They offer farmers many
possible combinations of practices to choose from and adapt,
according to their local production conditions and constraints
(Pretty 2008; Kassam et al. 2009; FAO 2010, 2011; Pretty et
al. 2011).
Uniqueness of CA for Sustainable Land Management
Sustainable agricultural land management and production
intensification is facilitated with CA because biological
optimization of soil conditions is continuous, and repeated
soil-recuperative breaks (essential in tillage-based systems)
are unnecessary. A main criterion for ecologically sustainable
production systems or sustainable land management is the
maintenance of an environment in the root-zone to optimize
soil biota, including healthy root functions, to the maximum
possible depth. Roots are thus able to function effectively and
without restrictions to capture plant nutrients and water as
well as interact with a range of soil microorganisms
beneficial for soil health and crop performance (Shaxson
2006; Uphoff et al. 2006; Shaxson et al. 2008; Kassam et al.
2009). Maintenance or improvement of soil organic matter
content and biotic activity, soil structure, and associated
porosity, are critical indicators for sustainable production and
other ecosystem services.
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A key factor for maintaining soil structure and organic
matter is to limit mechanical soil disturbance in the process of
crop management. This is because it provokes accelerated
oxidation of organic matter and loss of the resulting CO back
into the atmosphere. In so doing, it depletes soil organic
matter, the energy-rich substrate for the life processes of the
soil biota which are essential for developing and maintaining
any soil in a healthy and productive condition. Nevertheless,
for any agricultural system to be sustainable in the long term,
the rate of soil formation-from the surface downwards-
must exceed the rate of any degradation due to loss of
organic matter (living and/or non-living), and of soil porosity,
evidenced by consequent soil erosion. In the majority of
agroecosystems, this is not possible if the soil is mechanically
disturbed (Montgomery 2007). For this reason the avoidance
of unwarranted mechanical soil disturbance is a starting point
for sustainable production. Not tilling the soil is therefore a
necessary condition for sustainability, but not a sufficient
condition: other complementary techniques including mulch
cover, crop rotations and legume crops are also required.
The sustainable crop production principles of CA
described above can be readily integrated into other
ecosystem-based approaches to generate greater benefits. For
example, System for Rice Intensification (SRI) has proven to
be successful as a basis for sustainable intensification in all
continents under a wide range of circumstances. Trained
farmers have shown that SRI embodies CA principles to offer
higher factor productivities and income, and requires less
seeds, water, energy, fertilizer and labour compared with
conventional irrigated or rainfed flooded rice production
systems (Kassam et al. 2011).
Organic Agriculture (Farming)
Organic agriculture is defined by International Federation of
Organic Movements (IFOAM) as, "a production system that
sustains the health of soils, ecosystems and people. It relies
on ecological processes, biodiversity and cycles adapted to
local conditions, rather than the use of inputs with adverse
effects. Organic agriculture combines tradition, innovation
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and science to benefit the shared environment and promote
fair relationships and good quality of life for all involved"
(IFOAM 1998).
One of the primary objectives of organic agriculture is to
increase the sustainability of agricultural systems. Organic
agriculture uses a whole system approach based upon a set of
processes resulting in sustainable ecosystems, safe food, good
nutrition, animal welfare and social justice. It is more than
just a system' of production that includes or excludes certain
inputs, particularly agro-chemicals, because it builds on and
enhances the ecological management skills of farmers, fisher
folk and pastoralists. Practising organic or agro-ecological
agriculture requires ecological knowledge, planning and
commitment to work with natural systems, rather than trying
to change them. Industrial agriculture uses an opposite
approach; it provides inputs and technologies to substitute
and thus reduces or destroys the inherent diversity of natural
systems (Sombrock et al. 2003). It contributes to both land
degradation and climate change. This is vividly portrayed in
the books The Fatal Harvest: The Tragedy of Industrial
Agriculture and The Fatal Harvest Reader: The Tragedy of
Industrial Agriculture (Kimbrell 2002).
In 2004, IFOAM published a scoping study on "The Role
of Organic Agriculture in Mitigating Climate Change"
(Kotschi and Muller-Samann 2004). The study looked at how
organic agriculture could contribute to reducing greenhouse
gas (GHG) emissions and mitigate the impacts of climate
change, Specifically, organic agriculture;
• encourages and enhances biological cycles within the
farming system;
• Maintains and increases long-term fertility in soils;
• Uses, as far as possible, locally available renewable
resources in locally organized production systems;
and
• Minimizes all forms of pollution (IFOAM 1998),
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Organic Agriculture's Contribution to Carbon
Sequestration
The emphasis on strengthening the internal nutrient and
energy cycles inherent in organic agriculture offers a means
to sequester carbon dioxide in the soil and in the vegetation.
Kotschi and Muller-Samarin (2004) reported the results of a
study that compared carbon sequestration by organic and
conventional agricultural systems. Organic agriculture
showed a clear advantage with an efficiency of 41.5%
compared to 21.3% for conventional farming. The study also
showed the much higher contribution to sequestration of root
biomass as compared with above ground biomass.
The relationship between organic agriculture, traditional
agriculture and sustainable agriculture is illustrated in figure
10. Organic agriculture is often equated with the use of
organic fertilization techniques, systematic application of
manure and compost from animal and crop residues, crop-
legume rotations, green manuring with legumes, and
agroforestry with multipurpose leguminous trees. Much
expertise has been developed in these techniques and the use
of these practices has produced outstanding improvements in
productivity and environmental health, as the case study from
Tigray, northern Ethiopia, demonstrates. In Switzerland, a
long-term comparison between organic and conventional
agricultural systems was carried out. After 18 years, soi Is
treated with organic manures were found to contain 3-8 t ha
more carbon than those that had had chemical fertilizer
treatment (Kotschi and Muller-Sarnann 2004).
In 2003, IFOAM commissioned a study to provide an
overview of the status of the organic movement in Africa
(IFOAM 2003). The survey covered both the formal
(certified) and non-formal sectors for 22 of Africa's 54
countries. This represented 40% of the land area of the
continent. Certified organic agriculture covers both large
commercial and small-holder farmers. In global terms, only
1% of land under certified organic agriculture is found in
Africa, but, because most of the farms are small (1-3 ha) the
continent accounts for almost 10% of the farmers growing
certified organic crops worldwide. The principles behind
organic agriculture are also used in programmes and projects
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focused on overcoming food insecurity, rural poverty and
environmental degradation. In 2003, IFOAM reported that
over 40,000 farms covering 235,000 ha of land were growing
certified organic products in Africa (IFOAM 2003).
Fig. 7: Conceptual relationship between traditional agriculture, organic
agriculture, certified organic agriculture and sustainable agriculture in
the context of all agriculture.
Source: Twarog 2006, in UNCTAD Trade and Environment Review 2006: 144
Organic Agriculture in Nigeria
Organic Agriculture in Nigeria is very young, within the last
two decades, although use of manure or decomposed organic
materials from dump sites is an age-old practice. The practice
of modem organic farming is at a relatively low level in
Nigeria compared with developed countries. It is mainly at
the research and awareness stage, production is very low and
limited to the universities, research institutes and a few
farmers. The awareness is concentrated in the south,
particularly, South-West (table 11). It is being coordinated by
the Nigerian Organic Agriculture Network (NOAN). Land
area under Organic Agriculture in Nigeria was 3,134 ha in
2007 and 11,979 ha in 2010 (Global Agric. Information
Network 2014).
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Table 10: Awareness of Organic Agriculture in Nigeria
Geo-Political Region % Awareness
North - East 1.35
North - West 2.7
North - Central 4.95
South - East 2.19
South - West 76.57
South.- South 12.16
Source: Glo~al Agric. Inform. Network 2014
Biochar Technology
There is a growing interest in using biochar (charco: Ior black
C) as a soil amendment and for sequestering C and L »proving
soil quality. It has been acclaimed as a sustainable way to
improve soils and decrease the use of chemical fertilizers
(Lima et al. 2002). Biochar is a solid material obtained from
the thermochemical conversion of biomass in an oxygen-
limited environment-which creates a fine-grained, highly
porous charcoal (Renwick et al. 2002; Rumpel et al. 2006).
Application of biochar to soil can improve soil fertility.
Application of biochar can enhance soil quality in many
ways, including: (i) increase in soil's cation exchange
capacity; (ii) decrease in loss of nutrients; (iii) increase in
soil's microbial activity; (iv) improvement of soil structure
and water retention capacity; and (v) increase in buffering
against soil acidification (Fowles, 2007). In addition, biochar
can also be used for remediation and/or protection against
particular environmental pollution and as an avenue for
greenhouse gas (GHG) mitigation (Marris 2006). This is thus
an area of great potential in OA for food security and climate
sustainability CIPCC2007; Stem 2007).
Precision Agriculture
Precision agriculture (PA) (satellite farming or site specific
crop management (SSCM), is a farming management concept
based on observing, measuring and responding to inter and
intra-field variability in crops. Precision agriculture is one of
many modem farming practices that make production more
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efficient. With precision agriculture, farmers and soils work
better, not harder. The term first came into popular use with
the introduction of GPS (global positioning satellites) and
GNSS (global navigation satellite systems) as well as other
methods of remote sensing which allowed farm operators to
create precision maps of their fields that provide detailed
. information on their exact location while in-field, thus
making possible accurate prediction of soil conditions and/or
crop performance at any location in the farm. Advancements
in technology have enabled the practice of precision
agriculture to expand, providing even greater advantages for
farmers and agricultural operations, including yield
monitoring and crop scouting. With precision agriculture,
control centers collect and process data in real time to help
farmers make the best decisions with regard to planting,
fertilizing and harvesting crops. Sensors placed throughout
the fields are used to measure temperature and humidity of
the soil and surrounding air.
There are several aspects of precision agriculture that can
be applied to various types of farming operations, but they all
share a common feature-the use of technology to enhance
economic performance, better use of inputs and help to
mitigate environmental damage.
Recent Development: "The Green Alternative"
Just at the completion of the preparation of this lecture,
specifically on Wednesday, zo" of July, 2016, the Federal
Executive Council approved the Agricultural Policy of the
Government tagged 'The Green Alternative' for implement-
ation. The Minister of Agriculture in his presentation called it
the "Road map for agricultural operation for the next three
years," outlining the policy and objectives to make
agriculture "the next and biggest alternative" to oil in the
nation's drive to diversify the economy of this country. The
Minister went further: "We are fully aware that there is a
major concern in the country for food self-sufficiency and
that there is crisis in many families as a result of serious
shortage of food." The policy reveals Government's plan for
"a huge investment in soil mapping/testing" One can only
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pray and hope that 'The Green Alternative' has truly
recognized the key role of soil resources management in the
successful programme on food security and sustainable
development.
Conclusion
The importance of soil resources in agricultural (food)
production has been trivialized in Nigeria over the years.
Thus, serious attention is not given to soil problems. In spite
of the high degree, of soil loss and depletion of soil quality
through degradation in the country, little effort is made to
redress it. There is no authentic national soil classification
and map based on accurate soil data. Apart from inorganic
fertilizer application and the old shifting cultivation/bush
fallow system, all other management systems being adopted
by farmers were acquired by trial-and-error. Consequently,
yields of most of Nigerian arable crops are very low
compared with their potentials. Food security, an indicator of
sustainable development, cannot be achieved under such a
system.
In addition, inherent characteristics of the Nigerian soil
resources show that the soils are of marginal to average
quality and the same is true of their capacity for supporting
arable crops. For the quality and capacity of the soils to be
improved and/or sustained, soil degradation must be
minimized. This requires adequate knowledge of the
characteristics of the soils so that the appropriate combina-
tions of soil management and land use can be adopted. The
fragile nature of the soils makes them highly susceptible to
soil degradation of various types, water erosion being the
most devastating. Several factors are responsible for the
degradation, but the ones that stand out are deforestation,
overgrazing and excavation/quarrying, excessive cultivation,
and oil pollution in the oil-producing regions. Climate change
has introduced further complications to exacerbate the effects
of these factors. In addition, the relatively high rate of
population expansion and the resultant demand for more food
has forced the expansion of areas under cultivation to
marginal lands, thus leading to more degradation.
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This lecture therefore, has attempted to create a special
awareness that the major problem militating against food
security in Nigeria is the poor quality, highly degraded and
poorly managed soil resources. It has emphasized the need for
more information on the characteristics of the soils,
avoidance of activities that lead to soil degradation, and
encouragement of practices that enhance organic matter
conservation in the top soil. Thus, the lecture calls for the
adoption of appropriate sustainable management and
conservation of the nation's agricultural soil resources to
achieve food security for sustainable development in the
country.
Sustainable land/soil management (SLM), a system that
preserves the land and sustains the people seems to be the
way out. From its dimensions, characteristics (Pillars) and
strategies, SLM has the capacity to preserve the land
resources to meet human needs and development. It is a
knowledge-based procedure that integrates land, water,
biodiversity, and environmental management in order to meet
rising food demands while sustaining ecosystem services and
livelihoods. SLM is necessary to meet the requirements of a
growing population. The soil management strategies
presently in use by Nigerian farmers cannot sustain soil
quality and capacity for food security or self-sufficiency in
food production for the Nigerian population.
Soils must not be taken for granted in any meaningful
agricultural policy. While adoption of improved crop varieties
is important, agronomic production can neither be improved
nor sustained unless soil quality is restored and maintained.
Maintaining soil quality and water resources at optimal levels
is essential for realizing the potential of improved varieties.
Degraded soils do not respond to other inputs unless their
physical, chemical and biological quality is restored.
The adoption of a number of science-based SLM systems
that have been developed which have been adjudged to be
effective for sustaining agricultural land use is very crucial to
our success in food production. They are: Integrated Soil
Fertility Management (ISFM), Organic Agriculture (OA), and
Conservation Agriculture (CA). A detailed analysis of these
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systems shows that each of them is specialized in terms of
approach, emphasis and area of impact (e.g. ISFM for
chemical soil fertility, CA for conservation against soil
loss/erosion). Therefore, a combination of any two or even
the three of these systems (or some aspects of each) may be
required for optimum sustainable management of the soil
resources. Relevant type(s) of Precision Agriculture (PA) can
be combined with any of the options selected to take
advantage of modern technological advancement for greater
and faster accomplishment.
Obviously, food security cannot be attained with the
present attitude towards an essential resource as the soil.
There is urgent need for agricultural transformation in which
soil resources will be given their rightful place so that food
security and hence, sustainable development will be a reality
even with the ever increasing population in Nigeria. It is
hoped that the current fall in oil price in the world market will
force Nigeria to get its priorities right by wisely investing in
agricultural production and research. If this can be done, the
present suffering from the low price of oil will turn out to be
a blessing in disguise.
Recommendations
On the premise of this lecture, I wish to make the following
recommendations:
• Soil Resource Inventory: There is urgent need for
characterization, classification and mapping of the soil
resources in the country, with mapping at semi-
detailed scale at the national level and detailed scale at
the State level. This will enhance accurate prediction
of the most appropriate land use and management for
any area of interest in the country.
• Resuscitation of Federal Department of Agricultural
Land Resources (FDALR) with adequate funding and
review of its mandate to meet the demands of
sustainable agriculture, food security, and minimal
land degradation.
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• Establishment of a functional National Soil Inform-
ation System (NISIS) to produce a data bank (of the
major soils, their characteristics and appropriate land
use and management) which can be made available to
farmers and land users on request in all the Geo-
political regions in the country.
• Benchmark Soils Programme for continuous research
on Sustainable Soil Management for the Major Kinds
of Soils in, the country, evaluation of sustainable
management systems for their performance on the
benchmark soils, and necessary adjustments/
modifications before they are recommended to
farmers.
• Establishment of a National Institute of Soil Science
for the overall monitoring and supervision of
activities/practices on soil resources in the country
and standardization of the practice of soil science.
(This has been pushed by the Soil Science Society of
Nigeria, has been passed by the Senate, and is
awaiting endorsement ,by the House of
Representati ves.)
• Legislation (and enforcement) against all forms of soil
abuse e.g. bush burning, indiscriminate soil excava-
tion, overgrazing, indiscriminate deforestation, etc.
• A review of the Federal Government's Department or
Unit in charge of Sustainable Development Goals
(SDGs) and its activities to establish professional sub-
committees for relevance and performance.
Alternatively, SDG committees can be formed based
on grouping of similar goals in terms of professions
(e.g. agriculture and environment, etc.).
Acknowledgement
I give all thanks, praises and glory to God Almighty my
Father, to Jesus, my Lord and Saviour and the Holy Spirit, my
guide and enabler-for sustenance, favour and grace to make
this humble but crucial contribution towards the progress of
my nation, Nigeria.
I wish to thank all my teachers from the elementary
school to the University for their investments in my life. In
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particular, I wish to remember Late Professor P.H.T. Beckett
who supervised my D.Phii. project.
Ivery much appreciate my Colleagues and other members
of staff of the Department of Agronomy, where I have spent
over three decades of my life. I have enjoyed a very friendly
atmosphere in my interactions with both staff and students. I
pray that this progress and unity will increase and continue to
produce ground-breaking research in Jesus' name. My Head
of'Department, Professor Victor Adetimirin and my Dean,
Professor E.A.' Iyayi who nominated me and the Vice-
Chancellor and the Management of the University who
approved my nomination for this Lecture, I appreciate you
very much. My current Head of Department, Professor E.A.
Akinrinde and Dean, Professor B.O. Omitoyin, I appreciate
you both for your support. Dr. Julius Orimoloye, Professors
Akin Oluwatosin and Gabriel Akinbola assisted me in the
preparation of this lecture. I very much appreciate all of you.
Several people have played one role or the other to get me to
the stage of being qualified to give the 2016 University
Lecture, I thank you all and pray that you will continue to
enjoy the favour of God in Jesus' name.
I wish to appreciate members of my family, my children,
Oluwanbe, Ife and his wife Kemi and children; my late
parents, my siblings, uncles, aunties and in-laws; my Church
(Pastor, Deacons and other members); thank you for your
love, support, and prayers, May you never miss the love and
support of the Lord in Jesus' name. Lastly, my darling wife,
Dr. Oluwatoyin Ogunkunle, you have been wonderful. I very
much appreciate your care, love, patience and encouragement
through thick and thin, hence I dedicate this Lecture to you.
Let us listen to the counsel of the Wise in the Holy
Scriptures: "And further, by these, my son, be admonished: of
making many books there is no end; and much study is a
weariness of the flesh". Let us hear the conclusion of the
matter: "Fear God and keep His Commandments: for this is
the whole duty of man".
To God be the Glory, Honour and Adoration. Amen.
Thank you for your attention.
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References
Abate, T., van Huis A. and J.K.O. Ampofo 2000. Pest management
strategies in traditional agriculture: An African perspective.
Annu. Rev. Entomol. 45: 631-659.
Abegunde Albert A., Samson A. Adeyinka, Peter O. Olawuni and
Olufunmilayo A. Oluodo. 2006. An Assessment of the Socio
Economic Impacts of Soil Erosion in South-Eastern Nigeria TS
56 - Special Valuation Situations. Shaping the Change, XXIII
FIG Congress, Munich, Germany, October 8-13,2006.
Acton, D.F. and L.J. Gregorich. (eds.). 1995. The health of our
soils - towards sustainable agriculture in Canada Centre for
Land and Biological Resources Research, Research Branch,
Agriculture and Agri-Food Canada, Ottawa, Ont. xiv + 138 pp.
Adeniran, J.R. 1993. The Study of Flood Hazards in Nigeria: An
Unpublished Seminar Paper, Department of Geography,
University of lIorin.
Agbu, P.A. and A.G. Ojanuga. 1989. Properties and classification
of soils of Dange area of Sokoto State, Nigeria. Samaru
Journal of Agricultural Research 6: 37-47.
Ahmad, N. and A. Mermut (Eds.). 1996. Vertisols and technologies
for their management. Developments in Soil Science 24. New
York: Springer-Verlag. 548pp .
Ahn, P.M. 1970. West African soils. Third Edition, Oxford
University Press.
Andrews, S.S. and C.R Carroll 2001. Ecol. Appl. 11, 1573-1585.
Aribisala, T.S.B. 1983. Nigeria's Green Revolution: Achievements,
Problems and Prospects. Distinguished Lecture No.1, NISER,
Ibadan, April 1983.
Babalola, O. and R Lal. 1977. Subsoil gravel horizon and maize
root growth I and II. Plant and Soil, 46: 337-357.
Babalola, O. 2007. Soil erosion problems in Nigeria: The use of
Vetiver System Technology. Being the Report of the Research
carried out as the Occupant of the First Bank of Nigeria
Professorial Chair in the Faculty of Agriculture and Forestry,
University of Ibadan between 2002 and 2005. Ibadan
University Press, 91pp.
Babatunde, RO., O.A. Omotesho and O.S. Sholotan. 2007. Factors
influencing food security status of rural farming households in
North Central Nigeria. Agricultural Journal 2(3): 351-357.
75
UNIVERSITY OF IBADAN LIBRARY
Beinroth, P.H .. Hari Eswaran and P.P. Reich. 2001. Global
Assessment of Land Quality. Selected Paper from 10th
International Soil Conservation Organization Meeting. May 24-
29, 1999, at Purdue University, pp. 569-574
Blum, Winfried E.H. 2013. Soil and land resources for agricultural
production: General trends and future scenarios - A worldwide
perspective. International Soil and Water Conservation
Research 1(3): 1-14.
Boardman, J., J. Poesen and R. Evans .. 2003. Socio-economic
factors in soil erosion and conservation. Environ. Sci. Policy 6,
1-6.
Borlaug, N. 2007. Feeding a hungry world. Science 318-3:"9.
Bouma, 1. 1997. Soil environmental quality: A European
perspective. J. Environ. Qual. 26: 26-31.
Charman, P.E.V. and B.W. Murphy (eds.). 2005. Soils .. Their
properties and management. Oxford University Press in
association with NSW Department of Land and Water
Conservation, Melbourne, Vic., 237-245.
Chokor, B.A. and F.O. Odemerho. 1994. Land degradation
assessment by small-scale traditional African farmers and
implications for sustainable conservation management.
Geoforum 25: 145-154.
Crossley, D.A., Jr., B.R. Mueller, and J.e. Perdue. 1992.
Biodiversity of micro-arthropods in agricultural soils: Relations
to processes. Agric. Ecosyst. Environ. 40: 37-46.
Crosson, P. 1995. Soil erosion and its on-farm productivity
consequences: What do we know? Washington, DC:
(Resources for the Future).
Dakora, P.D. and S.O. Keya. 1997. Contribution of legume
nitrogen fixation to sustainable agriculture in Sub-Saharan
Africa. Soil BioI. Biochem. 29, 5-6; 809-817.
Dixon, John and Aidan Gulliver with David Gibbon (Principal
Editor: Malcolm Hall). 2001. Farming Systems and Poverty:
Improving Farmers' Livelihoods in a Changing World. Rome
and Washington D.e.: FAO and World Bank.
Doran, 1.W., D.e. Coleman, D.P. Bezdicek and B.A. Stewart.
1994. Defining Soil Quality for a Sustainable Environment.
Soil Science Society of America Special Publication No. 35.
Soil Science Society of America and American Society of
Agronomy. Madison, WI.
76
UNIVERSITY OF IBADAN LIBRARY
Doran. lW. and M. Safley. 1997. "Defining and Assessing Soil
Health and Sustainable Productivity". In Biological Indicators
of Soil Health. ed. Pankhurst, C. et al. Wallingford, UK: CAB
International 1-28.
Doran, J.W., M. Sarrantonio and M. Liebig. 1996. Soil health and
sustainability. Advances in Agronomy. Vol. 56. ed. Sparks,
D.L. San Diego: Academic Press, pp. 1-54.
Doran, J.W. and M.R. Zeiss. 2000. Soil health and sustainability:
Managing the biotic component of soil quality. Applied Soil
Ecology 15: 3-11.
Douglas, M.G. 1994. Sustainable Use of Agricultural Soils: A
Review of the Prerequisites for Success or Failure.
Development and Environment Reports No. 11, Group for
Development and Environment, Institute for Geography,
University of Berne, Switzerland.
Dreschel, P. and L.A. Gyiele. 1999. The Economic Assessment of
Soil Nutrient Depletion, International Board for Soil Research
and Management, Bangkok.
Dumanski, J., H. Eswarari and M. Latham. 1991. A proposal for an
international framework for evaluating sustainable land
management. In: Evaluation for Sustainable Land Management
in the Developing World, Vol. 2,.J. Dumanski, E. Pushparajah,
M. Latham, R. Myers and Collin R. Elliot (Eds.). Technical
papers. Bangkok, Thailand: International Board for Soil
Research and Management, 1991. IBSRAM Proceedings no.
12,2, pp25-48.
Esu, I.E. 1999. Fundamentals of Pedology. Ibadan, Nigeria:
Stirling-Horden Publishers.
2005: Characterization, Classification and
Management Problems of the Major Soil Orders in Nigeria.
26th Inaugural Lecture, University of Calabar, Nigeria.
Esu, I.E. and A.G. Ojanuga. 1989. X-ray diffraction evaluation of
the silt and clay minerals in some soils in Kaduna, Nigeria.
Nigerian Journal of Scientific Research 2: 76-83.
Eswaran, R., P. Reich and F. Beinroth. 1997. "Global Distribution
of Soils with Acidity". In Plant-Soil Interactions at Low pH.
Moniz, ed. A.c. et al. Brazilian Soil Science Society. pp. 159-
164.
FADE (Fight against Desert Encroachment). 2013. Special Report
on Desertification in Nigeria ..
UNIVERSITY OF IBADAN LIBRARY
Fakayode, S.O. and P.e. Onianwa. 2002. Heavy metal
contamination of soil, and bioaccumulation in Guinea grass
(Panicum maximum) around Ikeja Industrial, In Advances in
Soil Science, ed. R. Lal and B. Stewart. New York: Springer-
Verlag. 59,499-510.
Fairhurst, T. (Ed.). 2012. Handbook for integrated soil fertility
management. Africa Soil Health Consortium, Nairobi. CAB
International. 164pp.
Farella, N., Cucotte, M., Louchouarn, P. and M. Roulet. 2001.
Deforestation modifying.
FDALR. 1990. 'The Reconnaissance Soil Survey of Nigeria
(l :650,000). Soils Report. Fed. Dept. Agric. Land Resources,
Abuja, Nigeria.
FAO. 1996. Declaration on World Food Security. World Food
Summit, Rome: FAO.
____ . 2000. The State of Food and Agriculture: Lessons
from the Past 50 Years. Rome: FAO.
____ . 2002. Land and agriculture. Challenges and
perspectives for the World Summit on Sustainable
Development, Johannesburg 2002. Rome.
____ .2004. Carbon Sequestration in Drylands Soils. World
Soil Resources Reports 102. FAO.
____ . 2005. Food and Agriculture Organization of the
United Nations (2005) Disasters 29 (Suppl. 1):sl-s4.
____ . 2006. The State of Food Security in the World, Rome
Italy: FAO.
____ .2008. Assessment of the World Food Security. Rome:
FAO.
____ . 2009. The Special Challenge for Sub-Saharan Africa:
Issues Brief. Presented at the 2009 High-Level Expert Forum
on: "How to Feed the World in 2050." Rome: FAO, October
12-13,2009.
____ .2010. FAO CA website at: www.jao.org/aglca
____ . 2011. Food and Agriculture Organization of the
United Nations.
____ . 2014. The State of Food Security in the World:
Strengthening the Enabling Environment for Food Security and
Nutrition. Rome Italy: FAO.
____ .2015. Conservation Agriculture; Rome: FAO.
FAOSTATS. 2005. FAOSTAT data 2005. (Accessed June 26,
2005).
78
UNIVERSI Y OF IBADAN LIBRARY
FOSIN. 2007. United Nations Food Security Information Note,
November, 2007.
Foresight. 2011. The future of food and farming. London: The
Government Office for Science.
Fowles, M. 2007. Black carbon sequestration as an alternative to
bioenergy. Biomass Bioenerg. 31: 426-432.
Girvan, M.S., J. Bullimore, J.N. Pretty, A.M. Osborn and A.S. Ball.
2003. Appl. Environ. Microbiol. 69, 1800.
Global Agricultural Information Network. 2014. Organic
Agriculture in Nigeria, 1-13.
Granatstein, D. and D.F. Bezdicek. 1992. The need for a soil
quality index: Local and regional perspectives. Am. J. Altern.
Agric. 7: 12-16.
Gudin, C. and W.J. Syratt. 1975. Biological aspects of land
rehabilitation following hydrocarbon contamination.
Environmental Pollution 8: 107-112.
Hamblin, A. 1991. Environmental Indicators for Sustainable
Agriculture. Report of a national workshop. Publ. LWRRDC
and GRDC, 96 pp.
Harris, R.F., D.L. Karlen and D.J. Mulla. 1996. "A Conceptual
Framework for Assessment and Management of Soil Quality
and Health. In Methods for Assessing Soil Quality ed. Doran,
J.W. and Jones, A.L., SSSA Special Publication No. 49,
American Society of Agronomy. Pages 61-82.
Hartmans, E.H. 1984. Prospects for Nigerian Agriculture. NISER
Distinguished Lecture Series, University of Ibadan.
Harwood, RR 1990. "A History of Sustainable Agriculture". In
Sustainable Agricultural Systems. ed. Edwards, C.A .. Lal. R.,
Madden, P., Miller, RH., House, G., Ankeny, Iowa, USA: Soil
and Water Conservation Society, 3-19.
Hazell. P. and S. Wood. 2007. Drivers of change in global
agriculture, Philos. T. Roy. Soc. B, DOl: 1O.10981rstb. 2007.
2166.
Hillocks, RJ., J.W.M. Logan, c.a. Riches and Smith A. Russell.
1996a. Soil pests in traditional farming systems in sub-Saharan
Africa - A review. 1. Problems. Int. J. Pest Manage 42:
241-251.
Hobbs, P.R 2007. Conservation agriculture: What is it and why is
it important for future sustainable food production? J Agric Sci
145: 127-137.
79
UNIVERSITY OF IBADAN LIBRARY
Hughes, 1. 1978. Mineralogy of Soils from Southern Nigeria in
Relation to their Classification and Utilization. Ph.D. Thesis,
University of Reading.
Humi, Hans. 1997. Concepts of sustainable land management. ITe
Journal 210-215.
IAASTD. 2009. Agriculture at a Crossroads: International
Assessment of Agricultural Knowledge, Science and
Technology for Development. Synthesis Report 106pp.
IFAD. 2009. The .Strategic Investment Program for Sustainable
Land Management in Sub-Saharan Africa, Rome: IFAD.
_____ . 2013. Smallholders, food security, and the environ-
ment. International Fund for Agricultural Development (IFAD)
54pp
IFOAM. 1998. Basic Standard for Organic Production and
Processing. IFOAM General Assembly, Argentina.
____ . 2003. Organic and Like-minded Movements in
Africa: Development Status. Compiled by Nicholas Parrot and
Bo van Elzakker ofAgro Eco, for IFOAM, IFOAM, Bonn.
IPCe. 2007. Fourth Assessment report. Impacts, Adaptation and
Vulnerability. Contribution of Working Group II to the Fourth
Assessment Report of the Intergovernmental Panel on Climate
Change, Cambridge University Press.
Izuchukwu, Oji-Okoro. 2011. Analysis of the Contribution of
Agricultural Sector on the Nigerian Economic Development.
World Review of Business Research 1: 191-200.
Jimoh, H.l. 2000. "Individual Rainfall Events and Sediment
Generation on Different Surfaces in IIorin, Nigeria", A Ph.D.
Thesis submitted to the Department of Geography, University
of Ilorin, Ilorin, 220 pp.
Jones, M.J. and A. Wild. 1975. Soils of the West African Savanna.
Tech. Commmmunication No. 55, CAB, Harpenden, England.
Jungerius, P.D. 1964. The soils of eastern Nigeria. Pub. Servo
Geologique du Luxenbourg 14: 185-198.
Juo, A.S.R. 1979. Chemical characteristics. In D.J. Greenland (Ed.)
Characterization of soils in relation to their classification and
management for crop production: Example from some areas of
the Humid Tropics. Oxford University Press, 51-79.
Kampman, B., F. Brouwer and B. Schepers. 2008. Agricultural
Land Availability and Demand in 2020. A Global Analysis of
Drivers and Demand for Feedstock and Agricultural Land
Availability CE Delft. Delft, 64pp.
80
UNIVERSITY OF IBADAN LIBRARY
Karlen, D.L., M.l Mausbach, J.W. Doran, RG. Cline, RF. Harris
and G.E. Schuman. 1997. Soil quality: A concept, definition,
and framework for evaluation. Soil Sci. Soc. Am. 1. 61: 4-10.
Karlen, D.L., S.S. Andrews and J.W. Doran. 2001. Soil quality:
Current concepts and applications. Advances in Agronomy 74:
1-40.
Karlen, D.L., S.S. Andrews, B.J. Weinhold and J.W. Doran. 2003.
Soil quality: Humankind's foundation for survival. Journal of
Soil and Water Conservation 58: 171-179.
Kassam, A.H., T. Friedrich, T.P. 'Shaxson and J.N. Pretty. 2009.
The spread of Conservation Agriculture: Justification,
sustainability and uptake. International Journal of Agriculture
Sustainabilitv 7: 292-320.
Kassam. A.H .. T. Friedrich and R Dernsch. 2010. Conservation
Agriculture in the 21st century: A paradigm of sustainable
agriculture. Proceedings of the European Congress on
Conservation Agriculture, Madrid, Spain, October 2010.
Kassam, A.H., W. Stoop arid N. Uphoff. 20ll. Review of SRI
modifications in rice crop and water management and research
issues for making further improvements in agricultural and
water productivity. Paddy and Water. Environment 9: 163-180
(DOI1O.1007/s10333-0ll-0259-1).
Kimbrell, A. (2002) The Fatal Harvest and The Fatal Harvest
Reader: The Tragedy of Industrial Agriculture. Foundation for
Deep Ecology. "
Kitzes, r, M. Wackernagel, J. Loh, A. Peller, S. Goldfinger, D.
Cheng and K. Tea. 2008. Shrink' and Share: Humanity's
present and future Ecological Footprint. Philos. T. Roy. Soc. B
363: 467-475.
Klinkenberge, K. and G.M. Higgins. 1968. An outline of northern
Nigerian soils. Nigerian Journal of Science 2: 9-115.
Kotschi, land Samann K. Muller. 2004. The role of organic
agriculture in mitigating climate change - A scoping study.
Bonn: IFOAM.
Lal, R 1986. Soil surface management in the tropics for intensive
land use and high crop production. Advances in Soil Science 5:
1-109. New York: Springer-Verlag, Inc.
_____ ,. 1990. Soil erosion and land degradation: The global
risks. Soil degradation 1.
_____ . 1998. "Basic Concepts and Global Issues: Soil
Quality and Agricultural Sustainability". In Soil Quality and
Agricultural Sustainability. ed. Lal, R. Ann Arbor Science,
Chelsea, MI, USA, 3-12.
81
UNIVERSITY OF IBADAN LIBRARY
Lal, R. 2009. Soils and food sufficiency: A review. Agronomy for
Sustainable Development, Springer VerlagfEDP Sciences/
INRA, 29(1): 113-133.
Landon, J.R (Ed.). 1991. Booker Tropical Soil Manual. A
handbook for Soil Survey and Agricultural Land Evaluation in
the Tropics.
Lima, H.N., e.E.R Schaefer, J.W.V. Mello, RJ. Gilkes and J.e.
Ker. 2002. Pedogenesis and pre-Columbian land use of "Terra
Preta Anthrosols" (Indian Black Earth) of western Amazonia,
Geoderma 110, 1-17.
Liniger, H.P., RM. Studer, e. Hauert and M. Gurtner. 2011.
Sustainable Land Management in Practice-Guidelines and Best
Practices for Sub-Saharan Africa.
Lobell, D.B., M.B. Burke, C. Tebaldi, M.D. Mastrandea, W.P.
Falcon and RL. Naylor. 2008. Prioritizing climate change
adaptation needs for food security in 2030. Science 319:
607-610.
Maineville, N., J. Webb, M. Lucotte, R. Davidson, O. Betancourt,
E. Cueva and D. Mergler. 2006. Decrease in soil fertility and
release of mercury following deforestation in the Andean
Amazon, Napo River valley, Ecyador. Sci. Total Environ. 368:
88-98.
Marris, E. 2006. Putting the carbon back: Black is the new green.
Nature 442: 624-626.
Mbagwu, J.S., ex. Lal and T.W. Scott. 1984. Effects of
desurfacing of alfisols and ultisols in southern Nigeria: I. Crop
performance. Soil Science Society of America Journal 48(4):
828-833.
Mbagwu, J.S.e. and R La\. 1985. Effect of bulk density and
irrigation frequency on root growth and dry matter yields of
com and cowpeas for three Nigerian topsoil and subsoil
profiles. Beitrage zur Tropischen Landwirtschaft und
Yeterinarmedirin 23: 277-285.
McGill, W.B. and M.J. Rowell. 1977. The reclamation of
agricultural soils after oil spills. In Soil Biochemistry. ed. Paul
EA, Ladd IN, New York, Dekker, pp 69 - 132.
McIntyre, B.D., H.R Herren, J. Wakhungu and RT. Watson (Eds).
2008. Agriculture at a Crossroads: Synthesis. Report of the
International Assessment of Agricultural Knowledge, Science,
and Technology for Development (IAASTD). Island Press,
Washington, De.
82
UNIVER
ITY OF IBADAN LIBRARY
Millenium Development Goals - Nigeria. 2010. Count Down
Strategy Report. Federal Republic of Nigeria.
MEA. 2005. "Ecosystems and Human Well-Being: Synthesis". In
Millennium Ecosystem Assessment. Washington, DC.: Island
Press.
Michels, K. and CL. Bielders. 2006. Pearl millet growth on an
erosion affected soil in the Sahel. Exp. Agr. 42: 1-17.
Miller, P.P. and M.K. Mail 1995. Soil, land use and sustainable
agriculture: A review. Can. J. Soil Sci. 75: 413-422.
Mikha, M.M. and C.W. Rice. 2004. Tillage and manure effects on
soil and aggregate-associated carbon and nitrogen. Soil Sci.
Soc. Am, J. 68: 609-816.
Montgomery, D. 2007. Dirt: The erosion of civilizations. Berkeley
and Los Angeles: University of California Press, 287 pp.
Moorman, P.R. 1981. "Representative Toposequences of Soils in
Southern Nigeria and their Pedology". In Characterization of
Soils in Relation to their Classification and Management for
Crop Production. ed. Greenland, DJ. Clarendon Press. 10-29.
NEST. 1991. Nigeria's Threatened Environment: A National
Profile. Nigeria: A NEST Publication.
Newswatch. 2008. Newswatch International Magazine, Lagos.
NLUP. 2012. National Land Use Policy. Federal Ministry of
Agriculture and Rural Development (FMARD).
Noma, S.S., 1.1. Tanko. M. Yakubu, A.U. Dikko, A.A. Abdullahi
and M. Audu. 2011. Variability in the physico-chemical
properties of the soils of Dundaye District, Sokoto State,
Nigeria. Proceedings of the 45th Annual Conference of the
Agricultural Society of Nigeria, held at the Faculty of
Agriculture, Usmanu Danfodiyo University Sokoto, Nigeria,
24th to 28thOct, 2011, ed. Hassan, W.A. et al.
Nwajiuba, Chinedum. 2010. Nigeria's Agriculture and Food
Security Challenges. Agriculture & Food Security, 45-63
NTWG. 2009. Report of the Vision Nigeria 2020. National
Technical Working Group on Agriculture & Food Security.
2009.
Nye, P. and D.G. Greenland. 1960. Soils under Shifting
Cultivation. Commonwealth Agric. Bureau, Harpenden,
England.
Odai, S.N., E. Mensah. D. Sipitey, S. Ryo and E. Awuah. 2008.
Heavy metals uptake by vegetables cultivated on urban waste
dumpsites: Case study of Kurnasi. Ghana. Res. J. Environ.
Toxicol. 2: 92-99.
83
UNIVERSITY OF IBADAN LIBRARY
Ofomata, G.E.K. 2001. Missing links in the management of soil
erosion problems in Nigeria. In Geographical Perspectives on
Environmental Problems and Management in Nigeria. eds.
G.E.K. Ofomata and P.O. Phil-Eze. Enugu: Jamo Enterprises,
258-283.
Ogunkunle, A.O. 1981. An appraisal of the capacity of Nigerian
soils I to sustain food self-sufficiency. Nigerian Agric. Journ.
29: 13-32.
_____ ,. 1986. Properties, Management and Evaluation of
Nigerian Soil Resources. Paper presented at the l" National
Seminar on Agricultural Insurance, IITA, Ibadan, Nigeria.
_____ . 1988. Soil Resource Inventory and Agricultural
Productivity in Nigeria. In Increasing Productivity in Nigeria.
National Productivity Centre, Lagos, Chapter 42: 440-448.
_____ . 1989. Topographic location, soil characteristics and
classification in three bio-geological locations in Mid-Western
Nigeria. Malay. J. Trop. Geog. 19: 22-32.
___ . 2009. Management of Nigerian Soil Resources for
Sustainable Agricultural Productivity and Food Security.
Invited paper, Proceedings of the 33rd Annual Conf. SSSN,
March 9-13 2009, Ado-Ekiti, 9-14.
_____ . 2010. Management of Nigerian Soil Resources for
Sustainable Agricultural Productivity and Food Security;
Invited Paper, Proc. 33m Ann Con! Soil Sc. Soc. Nig., Ado-
Ekiti, 9-13 March, 2009,9-24.
_____ . 2015a. Managing land for sustainable development:
Experience from sub-Saharan Africa. Proceedings of the
Annual Ibadan Sustainable Development Summit, 23-28
August. 2015.
_____ ,. 2015b. Soil quality maintenance by sustainable land
use/management: An imperative for food security. Nigerian
Journal of Soil Science, Special Edition, 11-45.
Oguukunle, A.O. and O. Babalola. 1986. Capability groupings of
some soils in the low lands of Benue River. Proc. 14th Soil Sci.
Soc. Conf., 46-58.
Ogunkunle, A.O. and M.O. Akoroda. 1992. State of Nigerian
Agriculture: Past and Present. Paper presented at the Seminar
for Nigerian LGA Agric. Officers and Administrators, 15-18
June, 1992, University of Ibadan, Nigeria.
Ojo, E.O. and P.F. Adebayo. 2012. Food Security in Nigeria: An
Overview. Eur. J. Sustain. Dev. 1(2): 199-222.
84
UNIVERSITY OF IBADAN LIBRARY
Olaniyan, J.O. and A.O. Ogunkunle. 20073. An assessment of the
accuracy oftbe soil map of Kwara State, Nigeria. Niger. J. Soil
Sc. 17: 16-23.
____ . 2007b ..An Evaluation of the Soil Map of Nigeria. II
Purity of Mapping Unit. J. World Assoc. Soil Water Conserv.,
J2,9'1-1O&.
Otdeman, L.R. 1994. "The Global Extent of Soil Degradation. In
Soil Resilience and Sustainable Land Use. ed. Greenland, DJ.,
Szabolcs, I. CAB International, Wallingford, Oxon, UK, pp ..
99-118.
Olusegun O. Awotoye, Clement O. Ogunkunle and Sunday A.
Adeniyi, 2011.' Assessment of soil quality under various land
use practices in a humid agro-ecological zone of Nigeria.
African Journal of Plant Science 5(10): 565-569, 27
September, 2011.
Otsuka. K. 2006. Why can't we transform traditional agriculture in
Sub-Saharan Africa? Rev. Agr. Econ. 28: 332-337.
Oyedele, D.J. and P.O. Aina. 2006. Response of soil properties and
maize yield to simulated erosion by artificial topsoil removal.
Plant Soil 284: 375-384. .
Paoletti, M.G., W. Foissner and D.C. Coleman. 1993. Soil Biota,
Nutrient Cycling and fanning Systems. Lewis, Boca Raton, Fl.
Parr, J.F., R.I. Papendick, S.B. Hornick and R.E. Meyer. 1992. Soil
quality: Attributes and relationship to alternative and
sustainable agriculture. Am. J. Altern. Agric. 7: 5-11.
Pollock, c., J. Pretty, I. Crute, C. Leaver and H. Dalton. 2007.
Introduction. Sustainable Agriculture, Philos. TR. Soc. B,
DOl: 1O.1098/rstb.2007.2193.
Pretty, Jules. 2008. Agricultural sustainability: Concepts, principles
and evidence, Phil. Trans. R. Soc. B 363: 447-465.
Pretty, .LN., C. Toulrnin and S. Williams. 2011. Sustainable
intensification in African agriculture. International Journal of
Agricultural Sltsrainability 9( 1): 5-24.
Prain, G., S. Fujisaka and M.D. Warren. (Eds.). 1999. Biological
and cultural diversity: The role of indigenous agricultural
experimentation in development. London: Intermediate
Technology.
Premanandh Jagadeesan. 201 L Factors affecting food security and
contribution of modem technologies in food sustainability. J
Sci Food Agric 91: 2707-2714.
85
UNIVERSITY OF IBADAN LIBRARY
Renwick, A., A.S. Ball and IN. Pretty. 2002. Agriculture has a
potentially large role in the sequestration of carbon in soils.
Phi/os. Trans.R. Soc. London Ser. A 360, 1721.
Rakesh, K.M., K.S. Rao, J. Laishram and K.G. Saxena. 2012. Soil
Quality and Soil Health: A Review. International Journal of
Ecology and Environmental Sciences 38(1): 19-37,2012.
Romig, D.E., M.J. Garlynd,RF. Harris and K. McSweeney. 1995.
How farmers assess soil health and quality. Journal of Soil
Water Conservation 50: 229-236.
Romig, D.E., M.J. Garlynd and RF. Harris. 1996. "Farmer-based
Assessment of Soil Quality: A Soil Health Scorecard. In
Methods for Assessing Soil Quality. ed. Doran, J.W., Jones,
A.J., Soil Science Society of America, Special Publication 49,
Madison, WI, pp. 39-60.
Roulet, M., M. Lucotte, N. Farella, G. Serigue, H. Coeiho and e.J.
Sousci Passos. 1999. Effects of recent human colonization of
the presence of mercury in Amazonian ecosystems. Water Air
Soil Pollut. 112: 297-313.
Rukuni, M. 2002. Africa: Addressing growing threats to food
security. J. Nutr. 132: 3443S-3448S.
Rumpel, e., M. Alexis, A. Chabbi, V. Chaplet, D.P. Rasse, e.
Valentin and A. Mariotti. 2006. Black carbon contribution to
soil organic matter composition in tropical sloping land under
slash and bum agriculture, Geoderma 130: 35-46.
Salako, F.K., P.O. Dada, c.o. Adejuyigbe, M.a. Adedire, O.
Martins, CA. Akwuebu and O.E. Williams. 2007. Soil strength
and maize yield after topsoil removal and application of
nutrient amendments on a gravelly Alfisol toposequence. Soil
Till. Res. 94: 21-35.
Sanchez, P.A. and RRB. Leakey. 1997. Land use transformation
in Africa: Three determinants for balancing food security with
natural resource utilization Eur. J. Agron. 7: 15-23.
Sanchez, P.A. and M.S. Swaminathan. 2005. Cutting world hunger
in half. Science 307: 357-359.
Sanusi, RA., e.A. Badejo and B.a. Yusuf. 2006. Measuring
household food insecurity in selected local government areas of
Lagos and Ibadan, Nigeria. Pakistan Journal of Nutrition
5: 62-67.
Sharu, M.B., M. Yakubu, S.S. Noma and A.1. Tsafe. 2013.
Characterization and classification of soils on an agricultural
landscape in Dingyadi District, Sokoto State, Nigeria. Nigerian
Journal of Basic and Applied Science 21(2): 137-147.
86
UNIVERSITY OF IBADAN LIBRARY
Shriar, A.J. 2007. In search of sustainable land use and food
security in the arid hillside regions of Central America: Putting
the horse before the cart. Hum. Ecol. 35: 275-287.
Shaxson, T.F. 2006. Re-thinking the conservation of carbon, water
and soil: A different perspective. Agronomie 26: 1-9.
Shaxson, T.F., A.H. Kassam, T. Friedrich. R. Boddey and A.
Adekunle. 2008. Underpinning conservation agriculture's
benefits: The roots of soil health and function. Integrated Crop
Management Vol. 6r2008. Appendix 1, FAO, Rome.
Singh, R.B. and G.A. Babaji. 1990. Characteristics of the soils of
Dundaye District 2. The Fadama Soils of University Farm.
Nigerian Journal of Basic and Applied Science 4: 29-39.
Smith, P., P.J. Gregory, D. van Vuuren, M. Obersteiner, P. Havlik,
M. Rounsevell, J. Woods, E. Stehfest and J. Bellarby. 2010.
Competition for land. Philosophical Transactions of the Royal
Society B, London 365, 2941-2957.
Smyth, A.J. and J. Dumanski. 1993. FESLM: An International
Framework for Evaluating Sustainable Land Management.
World Soil Resources Report, Food and Agriculture
Organization of the United Nations, 1993.
Smyth, A.J. and P.R. Montgomery. 1962. Soils and Land use in
Central Western Nigeria, Govermnent Printer, Ibadan, 265pp.
Soil Quality Institute (http://soils.usda.gov/SQI.
Sombroek, W., M. de Lourdes Ruivo, P.M. Fearenside, B. Glaser.
and J. Lehmann. 2003. Amazon dark earths as carbon stores
and sinks. In Amazon Dark Earths: Origin, Properties and
Management. ed. Lehmann J., Kern D.C., Glaser B., Woods
W.I. Kluwer Academic Pub.
Speth, J.G. 1993. Towards Sustainable Food Security by,
CONSULTATIVE GROUP ON INTERNATIONAL
AGRICULTURAL RESEARCH (CGIAR). Sir John Crawford
Memorial Lecture. International Centers Week, October 25,
1993, Washington, D.C.
Stern, N. 2007. The economics of climate change - The Stem
Review. Cambridge University Press, UK.
Stocking. M. 2003. Erosion and crop yield. Encyclopedia of Soil
Science. New York: Dekker.
Stoorvogel, J.J. and E.M.A. Smaiing. 1990. Assessment of Soil
Nutrient Depletion in sub-Saharan Africa: 1983-2000. Report
28, Wageningen, Netherlands; Winnard Staring Centre for
Integrated Land. Soil and Water Research.
87
UNIVE
SITY OF IBADAN LIBRARY
Stromgaard, P. 1991. Soil nutrient accumulation under traditional
African agriculture in the Miombo Woodland of Zambia. Trop.
Agr. 68: 7¢-80.
TerrAfrica. 2006. Assessment of the Nature and Extent of Barriers
and Bottlenecks to Scaling Sustainable Land Management
Investments throughout Sub-Saharan Africa. Unpublished
TerrAfrica report.
Tell. 2008. Tell International Magazine, Lagos.
Terrestrial organic transpOrt in the Pio Tapajos, Brazilian Amazon.
Org. Gecohem. 32: 1443-1458.
The (Nigerian) Guardian. 2016. Evaluate Land to Halt Annual Loss
of 24 Billion Tonnes of Fertile Soil, Expert Panel Says. Press
Release of Meeting of International Resource Panel of UNEP,
Beijing, 17 June, 2016.
The Montpellier Panel. 2013. Sustainable intensification: A new
paradigm for African agriculture. Agriculture for Impact:
London.
Thrupp, L.A. 2000. Linking agricultural biodiversity and food
security: the valuable role of agrobiodiversity for sustainable
agriculture. Int. Affairs 76, 265.
Twarog, S. 2006. Organic Agriculture: A Trade and Sustainable
Development Opportunity .for Developing Countries.
UNCTAD, 2006. Trade and Environment Review. UN, New
York and Geneva: United Nations.
Ukeje, R.O. 2003. Macroeconomics: An Introduction, Port
Harcourt Davidson Publication. World Review of Business
Research 1(1): 191-200, March 2011.
UN. 2015. The Millenium Development Goals Report 2015. New
York. www.un.org/milleniumgoals/2015MDGReport/pdf/MDG.
UNCCD. 2008. Desertification, land degradation, drought bring
rising hunger and agricultural bankruptcy. Press Release,
United Nations Convention to Combat Desertification, Bonn.
UNCCD Secretariat. 2013. A Stronger UNCCD for a Land-
Degradation Neutral World, Issue Brief, Bonn, Germany.
UNDP. 1993. Human development report 1993. New York: Oxford
University Press.
UNEP. 1982. World's soil policy. Nairobi, Kenya: United Nations
Environment Programme.
_____ ,. 2007. Reactive nitrogen in the environment: Too
much or too little of a good thing. Nairobi, Kenya: United
Nations Environment Programme.
88
UNIVERSITY OF IBADAN LIBRARY
UNEP. 2011. Towards a green economy: Pathways to sustainable
development and poverty eradication. United Nations
Environment Programme (UNEP), Nairobi, Kenya.
http://www. unep.org/g reeneconomy/g reeneconomyreport/tabid
/29846/default.aspx .
_____ . 2012. Avoiding Future Famines: Strengthening the
Ecological Foundation of Food Security through Sustainable
Food Systems United Nations Environment Programme
(UNEP), Nairobi, Kenya.
_____ .2013. Second Global Conference on Land - Oceans
Connection (GLOC-2) 2-4 October, 2013, Montego Bay,
Jamaica.
UNESCO. 2006. Curriculum Rationale: Understanding Sustainable
Development. http://www.unesco.org/educationltlsfITLSF/
theme,almod02/uncom02t02.htm; accessed 3 March 2010.
Uphoff, N., AS. Ball, E. Fernandes, H. Herren, O. Husson, M.
Laing, C. Palm, J. Pretty, P. Sanchez, N. Sangingaand J. Thies
(Eds.). 2006. Biological approaches to sustainable soil
systems. CRC Press, Taylor & Francis Group, Boca Raton, FL.
Uwanuruochi, AO. and 0.1. Nwachukwu. 2012. Impact of erosion
on selected soil structural indices of four Local Government
Areas of Abia State, Nigeria, Publication of Nasarawa State
University, Keffi 8(2): 127-133.
van der Westhuizen, A. 2004. Plant defence mechanisms:
Relevance to agriculture in Africa. South Afr. J. Bot. 70:
124-127.
Vanlauwe, B., A Bationo, J. Chianu, K.E. Giller, R. Merckx, U.
Mokwunye, O. Ohiokpehai, P. Pypers, R. Tabo, K.D.
Shepherd, E.M.A Smaling, P.L. Woomer and N. Sanginga.
2010. Integrated soil fertility management: Operational
definition and consequences for implementation and
dissemination. Outlook on Agriculture 39( 1): 17-2.
Vanlauwe, B., K. Descheemaeker, K.E. Giller, J. Huising, R.
Merckx, G. Nziguheba, J. Wendt and S. Zingore. 2015.
Integrated soil fertility management in sub-Saharan Africa:
Unravelling local adaptation. SOIL 1: 491-508.
Vine, P.N., R. Lal and D. Payner. 1981. The influence of sands and
gravels on root growth of maize seedlings. Soil Sc. 131:
124-129.
89
UNIVERSITY OF IBADAN LIBRARY
Wilkins, R.J. 2007. Eco-efficient approaches to land management:
A case for increased integration of crop and animal production
systems. Philos. T. Roy. Soc. B, DOl: lO.1098Irstb.2007.2167.
World Bank. 2006a. Agriculture Investment Sourcebook, 2006.
Washington, DC: World Bank. http://web.worldbank.org/
WBSlTEIEXTERNAUfOPlCSIEXTARDIEXTAGISOUIO"menu
PK:2502803-pagePK:64l68427-piPK:64168435-theSitePK:
2502781,OO.html, accessed December 2007.
_____ .2016. Food Security: Overview. World Bank Report,
Washington D.C., March, 2016.
World Commission on Environment and Development. 1987. Our
common future. New York: Oxford University Press, 46.
World Development Report. 2008. Agriculture for Development.
World Bank, Washington, DC.
Wudiri, B.B. and 1.0. Fatoba. 1992. Cereals in the food economy
of Nigeria. In Proceedings of Workshop on Recent
Developments in Cereal Production in Nigeria. ed. Lawani,
S.M. and Babaleye, T. Media Forum for Agriculture, 13-32.
Yakubu, M. 2001. Survey, Classification and Genesis of soils of
Kalambaina area, Sokoto State, Nigeria. M.Sc. Thesis,
Department of Soil Science and Agricultural Engineering,
University of Agriculture, Abeokuta (Unpublished).
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BIODATA OF
PROFESSOR AYOADE OLA YIWOLA OGUNKUNLE
Professor Ayoade Olayiwola Ogunkunle was born on the io"
of August 1947 to Mr. Amos Ogunwole and Mrs. Abigail
Faderera Ogunkunle, both of blessed memory.
He attended Ishokun Baptist Day School (1954-1960),
Oranyan Grammar School, Oyo (1962-1967); University of
Ife (1968-1972) and University of Oxford, England (1975-
79).
Professor Ogunkunle taught briefly in St. David's
Anglican Modern School, Odeomu in 1968 after his School
Certificate. He entered the University of Ife the same year to
study Agriculture. He graduated in 1972 and taught briefly in
Ila Grammar School, Ila-Orangun, He joined the Nigerian
Institute for Oil Palm Research (NIFOR) as Research Officer-
in-Training in 1973. He left NIFOR in 1975 to study for the
D.Phil. degree in Pedology and Soil Survey at Oxford
University and returned to NIFOR in 1979 after completing
his study. He was a recipient of the Western Nigeria
Government and Federal Government Scholarships for the
undergraduate and postgraduate degrees respectively.
Professor Ogunkunle joined the Department of Agronomy
as Lecturer Grade I in April 1983. He was promoted Senior
Lecturer in 1988, Reader in 1993 andProfessor in 1996.
He was the Departmental Coordinator of Consultancy,
Departmental Coordinator of PG and Undergraduate
Seminars, and Member of Ile-Ogbo land Acquisition
Committee.
Professor Ogunkunle has conducted researches on soil
survey techniques.. soil variability and land use/cropping
pattern, quantitative and conventional techniques of land
evaluation, application of numerical classification to soil
correlation, quality control in soil survey, soil quality and
land use.
He has published 117 academic articles, single or co-
authored, made up of 2 chapters in books, 90 journal articles,
8 proceedings and 14 technical reports. He was a recipient of
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research grants from University of Ibadan Senate, West
African Rice Development Authority (WARDA), Belgian
Govt., Dutch Govt., and British Royal Society. He was
Visiting Scholar to University of Benin, University of Ghana,
Legon; University of Stirling, Scotland; Obafemi Awolowo
University, and Ekiti State University. He has been External
Examiner/Assessor of professorial candidates in many
universities within and outside Nigeria. He has successfully
supervised 13 Ph.D. Projects. .
Professor Ogunkunle was Dean, Student Affairs (1999-
2006) and Deputy Vice-Chancellor, Administration (2006-
2008).
Outside the University, Professor Ogunkunle was
Consultant to Food and Agriculture Organization (FAO) on
Integrated Soil Management (1998) and Application of
Framework for the Evaluation of Sustainable Land
Management (FESLM); Consultant to the Federal
Department of Agricultural Land Resources on Land
Evaluation (1985-1990); Collaborator, RCMD, UTA (1983-
2(00); Coordinator, UI/UTA Ayepe OFR Project (1990-
1993); Chairman, Visitation Committee, Bowen University,
Iwo (2011); Member of Governing Council, Bowen
University (2012 to date); Member, AGRA Committee for
Ph.D. Soil Science Curriculum in West African Universities
(2009); Member of West Africa Agricultural Productivity
Programme (WAAPP) Committee for Strategic Document for
a Road Map for Improving Soil Fertility in Nigeria (2014).
He is a member of the International Soil Science Society,
Soil Science Society of Nigeria, Agricultural Society of
Nigeria and. Remote Sensing Society of Nigeria; He is a
Fellow of .e Soil Science Society"of Nigeria (2009).
Professor Ogunkunle is happily married to Dr.
Oluwatoyin Ogunkunle and the marriage is blessed with two
sons and two grandsons.
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DAN LIBRARY
NATIONAL ANTHEM
Arise, a compatriots
Nigeria's call obey
To serve our fatherland
With love and strength and faith
The labour of our heroes' past
Shall never be in vain
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One nation boundin freedom
Peace and unity
o God of creation
Direct our noble cause
Guide thou our leaders right
Help our youths the truth to know
In love and honesty to grow
And living just and true
Great lofty heights attain
To build a nation where peace
And justice shall reign
UNIVERSITY OF IBADAN ANTHEM
Unibadan, Fountainhead
Of true learning, deep and sound
Soothing spring for all who thirst
Rounds of knowledge to advance
Pledge to serve our cherished goals!
Self-reliance, unity
That our nation may with pride
Help to l!)i~lda \\!Ort J "at 15 trulY free
Unibadan, first and best
Raise true minds for a noble cause
Social justice, equal chance
Greatness won with honest toil
Guide our people this to know
Wisdom's best to service turned
Help enshrine the right to learn
For a mind that knows is a mind that's free
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