Gateway to Land and Water Information: Nigeria national report

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1. Country overview

1.1 Geography and administrative units

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1.1 Geography and administrative units

Nigeria is located between latitude 4oN to 14oN; and longitude 3oE to 15oE. It is bounded in the north by Niger Republic, in the West by Benin Republic and in the East by the Cameroun Republic. The Chad Republic is to the North-East and the Atlantic Ocean is to its South via the Gulf of Guinea. In [Map 1.1.1] is Nigeria located within Africa. The country got its name from its most prominent river, the Niger. Other dominant rivers and watersheds are the Benue, Cross Rivers, Ogun, Osun and Imo (all flowing directly into the Atlantic) as well as Rivers Kaduna, Hadejia and Gongola (all flowing into the Lake Chad).

Nigeria has a land extent of about 923,769 km2; a north-south length of about 1,450-km and a west-east breadth of about 800 km. It is a country with diverse biophysical characteristics ethnic nationalities, agro-ecological zones and socio-economy. Abuja is the capital and Lagos is the largest city and main commercial centre.

Nigeria has evolved over time and space in terms of administrative structures and nature of governance. It started as a mere amalgamated British colony in 1914 and became a federation in 1963. It became independent in 1960 as a 2-unit region comprising the Northern and Southern provinces. The additional Mid-Western region was created in 1963. The country was proclaimed a republic the same year.

The three (3) regions were divided into 12 units (i.e. states) in 1967 along with a number of sub-administrative units (i.e. divisions) for each state. The states were increased to 19 in 1976, 21 in 1987 and 30 in 1987.. Further changes in the administrative composition of the country include the redefining of the political regions as local government areas (LGAs) and the creation of the new Abuja Federal Capital Territory (FCT) on December 12 1991. With this, Lagos ceased to be the country’s capital, a position that it held right from before independence. There are now 744 LGAs. The states, their capitals and number of LGAs are shown in [Table 1.1.1]. The present 36 states structure emerged in 1996, with the creation of 6 additional states: Bayelsa, Ebonyi, Ekiti, Gombe, Nasarawa and Zamfara.

1.2 Socio-economic features

Nigeria is the most populous country in Africa. At the census of November 1991, Nigeria had 88,514,501 inhabitants and a population density of 95.8 inhabitants per sq. km. The average annual growth rate between 1963 and 1991 is 1.7%.

Based on the revised 1991 census results, the projected annual growth rate of 2.83 per cent by Nigeria's National Population Commission put Nigeria's population at 105.2 million in 1997. Available data showed that crude birth and death rates remained unchanged since 1992 at 49.0 and 14.0 per 1,000 persons, respectively. [Map 1.2.1] shows the population densities in the country vary considerably from 25 to 1500 persons per sq. km. [Table 1.2.1] shows some of the characteristics of the Nigerian population, while comparative population and demography data for Nigeria and the rest of Sub-Saharan Africa is presented in [Table 1.2.2].

The Nigerian population is divided among 478 different ethnic groups, some numbering fewer than 10,000 people. Of the different ethnic groups, ten groups: Hausa, Fulani, Yoruba, Ibo, Kanuri, Tiv, Edo, Nupe, Ibibio and Ijaw account for nearly 80% of the total population. Twenty-five percent of the population is in the former Western Region (12% of area), 21% in former Eastern Region (9% of area), 53% in former Northern Region (79% of area). The lowest population densities are found in the in the northern regions of Nigeria, especially in the states Borno, Adamawa, Kebbi, Kwara, Taraba, Yobe and Zamfara States. Forty-seven per cent of the population is below the age of 15 years.

Urban life has a long history in Nigeria with centres of population such as Kano (mid - 1975 estimate 399,000), Zaria (224,000), Ife (176,000) and Benin (136,000) dating from the Middle Ages. Recent economic development, however, has stimulated considerable rural-urban migration and led to the phenomenal growth of such cities a Lagos, Ibadan, Kaduna and Port Harcourt. The distribution of population between the 30 state structure existing as at 1991 is shown on the [Table 1.2.1].

[Table 1.2.2: Comparative Population and Demography Data for Nigeria and the rest of Sub-Saharan Africa]

Nigeria's economy has been dominated since the late 1960s by the export of oil, a sector dominated by the Government. By the mid-1970s, about 75% of Federal revenue came from petroleum. The share of exports accounted for by fuel, mineral and metals continued to rise and stood in 1991 at 96% (World Bank, 1994).

The development of the petroleum industry in the late 1960s and 1970s radically transformed Nigeria from an agriculturally based economy to a major oil exporter. Increased earnings from petroleum exports generated high levels of real economic growth, and by the mid-1970s Nigeria ranked as the dominant economy in sub-Saharan Africa and as the continent's major exporter of petroleum. Following the decline in world petroleum prices after 1981, however, the government became increasingly over-extended financially, with insufficient revenue from petroleum to pay the rising cost of imports or to finance major development projects. The decline in Nigeria's earnings of foreign exchange led to an accumulation of arrears in trade debts and of import shortages, which, in turn, resulted in a sharp fall in economic activity, with most of Nigerian industry struggling to operate without essential imported raw materials and spare parts. A series of poor harvests, an overvalued currency and a widening budget deficit compounded the problem.

However, the dramatic fall in international prices for petroleum in 1986, and reduced output in all sectors (except agriculture), kept the economy in the depths of recession. In July 1986 the government announced a two-year structural adjustment programme (SAP), which aimed at expanding non-oil exports, reducing the import of goods which could be manufactured locally, achieving self-sufficiency in food and increasing the role of the private sector. The SAP included the abolition of import licences and a reduction in import duties. The SAP was abandoned in 1994, following a severe deterioration in political and economic conditions in the early 1990s.

Economic instability was also reflected in a persistently high rate of inflation, which increased from an annual average of 24.0% in 1986-91, to a peak 72.8% in 1995. Between 1996 and 1998, however, the Nigerian economy as reported by the Federal Ministry of Finance, recorded impressive macroeconomic stability while it continued to show positive signs of growth. These included the exchange rate and the rate of inflation. The improved performance of the economy in 1997 was as a result of the sustained implementation of a sound fiscal policy dovetailed into an anti-inflationary monetary stance. Indeed, inflation rate decelerated dramatically to reach a 7-year low of 8.5% by end of December 1997.

Additional major economic indicators on the performance of the Nigerian economy for the period 1993-1997 is given in [Table 1.2.3].

Until Nigeria attained independence in 1960, agriculture was the most important sector of the economy, accounting for more than 50% of GDP and more than 75% of export earnings. However, with the rapid expansion of the petroleum industry, agricultural development was neglected, and the sector entered a relative decline.

Between the mid-1960s and the mid-1980s, Nigeria moved from a position of self-sufficiency in basic foodstuffs to one of heavy dependence on imports. Under-investment, a steady drift away from the land to urban centres, increased consumer preference for imported foodstuffs (particularly rice and wheat) and outdated farming techniques continued to keep the level of food production well behind the rate of population growth. After experiencing growth rates of 8% -10% per annum during the early 1970s, the increase in agricultural production declined to around 4% per annum towards the end of the decade. The slow growth continued into the 1980s, with output rising by only 3.4% in 1981 and by 2.7% in 1982. The effects of drought and the government's austerity programme resulted in severe 9.4% fall in agricultural output in 1983. However, succession of good harvests, higher producer prices, reductions in cereal imports and a resurgence of public and private investment in crop production resulted in a sharp recovery in production. Food output showed the strongest growth, rising by 7% in 1984 and by an estimated 10% in 1985, when total agricultural output increased by 3.8%. Agriculture was the only sector to show any significant expansion in 1986, with an estimated increase in overall agricultural production of 2.1%.

During the period 1981-94 the average annual growth of GDP was 2.3% compared to 4.6% for the earlier period 1970-80. [Chart 1.2.1] and [Chart 1.2.2] graphically show the contribution of agriculture to national productivity for the two periods 1984 to 1991 and 1993 to 1997 respectively. Average growth from agriculture from 1980 to 1992 was estimated to be 3.6% which compares favourably with an average of 1.7% for Sub-Saharan Africa; for the earlier period agricultural production in Nigeria declined by -0.1% (World Bank, 1994). Agriculture (including hunting, forestry and fishing) contributed 33.5% of GDP in 1993 an estimated 63.7% of the labour force were employed in the sector in that year.

Traditional small-holder farmers, who use simple techniques of production and the bush-fallow system of cultivation, account for around two-thirds of Nigeria's total agricultural production. The number of state farms is relatively small, and of decreasing importance. Since 1986 many of the loss-making parastatal bodies have been closed down or sold to the private sector. Subsistence food crops (mainly sorghum, maize, taro, yams, cassava, rice and millet) are grown in the central and western areas of Nigeria, and are traded largely outside the cash economy.

Agricultural output increased by an estimated 4.1 per cent during the year compared with the 3.7 and 3.5 per cent recorded in 1996 and 1995, respectively. At 42,930 million naira, the value of agricultural production constituted 38.7 per cent of the nation's GDP compared with the respective shares of 38.8 And 38.7 Per cent in 1996 and 1995. In spite of the continued satisfactory performance of the agricultural sector, it still fell short of the 5.5 per cent growth rate stipulated in 1997 - 1999 National Rolling Plan.

[Chart 1.2.1: Contribution of Agriculture to Nigeria's GDP at Current Factor Cost (In Million Naira)]

It is estimated that Nigeria has about 71.2 million hectares of available agricultural land about half of which is currently being utilised. Increasing rainfall from the semi-arid north to the tropical rain forested south allows great crop diversity, from short season cereals, sorghum, millet and wheat in the north to cassava, yams and rice in the wetter areas. In the drier regions cash crops include cotton, groundnuts and tobacco, while in the south cocoa, coffee rubber, oil palm, sugar and ginger are grown. Major food and cash crops production outputs for 1990 to 1997 are shown in [Table 1.2.4].

Traditional smallholder farmers, who use simple techniques of production and the bush fallow system of cultivation, account for around 2/3 of Nigeria's total agricultural production. Subsistence food crops (mainly sorghum, maize, taro, yams, cassava, rice and millet) are grown in the central and western areas of Nigeria, and traded largely outside the cash economy. Cash crops (mainly palm kernels, cotton, cocoa, rubber and groundnuts) are grown in the mid-west and north of the country.

A steady growth was observed in the agricultural production of both staple and other crops since 1990. At 234.1 (1984 = 100), the aggregate index of agricultural production increased by 4.1 per cent in 1997 (see [Chart 1.2.2]). In the same year, crop production rose by 4.3 per cent. All the major staples recorded significant increases over the preceeding years level. A national survey conducted by the Central Bank of Nigeria showed that the sustained increase in agricultural production as recorded in 1997 was in part due to the favourable weather conditions as rainfall was largely timely and well distributed throughout the country and on the other part due to the intensified effort by the National Agricultural Land Development Authority (NALDA) to bring more land/small holder hectarage under cultivation. Other factors which contributed to the improvement included the intensification of on-farm adaptive research by some relevant agencies, the supply of high quality seeds/seedlings and better usage of improved storage facilities. Estimates of production output for principal staple crops in 1997 were maize (6.3m tons), sorghum (8.0m tons), millet (6.0m. tons) and rice (3.2m. tons). Others include cassava (33.5m tons), yams (24.7m tons), potatoes (1.0m tons) and vegetables (3.8m tons).

Among the agricultural cash crops, only cocoa makes any significant contribution to exports. Nigeria was the world's fourth largest exporter of cocoa beans in 1990/91, with sales of 135,000 tons accounting for about 7.1% of world trade in this commodity. But, Nigeria's share of the world cocoa market has been substantially reduced in recent years, owing to ageing trees, low producer prices, black pod disease, smuggling and labour shortages Recent emphasis has been placed on encouraging domestic cocoa-processing to provide higher-value products for export.

Nigeria was also the world's leading exporter of palm oil, until overtaken by Malaysia in 1971. The production and export of oil palm products has declined dramatically and the country is now heavily dependent on imports in order to satisfy domestic needs. Like other cash-crop sectors, output of palm products has suffered from labour shortages, inefficient traditional harvesting methods, lack of vital inputs and low levels of capital investment. A sharp reduction in imports and large-scale re-planting, resulted in a substantial increase in production during the mid-1980s. Trade liberalisation and the exchange rate policies adopted in 1980's has also contributed to the improvement in palm oil production. There have been substantial investments in oil-milling facilities to produce vegetable oil for domestic use. Palm oil production was estimated at 730,000 tons in 1990, and increased to 837,000 tons in 1994. Production estimates for 1997 were put at 780,000 tons.

In 1990 Nigeria overtook Liberia as the largest rubber producer in Africa. Production rose from 55,000 tons in 1986 to 147,000 tons in 1990 and 255,000 tons in 1995. Output in 1997 was 250,000 tons. Benefits from a replanting programme in the eastern States have yet to materialize, and local demand from the tyre and footwear industries continues to outstrip domestic supply. A programme to increase output of rubber and palm kernels, with financial assistance from the World Bank, is being implemented.

Production of cottonseed increased from 276,000 tons in 1990 to 309,000 tons in 1997. Some of the reasons for the increase include considerable public and private investment in the sector, as well as incentives for local textile companies and higher tariffs on imported cotton.

Nigeria has enough land to support double its present population. Only 34 million hectares of the 71.2 million hectares of cultivable land is under cultivation. There are vast bodies of fresh water lakes and both fresh and brackish water lagoons which provide the bulk of the nations fish, the balance being from our 960 kilometer long coastal stretch.

The soils, rainfall, day length, the temperatures are adequate to support agriculture in one form or another throughout the country, although the northern fringes is progressively becoming sahelian, hence persistent crop failures is becoming the norm, and the livestock are migrating southwards irreversibly. There are also a few problem areas in the southeast sector where floods and oil pollution are disruptive to crops and fish production. If the soils are well managed, they will support agriculture for many generations in spite of their inherent medium to low fertility.

A discussion on food security of the country would be incomplete without an examination of the supply/demand equation of Nigeria's major staples as well as cash and export crops. It is however a subject most agriculturists feel uncomfortable to discuss because of the choatic situation of our agricultural statistics. Every source gives a different figure for each commodity.

As at 1985, the report of the study group set-up by government to examine the food situation of the country, showed that there was hardly a single food commodity in which the country can claim to be self sufficient. The total expected shortfall in local grains production was about 3.76 million tonnes per annum with an estimated increase in demand of about 4% per annum: the rate of grains production using 1983/84 production as a base, has to be above 10% per annum if shortages were to be eliminated by 1990 and thereafter. Today, given the available statistics, it doesn't seem the situation has changed that much, because with the exception of maize, demand for sorghum, millet, wheat and to some extent rice far exceeds the supply (see [Table 1.2.5]). In the case of wheat and rice, the Nigeria National Council on Agriculture (NCA) has as far back as 1994 approved the implementation of a strategy aimed at mass production of rice and wheat under irrigated agriculture. As at that time, the council observed that Nigeria has the potential of producing rice and wheat at least ten times the reported production levels, which were estimated at 3.56 million for paddy rice. Subsequently, a targets to produce a total of 6 million metric tonnes of paddy rice and 4 million metric tonnes of wheat during the 1995/96 dry season was set. The meeting suggested that the programme could be expanded to include other crops that do well under irrigation, such as tomatoes, vegetables and maize. As would be observed this target was never achieved.

In the case of roots and tuber crops, the report submitted that, the gap would be met within the short term if the rate of expansion in the cultivation of yams and cassava continues. This prediction has come true with the supply of cassava exceeding demand by over 9.6m tons in 1997. The committee also proposed that the country had a good chance of reaching self sufficiency levels for cow pea, if due advantage was taken of the expansion in cultivation of other food crops and the practice of mixed cropping and crop rotation were emphasized. Although, there still exist shortfall in supply of cow pea (0.4 million tons) as at 1997, the trend in production has shown remarkable progress. Similar progress in production has been reported in groundnut and soya beans where in the last five years supply has exceeded demand.

The export and industrial crops have suffered greater declines than food crops because government intervention measures such as supply of improved seeds and seedlings, agro-chemicals, processing, credit facilities, marketing and even credit were drastically cut during the past ten years. Secondly, food prices went up very sharply in face of real shortages, farmers therefore had no better choice than to devote most of their resources to food production.

Oil palm production has responded reasonably well to recent shortages and resultant high prices arising from the curtailment of the importation of vegetable oils. People return to the old groves which had been neglected, cut paths through them and harvested them, and used all available processing facilities to extract oil. There is also a new interest in plantation establishment by the industrial users of vegetable oils. If their approaches to the federal and state governments to buy equity shares and take over the management of existing oil palm estates and to obtain land for new ones succeed, significant increases in the production of palm oil will take place by 1990. We are also in the process of identifying new projects in oil palm with possible participation of the World bank and the International Finance Corporation.

Generally, the sustained increase in the agricultural sector as reported in 1997, was attributed to the favourable weather conditions, especially the timely and well distributed rainfall during the year. Also, the success of the National Agricultural Land Development Authority (NALDA) towards bringing more land/small holder hectarage under cultivation boosted agricultural production. Other factors that contributed to the agricultural performance were the intensification of adaptive research by some relevant agencies such as the Agricultural Development Project (ADPs), the wider supply of high, effective yielding seeds and seedlings as well as greater success at pest and disease control through the use of plant and livestock chemicals. In addition, the prices of Nigeria's agricultural commodities recorded significant improvements in the world market, reflecting increased demand.

In the late 1980s, Nigeria de-controlled farm prices, maintained subsidies on fertiliser and farm exports, and maintained import bans on some food items to encourage agricultural activity. Agricultural output rose slowly but not significantly due to inadequate transportation and power networks, lack of appropriate technology and the ineffective application of rural credit. The increased food production was not substantial enough to keep up with the growth of the population; therefore, the amount of food per capita dropped during this period.

However, the constraints that had hampered agricultural production in the past remained and even worsened in some cases. For instance, up to 1997, shortages in the supply of fertilizer persisted as production was reduced by 4.3 per cent from the 600,000 tonnes level in 1996 to 574,000 tonnes. The shortage was as a result of the removal by government of the fertilizer subsidy and the failure of the private sector to take full advantage of the privatisation/commercialisation of the fertilizer trade. The net effect of the removal of subsidy and supply short-fall was the sky-rocketing price of fertilizer which averaged 1,400.00 per 50kg bag during the year compared with the retail price of 200.00 per bag in the previous year.

[Table 1.2.5: Supply and Demand of Selected Agricultural commodities in '000 metric tonnes for 1995 to 1997]

Promotion of commercial agriculture with special reference to the crops sub-sector:

In recognition of the fact that small-scale farmers provide the bulk of the country's food required to supplement crop production for both food and industrial requirements, the Head of State and Commander-in-Chief of the Armed forces at the inauguration of the new Federal Executive Council on March 20, 1995 directed that the Federal Ministry of Agriculture should take appropriate action to develop commercial agriculture in the country.

An earlier study in 1994 commissioned at the instance of the Nigeria's Federal Department of Agriculture (FDA) revealed the following constraints to commercial agriculture among others:

The study confirmed that several arable and tree crops were suitable for large-scale production in different agro-ecological zones viz:

The memorandum enumerated Agricultural Service Institutions with mandate relevant to the promotion of commercial agriculture as follows:

In order to address the identified problems of commercial agriculture, the memorandum recommended the implementation of a National Commercial Agricultural Programme (NCAP). Activities to be supported under the programme include: land development; input sourcing as well as market information; credit -which could be in kind; marketing as well as provision of assistance in on-farm storage facilities; technical support and provision of appropriate curricula and provision of rural infrastructures.

In the south, abundant precipitation and relatively short dry seasons enables the growing of root crops such as cassava, yams, cocoyams, and sweet potatoes. Tree crops such as cocoa, oil palm and rubber constitute this zone's main commercial products. Cocoa grows mostly in the southwest, whereas oil palms predominate in the southeast and are numerous in the south-central area. Rubber stands are common in south central and Southeastern Nigeria. These different species are often inter-cropped with annual or arable crops in agro-forestry systems or as part of the tungya system in forest reserves.

Crops associated with the middle belt area include such staples such as yams, sorghum, millet, cassava, cow peas and maize, with rice in some commercial and irrigated areas. The southern edge of the middle belt represents the lower limits of the northern grain-dominated economy.

In the northern third of Nigeria which experiences a dry season of 5 to 7 months long, millet, cowpeas, and a drought resistant variety of sorghum, known as guinea-corn, are the primary crops. Maize is also cultivated, as well as rice in suitable lowland areas. The principal commercial crops in the north are cotton and groundnuts.

Fallow periods throughout Nigeria have experienced a reduction ranging from 40 to 60%. This is due in part to population pressures on the land, as well as the high cost of clearing bush for agricultural purposes.

Traditional cultivators throughout Nigeria use elemental irrigation systems long before the colonial period. The first government irrigation project brought 9000 ha under irrigation between 1949 and the end of the 1960s. The severe Sahel drought prompted the federal government and some state governments to invest large sums of money into irrigation development. As at 1997, available data from 8 River basins development Authorities (RBDAs) showed that a total of 7.8 million hectares were developed with about 4.4 million hectares brought under irrigation.

In general, Nigeria's climate permits the cultivation of a variety of crops, ranging from trees, grains and vegetables. The montane regions of Jos and Mambilla Plateau also supports such temperate crops as tea and apple. However it should be pointed out that the full potential of the country remains unrealised. The per hectare yield levels for all crops as shown in [Table 1.2.6] are considerably lower than what obtains in most parts of the world. Irrigated agriculture is still to be developed, despite the generally unreliable rainfall distribution in most parts of the country.

Much of the increase in agricultural output in recent years has resulted from expansion of the area under cultivation, rather than increased productivity.

[Table 1.2.6: Agricultural Yields by Major Crops (thousands of hectograms per hectare)]

1.3 Climate

Nigeria's climate is characterized by strong latitudinal zones which become progressively drier as one moves northwards from the coast. Rainfall is the key climatic variable and there is a marked difference between wet and dry seasons in most areas. By April or May the rainy season is underway in most areas south of the Niger and Benue river valleys. Farther north, rains do not commence until June or July. From December through February northwest trade winds, called harmattan, sweep across the country bringing moderate temperatures and lower humidity across the country. In addition, these winds are often laden with dust particles from the Sahara giving rise to characteristic harmattan haze that reduces visibility.

The annual rainfall total decreases from over 3,800 mm at Forcados on the coast to under 650 mm at Maiduguri in the extreme north-east of the country. The length of the rainy season also shows decrease from nearly 12 months in the south to less than 5 months in the north. Rain starts in January in the south and progresses gradually across the country. The period June to September is the rainiest throughout the country. In many parts of the south, however, there is a slight break in the rains for some two to three weeks in late July and early August. No such break occurs in the northern part of the country, and rainy season continues uninterrupted for 3-6 months. In the south, the heavy rains lead to severe erosion, low infiltration and high run-off in opened - up soils. On the other hand where infiltration rate is high the situation is that of high leaching, causing the development of inherently infertile soils with low cation exchange capacity (CEC) and low buffering capacity.

The regularity of drought periods has been among the most notable aspects of Nigerian climate in recent years, particularly in the drier regions of the north. Experts regard the twentieth century as having been among the driest periods of the last several centuries; the well publicized droughts of the 1970s and 1980s were only the latest of several significant such episodes to affect West Africa. At least two of these droughts have severely affected large areas of northern Nigeria and the Sahel region farther north. [Chart 1.3.1] shows the trend in the distribution of Rainfall over Nigeria during the period 1970 to 1994.

Nigeria has a climate, which is characterized, by relatively high temperatures throughout the year. The average annual maximum varies from 35ºC in the north to 31ºC in the south, the average annual minimum from 23ºC in the south to 18ºC in the north. On the Jos plateau and the eastern highlands, altitude makes for relatively lower temperatures, with the maximum no more than 28ºC and the minimum sometimes as low as 14ºC. The effect of these high temperatures is high evapo-transpiration and this eventually brings about water shortage for arable cropping. The soil temperature is also corresponding almost uniform in the country both during the day and at night, a condition in which only inherently low yielding grain crops can thrive.

The relative humidity is also high throughout the year, more so in the south. This responsible for the high incidence of pest in southern Nigeria. Anywhere the relative humidity's high has been found to be a very good breeding ground for pest. Another effect of this high humidity in the south and that of harmattan dust in the case of the north is plenty of cloud cover. This appears to be more noticeable in the southern states at the peak of the growing season, resulting in the reduction of the rate of photosynthesis is and low yield in crops.

The day-length is also not very favourable. In the country the variation in day-length is about 30 minutes from the north to the south. Thus the grain crops that require long day light for their yields are not producing at their best.

In conclusion, considering all the above natural environmental factors and the present varieties of crops we grow and our management practices, Nigeria at the present time can not boast of being the place where the highest grain yield in the world can be recorded or obtained.

In [Table 1.3.1] is presented additional agro-climatic data on eco-regional basis, while [Map 1.3.1] shows the mean annual rainfall pattern over Nigeria.

2. Land resources

2.1 Physiography

2.2 Soils

2.3 Agroecological systems

2.4 Wetlands, mangroves and inland valley bottoms

2.5 Inundation Land Types

2.6 Natural hazards

2.7 Land cover

2.8 Land use

2.9 Land use change

2.10 Land Productivity

2.11 Environmental Impact of land uses

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2.1 Physiography

Nigeria is a country with varying landforms as illustrated in Map 4. Although much of the country is dominated by plains, generally less than 609.5m above sea level, the eastern border with the Republic of Cameroun is lined by an almost continuous range of mountains which rise to about 2,419m The Chappal Waddi, the highest known point in Nigeria.

In the North, the Jos Plateau rises abruptly from a general level of about 609.5m in the Hausa Plains to an average level of some 1,219m but reaches 1,781.6m in Shere Hills. The area west of the River Niger is dominated by the plain, which rises gently from the coast northwards 'to the area of crystalline rocks where inselbergs rise abruptly above the surrounding plains. The Idanre Hills, the highest point of these inselbergs, rises to about 981m above sea level.

In general, the land surface of the country could be classified into three broad physical units or major relief features namely: the plains; the highlands; the troughs and the river valleys. Within each of these could be identified features of lower order. Only the plains have been discussed, because of their dominance.

The plains which are the dominant feature in the country have resulted from alternating denudational and aggradational activities. The African denudational surface high plains of Hausa land which are composed of crystalline rocks of the basement complex. They form wide plains dissected by mature valleys, an example is the Kaduna river valley. Above the plains are inselbergs and castle Kopjes which rise to over 904.8. The post-African younger denudational land surface is the main landform in the area of Pre-Cambrian to Cambrian basement complex rocks mainly granite gneiss, quartzite and schist west of the Niger.

This area is generally referred to as the western plains and ranges. Due to the folding of the rocks, they trend mainly in a North-South direction and typical landforms are the structural ridges and inselbergs protruding from an almost flat plains consisting of pediments, and sloping generally from the water divide between the Niger and the Gulf of Guinea from about 183m to 106.5m. The plains of this unit are of the post-African late Cainozoic denudational origin.

The Sokoto plain belongs to the post-African aggradational surface of the late Cainozoic age and is composed of sedimentary rocks of Cretaceous and tertiary age, namely, sandstones, shales and sands. The plain is about 244m to 304.8m above sea level.

East of the Jos Plateau lie the hills and the plains of Kerri-Kerri and Gombe which are composed of sedimentary rocks of tertiary age in the west and of Cretaceous age in the east, consisting mainly of sandstones and shales.

The plains merge northwards with the Chad Basin which is composed of young sedimentary rocks of Quarternary age. Modern aggradational land surfaces extend over the area which borders the southern margins of the western plains and ranges. It is composed of sedimentary rocks which are largely sandstones, shales, and clays of Cretaceous and tertiary ages. At Ewekoro, south of Abcokuta, these rocks are interbedded with limestone.

The most recent aggradational land surfaces lie further south along the coast of the Gulf of Guinea and comprise the coastal plains, islands and sandbars. These Quarternary deposits are sandy in the west and muddy in their eastern part. The plains extend into the Niger Delta, which is a swampy area of about 388 square kilometers and composed of the coastal plain sands and lignite series of Cainozoic age in its northern part and of alluvial mud in its southern part. The plain extends further eastwards across the river plains at the foot of the eastern highlands but is interrupted in the centre by the Awka-Orlu upland and the Nsukka- Okigwe Cuesta which is composed of resistant cretaceous sedimentary rocks and marked by two distinct escarpments. These escarpments are composed of false-bedded sandstones and coal measures.

The rivers of Nigeria can be classified into five drainage systems: the Niger system, the Benue system, the Chad system (a remarkable inland drainage system), the Cross and the Atlantic systems. Most of the rivers of the Atlantic systems are short, north-south coastal streams which follow through more or less regular courses. Apart from the Chad system of inland drainage, almost all the rest of Nigeria's river systems are exoreic (i.e., drain into the sea). The Niger and its major tributary the Benue are very outstanding (features of physical geography of Nigeria. They have not only punctuated the land surface of the Republic in a remarkable way but also greatly influenced the life of its people. Entering Nigeria from the northwest, the Niger flows for 1,271 kilometers (The National Atlas of the Federal Republic of Nigeria. First Edition 1978) reaching the sea in a series of distributaries. In the west, the western plains and ranges constitute the major divide which stretches from neighbouring Republic of Benin in a fairly simple line to near the Niger valley and separating the Atlantic-oriented north-south rivers from the right bank tributaries of the Niger. On the basement rocks of this unit, stream directions are largely controlled by the trend of the foliated' rocks and by jointing particularly on the more resistant rocks. This structural control is well displayed by the Ogun river, north of Olokomeji. Most of the rivers (Ogun, Oshun, Shasha, Yewa, Oluwa) are generally parallel but each individual river displays a dendritic pattern of drainage with its tributaries.

In the areas of coastal plains where the gradient of river valleys is very low, the rivers deposit their load, thereby giving rise to the formation of braided channels.

In the southeast, the irregular scrap of the Nsukka-Okigwe Cuesta forms the major divide separating the rivers that drain into the Niger and the Imo from those that drain into the Cross. Major rivers in this area, the Imo and the Cross, are oriented towards the sea while the Anambra joins the sea at Onitsha. The highlands of the eastern border form another water divide separating some tributaries of the Benue and Cross Rivers from those that flow into and through the Republic of Cameroun.

In the North, the central highland and Jos Plateau form a major hydrographical centre from which a radial pattern of drainage develops with streams draining to the Zamfara, Sokoto, and the Chad Basin. The major streams which drain into the Chad namely, the Yobe and its main tributaries, the Ngade, the Mbudi, and the Goma form a Centripetal pattern. Gradients of these streams are low and very little water ultimately reaches Lake Chad.

Most of the water is lost by percolation or by evaporation from the swamps and marshes, in which the streams loose them altogether. Lake Chad, of which only a part lies in Nigeria, varies considerably in area, which fluctuates with seasonal variations in climate.

2.2 Soils

The broad pattern of soil distribution in the country reflects both the climatic conditions and the geological structure; heavily leached, reddish-brown, sandy soils are found in the south, and light or moderately leached, yellowish-brown, sandy soils in the north. The difference in colour relates to the extent of leaching the soil has undergone.

Nigeria soils in general are highly weathered and have limited capacities for supplying the plant nutrient elements needed by crop plants. Often misleading is the tall and luxurant growth of trees which are easily noticeable but which in essence is not a reflection of high fertility. The nutrient content of the soil is, however, related to the geological structure. Over a large part of the northern and south-western areas of the country, the geological structure is that of old crystalline Basement complex rocks. These are highly minerlized and give rise to soils of high nutrient status, although variable from place to place. On the sedmetary rock found in the south-east, north-east and north-west of the country the soils are sandy and less variable but are deficient in plant nutrient. They are also very susceptible to erosion.

In general, the soils are light in texure and sandy. The clay contents ranged from 7% in Yandev to 43% in Arochukwu. In a soil survey carried out in 1982, of the 35 samples collected from all eco-geological regions of the country 29 samples had less than 20% clay. The effect of this on crop production is low moisture retention, rapid internal drainage and tendency for leaching of plant nutrients. Another detrimental physical property of most of our soils which was observed in the field is the extensive occurrence of gravel and gravel layers, often near the soil surface. These gravel layers occurred more commonly on soils developed from basedment complex rocks. They mechanically impede root development and appreciably reduce the production potential of many soils. However, it is generally agreed that by far the soil factor most limiting to crop production in Nigeria is fertility.

It has been opined that nearly all soils in Nigeria are deficient in phosphorus to some degree. In the case of K, the nutrient is low in the sandstones and related soils of the south eastern part of the country. There are reasons to believe that Cu and some of the other minor elements are also lacking in soils of several parts of the country. In general crop nutrient requirements include phosphate, sulphur and boron as well as nitrogen. Acid soils in the more humid areas may suffer from excess aluminium.

New problems in soil fertility management are continually arising some require refinement of present recommendations, where as, others present entirely new questions demanding immediate solutions. In Nigeria most of the problems are created by soil abusers in the form of:

All the above factors therefore, are threatening the existence of arable land and there is fear that if the abuses are not checked and brought under control, Nigeria's ability to feed hereself might be a mirage.

On the basis of the present farming systems the land area in Nigeria has been classified as follows:

There is a Report on the Soils of Nigeria published in 1990, based on field surveys that was undertaken in 1985.

2.3 Agroecological systems

The land cover or ecological zones delineated for Nigeria are based on those defined by KEAY (1949). Keay's ecological zones are primarily based on species assemblages and the amount of rainfall. It was found that northern and southern Guinea Savanna could not to south, the ecological zones were mapped as follows:

The savanna soils occur on nearly level to gently undulating-undulating/dissected plains. Their parent materials shales, basalts to Basement complex. Most of the soils are well-drained.

Class 1 Soils
There are no class 1 soils,. i.e. very good land with minor or no physical limitations to mechanical cultivation.

Class II Soils - Fairly Highly suitability (SI)
In this class are moderate to good land with few physical limitations to mechanized cultivation but which can be corrected.

These soils are found on nearly level to gently undulating plains with slope ranges of 0-2% and are derived from sandstone, shales and Basement complex materials. The soils are deep, well - drained. They have loamy sandy sand to sand loam surfaces underlain by sandy clay loam to sand clay subsoils.

However mapping unit 16a can be ground into IIw which is limitation due to poor internal drainage resulting to excessive wetness. The texture is also heavy due to the underlying parent material - basalts.

The class II soils cover about 244,949,33km2 (27.51%) in the country. The major crops grown in these soils include guinea corn, maize, maize, and vegetables.

Class IIs Soils - Moderately suitability (S2)
In this class are moderately suitable land with limitations such as moderate to shallow depth due to the presence of rock-outcrops and inselbergs.

The soils occur on gently undulating to undulating plains with scattered rock outcrops and inselbergs. The slope ranges are 2-6%; while the soils are derived from sandstone, shales and undifferentiated Basement complex. The soils are shallow to moderately deep and deep, well drained. They have sands to sandy loam surfaces underlain by sandy clay loam to sandy clay subsoils.

The soils of this class cover about 160,858,27 km2 or (17.38%) of the country land mass.

Class IIIe,s Soils - Marginal Suitability (S3)
In this class are fair to good lands that can be mechanically farmed with great care. There are moderate to high erosion hazards owing to undulating hilly dissected topography with scattered rock outcrops. Other limitations include shallow depth to iron-pan, concretions or stony/gravelly substratum.

This class includes mapping units 21b, 22b and 22c. The soils are found on undulating dissected plains with scattered rock out crops and hills.

The slope ranges are 6 - 13% while the soils are derived from sandstone and undifferentiated Basement complex and ironstone sheets.

The soils are shallow to moderately deep, well drained. They have sand to loamy sand surfaces underlain by loamy sand, sandy loam to sandy 1 clay loam subsoils. The soils of this class cover about 128,589.84km2 or 14.03% of the country land mass.

Class IVe,s Soils - Currently Not Suitable (N1)
In this class are lands not suited to mechanical cultivation but suited for limited clearing and land cultivation for the production of perennial crops. The soils commonly occur on hilly or steep topography. Soils are better used for forest reserve and wildlife.

The limitations include moderate to severe erosion hazards; steep or rocky slopes; very shallow depth and stoniness. Other limiting characteristics are slow permeability, low moisture holding capacity and poor capacity to utilise added fertilizers. The establishment of stringent erosion control practices is essential even when such soils are hand cultivated.

This class includes mapping units 23a and 24b. The shallow soils occur on dissected Plateau plains, hills and ridges. The slope ranges are 13 to 55%, while the soils the are derived from sandstone, shales and undifferentiated Basement complex.

The soils are shallow, well drained. They have sand to loamy sand surfaces underlain by bedrock.

The soils of this class cover about 244,949.33km2 or 27.51% of land area of Nigeria.

[Text 2.3.1: Soil Fertility Initiative]

Power point report (zipped 304kb) on Nigeria's soil fertility initiative.

2.4 Wetlands, mangroves and inland valley bottoms

2.5 Inundation Land Types

Definition: Inundation land types can be defined as areas or a portion of the land that are seasonally, constantly and annually or yearly inundated or flood prone or subject to flooding. There are basically three types of inundation areas in the country namely:

Seasonally inundated land types:
These include the Lower Niger valley around Asaba / Upper Onitsha and the Sokoto - Rima valley.

Yearly/Annually inundated lands:
These are localised within the Niger delta under the influence of black flood

Perennial/constantly inundated lands:
This is limited to the Benue valley (spanning for about 22,000 sq. m)

2.6 Natural hazards

The major hazards being experienced in Nigeria includes land degradation, flooding, erosion, deforestation, desertification and climatic drought.

Degradation refers to the general lowering of the surface of the land by erosion processes, especially by air, water and wind, the last two being the most significant. Degradation also involves the lowering through transportation of the quality and quantity of land resources to the detriment of humankind. Land degradation in the country is caused by both natural and artificial (man-made) factors, particularly the latter.

In Nigeria, construction related bulldozing and mechanical tillage (ploughing) subject the soils to devastating processes such as erosion and the formation of hardpans. In the Sudan-Sahelian region, overgrazing poses a serious threat also contributing to the process of desertification and wind erosion. This came to a peak during the recent prolonged drought of about 10 years (1970-1980). Also, deforestation, whether resulting from the demands of animal husbandry, the cutting of wood or the incidence of bush burning, usually produces soil degradation and infertility.

Erosion poses the greatest threat to Nigerian soils and affects over 80% of the land. Wind, sheet, gully ([Photo 2.6.1]), mud and beach erosion affect different parts of the country in varying intensities. They are all menace to agricultural land uses.

While wind erosion is confined to the arid north, sheet erosion is ubiquitous throughout the country. Areas most prone to sheet wash are areas where farming has cleared the original. Vegetation, and the soils being impoverished, become scrub-land. But gully erosion is by far the most alarming type of erosion in Nigeria, because it often threatens settlement and roads. Although it affects a small fraction less than 0.1% of Nigeria’s 923,800 km2 of landmass, gully erosion is claiming large amount of pubic funds annually for remedial action.

Flooding refers to the abnormal rise in the stage of a river or water bodies. Flooding in Nigeria has been due to natural and artificial factors. The unevenly distributed rainfall in term of amount of duration, and the climatic variability resulted in abnormal runoff generation, which the channel’s capabilities cannot hold.

Flooding has been experienced in the Niger through Benue basin and Sokoto-basin in the flooding years of 1987, 1991 and 1994 and this affected agricultural landuse to a great extent. On the other hand the ocean inflow in Victoria island and that of Ibadan urban areas by Ogunpa stream have affected urban areas.

On river Niger (there are) two distinct floods occurring annually in the river. The first is the black flood that originates from the high rainfall area in the headwaters. The black flood arrives Kainji (Nigeria) in November and last until March at Jebba after attaining a peak rate of about 2,000m3S-1 in February Oyebande et al 1980. The second flood, which becomes prominent only downstream of Sabon Gari soon after the river enters Nigeria, is the white flood usually heavy laden with silt and other suspended particles. The flood derives its flow from the local tributaries and reaches Kainji in August in the pre-Kainji Dam River Niger and attaining peak rates of 4,000 – 6,000m3S-1 in September – October in Jebba.

A prolonged drought has also been experienced in Nigeria between 1970 and 1980 and this affected agricultural production of the northern part of Nigeria. The drought during this period also resulted into loss of cultivable land to desertification.

There have been some control methods adopted and some of these are effective in controlling these natural hazards. In the control of erosion, the planting of trees in savanna region of the country has been adopted. Also in the prevention of bush burning, planting of cover crops and the construction of barriers to stop water from eroding the topsoil in the gully region of the southern-eastern region has been adopted. However, these have not been highly effective.

Flooding on its own part has been controlled by the construction of dams to store the excess water. The demolition of structures along the stream/river banks has also been used and these have been highly effective.

The drought problem has been less controllable due to the interference from man and his actions.

2.7 Land cover

Land cover describes the natural features covering the land surface of an area. It is used as the principal surrogate for interpreting man’s activity and interaction with land.

Thus, based on the observation of land cover as a proxy, one hopes to infer human activities and land use. However, there are human activities that may not be directly related to the type of land cover, such as recreational activities. Other problems include multiple use, which may occur simultaneously or alternatively, vertical arrangement of uses and the minimum area size of mapping and inventory.

Broadly, the vegetation over a geographical area is essentially a response to the climate of the area. Nigeria’s vegetal belts correlate closely with climatic (rainfall) regions. Rainfall still remains the single dominant factor influencing the natural vegetation distribution of Nigeria. As a result of the progressive decline in total rainfall from the south to the west and the variation in the length of the wet season, vegetation belts are demarcated on west to east zonation pattern characterised by transitional zones from one belt to another.

Nigeria has two broad belts of vegetation types, namely; the forest and the savanna types. Each of the two belts are further sub-divided into three types viz.

These classes are embedded in the vegetation and land use legend developed for Nigeria by the Forestry Management, Evaluation and Co-ordinating Unit of Nigeria's Federal Department of Forestry. This is embodied in the accompanying Table.

2.8 Land use

Seven major land use types have been delineated for Nigeria. These are Urban, Agriculture, Woodland / Shrub / Grassland, Forest, Wetlands, Water, and Bare Surfaces. The maps and Detailed descriptions are obtainable from the Forestry Management Evaluation & Co-ordinating Unit, Federal Department of Forestry. Abuja.

Generally, agricultural areas in Nigeria have increased by 84,073km² (9%) between 1976/78 to 1993/95 ([Table 2.8.1]). Much of the agricultural growth is a result of land use intensification associated with population increases, and has occurred in areas of less intensive use or in relatively natural lands, such as savanna, forest or swamp. The greatest increase associated with this process occurred between 1990 and 1995, with an increase of approximately 6.9m ha.

There was a steady increase in the extent of floodplain agriculture (fadama) from 1978 through 1995 ([Table 2.8.2]), with the amount of floodplain agriculture more than doubling. This took place mostly as a result of the transition of wetlands to agriculture use. Considerable World Bank funding went into developments of fadama projects over this period.

Continuous and discontinuous grasslands are the transition between natural savanna vegetation and bare ground, or between natural savanna vegetation and agricultural land use. The largest increase in this class occurred between 1990 and 1995 where the area of grassland increased over one and half times from approximately 2.0m ha to 3.2m ha.

Areas dominated by trees/woodlands/shrubs (guinea vegetation) decreased by 50% during the study period, with the majority of the area converting to agricultural use in the 1990s. Between 1986 and 1990, this area declined significantly, by 3.1m ha and between 1990 and 1995, the amount of area declined by a further 3.3m ha. Not only is the decrease significant but there was an increase in fragmentation too.

The areal extent of areas dominated by shrubs and grasses (Sudan vegetation) remained stable until 1986, however by 1995 it had decreased approximately by 40%. Specifically, between 1986 and 1995, the extent decreased by approximately 6.1m ha, with a decrease of 4.1m ha between 1990 and 1995. This was largely due to impacts associated with grazing, fuelwood collection and the establishment of smallholder agriculture. As a result, there were very few areas of dominantly shrubs and grasses remaining.

The amount of land mapped as dominantly grasses (sahel vegetation) remained relatively constant from 1978 through 1995 ([Table 2.8.2]).

Land designated as forests have experienced a significant decline between 1978 and 1995. Specifically, 2.2m ha of the forest were converted, primarily to agriculture, during that time frame. Of significance was the fragmentation and decline of forest in western parts of the country, in Taraba, Cross River and Benue states. As well, there appears to be a transition of lands designated as forest in the southern areas of Ondo and Edo states to forested freshwater swamp, mangrove forest and agricultural designations.

Areas of land designated as mangrove have remained relatively constant. Likewise, areas of forested freshwater swamp remained relatively constant until 1990. However, since 1990, significant areas of forested freshwater swamp have been drained for agricultural purposes. As a result, areas of forested freshwater swamp have decreased from 2.1m ha in 1990 to 1.8m ha in 1994.

By 1990, the majority of freshwater marsh and swamps along the Niger, Benue and Hadejia rivers had all but disappeared. These lands were being utilized for floodplain agriculture. The areal extent of Lake Chad also remained constant until in 1990. However, by 1994, its shoreline had receded and the extent of floodplain agriculture along the Hadejia River had decreased. Since this time period, a new dam and reservoir have been constructed south-west of Kano on one of the tributaries that drain into the Hadeija River, and therefore into Lake Chad.

There was a dramatic increase in the area of water from 148,000 ha in 1978 to 680,000 ha in 1995. The largest increase in area appears to have occurred between the 1983 and 1993 time periods.

Areas of erosion/bare soil started to become more prevalent in 1986. From 1986 to 1995, there was a noticeable progression from areas dominated by trees and shrubs to bare soil. In the areas dominated by trees and shrubs, the trees and shrubs were removed, probably for fuelwood, leaving behind the grasses. The remaining grasses were not able to stabilize the soils, which resulted in erosion. Consequently, grassland areas converted to areas of bare soil.

Bare surfaces increased nearly twenty times between 1978 and 1995. The largest increase in bare surfaces occurred from 1986 to 1990, an increase from 0.4m ha to 1.4m ha. Throughout Nigeria, there is clear evidence that land use is intensifying under the influence of population growth and low rainfall in the north. Given uncertain land tenure systems, unavailability of fertiliser, and lack of extension advice for low-inputs systems, these processes of intensification are generally accelerating the rate of land degradation.

[Table 2.8.1: Dominant Vegetation and Land use classes in Nigeria and the changes in Areal Extent between 1976/78 and 1993/95]

[Table 2.8.2: Changes in the Areal extent of vegetation and land use types (1978 to 1995)]

In the south, with its very high rural population densities and small average farm sizes (0.8 ha in the south-west and 0.3 ha in the south-east), intensification takes place largely through shortening of a fallows, leading to a decline in fertility. A survey of Imo State indicated that over a 20-year period, fallow periods had declined from 1 - 9 years to 0 - 6 years - much less than the 5 - 7 years necessary to restore fertility as well as low yields. The decline in fallow periods had reduced capacity to supply stakes, fodder or browse, foodstuffs and medicines. Farmers then had to purchase these requirements or deforest other areas. Some highly degraded areas suffer from extreme erosion or become colonised by spear grass and become completely useless. In some villages of Anambra State, the Land Use Intensity Index (the ratio of cultivated land to cultivated land plus fallow) is 80%. Especially in upland areas, intensification causes loss of organic matter and nutrients, and structural deterioration.

About 12% of the northern fringe of Nigeria is threatened by the encroaching Sahara desert. The sand dunes that were once stable are now exposed through increased wind activity on increasingly bare surfaces. Large areas of gully erosion are clearly visible, and denuded areas can be identified in many agricultural regions of Nigeria.

The increasing intensity of agricultural activity due to population growth may be the most important factor influencing this process. Additional factors may be the change to a drier climate coupled with the establishment of major water works projects (i.e., construction of dams).

2.9 Land use change

2.10 Land Productivity

2.11 Environmental Impact of land uses

3. Water Resources (AQUASTAT)

3.1 Hydrography

3.2 Irrigation and drainage

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3.1 Hydrography

Water is an inevitable resources needed for sustainable development. In fact the level of civilization and development of any geographical unit is a function of availability and the level of sophistication employed in the distribution/supply of its water resources. Nigeria from the almost inexorable water potential in the south, particularly in the Niger-Delta to almost non-available in some parts of the sahelian in the north, its distribution poses some difficulties for its multi-faceted developmental purposes.

Water is available on earth surface in various sinks such as lakes, rivers, dams, ponds, and streams, etc. Nigeria has been divided into eight hydrological zones by the Water Resources Department of the Ministry of water Resources as presented in [Table 3.1.1].

Apart from Lake Chad hydrological area where the surface water flow into Lake Chad, the surface water flowing from Nigeria to the sea is estimated at around 263 km2/year. The density of the inherent drainage networks in each of the zone decreases from the south to the north (Oyebande, 1993).

The regime (pattern of seasonal variation which tends to be repeated from year to year) of rivers in the western littoral, eastern littoral, Niger south (except River Niger), upper and lower Benue (except River Benue) immediately after the raining season, and a low water period corresponding to the dry season. The Niger north (except River Niger) and Chad Basin rivers systems drainage channel characterised by torrential regime in which flow are intermittent, occurring mainly during the short rainy season. The Niger-Benue which are the two principal rivers system in the country has a higher complex river regime typical of tropical rivers and characteristics of most of the world’s large rivers.

The implication is that, in area of first category (simple regime) if volume of flow is adequate and sufficiently stable under the natural condition the simple regime of the stream makes the harness of the water resources cheaper without incurring large expenses on complex regulatory structures. This is in contrast to the intermittent rivers with erratic flow regime and insufficient water thus requiring a large expanse for complex regulatory structures for development purposes. The Niger-Benue are large water bodies with complex regime thereby needing a high level technological manpower and high cost for control programmes. In general, the more simpler a river regime is, the less storage capacity is needed to be provided in order to maximize available yield or runoff.

[Table 3.1.2] shows the annual runoff and specific yield of the major river systems in the country. It is a good summary of the surface water resources potentials. The specific yield which is the discharge per unit area of the basin above the station gives clear indications of humidity or aridity of the basin, the higher the rainfall, the higher the specific yield.

The availability of ground water in any area is a function of accumulated reservoir over years and the seasonal replenishment. Where ground water abstraction exceeds replenishment over time it will lead to ground water mining and this will deplete the ground water. In the south, regular seasonal large scale replenishment due to high and double maximum rainfall reduces the change of large scale depletion of the aquifer except in large urban centers such as Lagos.

In the north where annual rainfall and recharge are both small and variable over exploitation that have actually lead to ground water mining have been identified in some areas such as Katsina and Daura in the Tagwai El-Fadama sub-basin where more than 40 bore-holes have been sunk.

A total of some 142 dams made up of 60 large ones (height >15m) and 82 small and medium ones have been constructed or are under construction. The 108 large and medium dams have a total capacity of 26.3 x 109m3. The large-scale dam projects are concentrated (857) in the five northern and central areas for perennial storage of wet season runoff to be released later for dry season irrigation. In all the water resources is mobilized for multi-purpose uses such as for domestic water supply, irrigation, etc. The amount of water that goes to a particular use or for a group of people or region or state is a function of many variables among which availability and government play a dominant role.

Up till 1995, a total active reservoir capacity is 303km3. Water allocation from reservoir is shared as follows: 10.9km3 (36%) for irrigation, 0.8km3 (3%) for water supply and 18.6km3 (61%) for hydropower. Agricultural, domestic and industrial water withdrawal was estimated at 3.6km3 in 1987. Except in special cases water treatment and reuse is not a common phenomenon. In all, Nigeria is endowed with abundant water resources. Per capital share of surface water alone is at the order of 3.000m3 per annum. Areas deficient in surface water (e.g. Sahelian zone) or whose surface water is contaminated by saline intrusion or oil pollution (e.g. Niger Delta) are adequately compensated with ground water. The lower reliability of the runoff resulting from the variable regime however, necessitate flow regulation by dams. There is need to plan and design such dam on the basis of adequate hydrological data and in coordination with upstream riparian states who control what reaches Nigeria from major rivers and lakes basin such as the Niger, Benue and the Chad.

[Table 3.1.2: Available Surface Water Resources for Some Selected River Station]

3.2 Irrigation and drainage

In the light of the combined use of surface water and shallow fadama aquifers, irrigation potentials in Nigeria are made particularly difficult. Yet, according to the national water resources master plan study, total irrigation potential of the country is about 3.14 million ha: 1.10 million ha for public irrigation projects and 2.04 million ha for formal fadama irrigation projects ([Table 3.2.1]). Other sources estimate total irrigation potential to be about 2 to 2.5 million hectares.

The major places of irrigation are found in the Sahelian region of the north especially in the Sokoto-Rima basins and the Lake Chad area. Other places include the north central (Hadejia area) and some parts of the middle belt. Only about 4% of the cultivated land area is under irrigation. Estimate of irrigated cropland varies from one source to the other but its total water managed area is estimated to be a little over 950,000 ha. This yields about 10% of the national crop yield.

The trends in irrigation schemes in Nigeria can be traced from the subsistence agriculture which characterised family effort to the period when animals were used to transport water to farm plots. In recent times, large irrigation projects supported by co-operatives, government and international organisations are evident resulting in the following irrigation systems:

In floodplains areas, the origin of irrigation water account for about 10.5%, reservoirs 21.1% and pumping in rivers – 68.4%. The major irrigation methods are

In terms of techniques, account for just about 2.2% while surface irrigation is about 97.8%.

A little above 57% of large irrigation schemes are actually put into use. In area of small scale schemes, a slight increase (about 60%) is recorded. While the large scales are always under government control the small-scale are mostly formerly-owned but with some assistance from the government in terms of subsidies and training. Meanwhile, about 76% of the total water managed area are residual where no government aid is supplied.

The part of the equipped area actually irrigated by pumping from rivers or groundwater is 121.161 ha representing about 13% of the total water managed area, sprinkles irrigation is on 3,570 hectares.

The average cost of irrigation development is estimated at $1515,000/ha (in 1993). This however, might have increased drastically. Annual operation and maintenance costs have also varied between $50US/ha for gravity system and $290US/ha for pumping systems to $800US/ha for sprinkles irrigation systems.

Coupled with on adequate use of fertilizer, production has increased to more than 100% of what could have been adhered hitherto. The main irrigated crops in other of significance include rice, vegetables, wheat, potatoes and tobacco.

Nigeria is a member of two regional authorities dealing with water resources management; the Niger Basin authority and the Lake Chad Basin Commission. The highest national water resources policy formulating body is the National Council for Water Resources chaired by the Federal Ministry of Water Resources. It is organised in eight departments of irrigation and drainage to promote the development of irrigated agriculture through the existing river basin development authorities.

The Federal Ministry of Agriculture and Natural Resources is involved in irrigation development through the Agricultural Development Projects (ADPs). The ADPs promote farmer owned and managed irrigation schemes, provide extension services for farmers on public irrigation schemes and are assisted by the Federal Agricultural coordinating unit. In some states, the Ministry of Water Resources has been created and the Federal Competence in irrigation via the Ministry of Agriculture and Natural Resources have been transferred to them.

Nigeria is a country where population will exceed the carrying capacity of its land resources if cultivated with low level of technology. To increase productivity, therefore, the use of fertilizers and improved irrigation are viewed as key factors.

A number of problems exist in the irrigation sub-sector. Large public projects are hampered by very high cost of irrigation development, and by the inadequacy of planning and design of the command areas (viz. lack of available water downstream, no provision for irrigation services) and the irrigation canal system itself. These and a slow achievement of target yield, lead to poor financial returns to the small-scale farmers in large scale irrigation projects. In small public projects, lack of training and extension is considered a major constraint to achieving the target incomes, together with unreliable supply of agricultural inputs.Traditional informal irrigation suffers from the changing hydraulic regime of the flood plains (fadama) due to the construction of dams and other structures upstream. Reservoir construction also generates social problems, principally due to their implicit displacement of populations.

Improvement in the irrigation sub-sector requires clearer and more appropriate policies and programmes. Major involvement of adequately trained farmers; availability of fertilizer and seedling of adequate quality; and an increasingly farmer-owned and operated irrigation system are required. However, the floodplains of the Niger River is considered the greatest untapped potential for future irrigation development in the country.

4. Plant nutrient resources

4.1 Plant nutrient use and nutrient balance

4.2 Fertilizer production and costs

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4.1 Plant nutrient use and nutrient balance

Three macro-nutrients including nitrogen, phosphorous and potassium (NPK) are considered the major primary elements of plant nutrition in Nigeria. As such, most of the fertilisers commonly used by farmers in the country contain at least one of them. The plant nutrients vary from one soil type to the other. This determines the specific type of crops planted on the soil of an area in the country. For instance, cash crops like cocoa and kola-nut; and food crops like yam and cassava thrive well in the western part of the country while such cash crops like groundnut and cotton; and food crops like cow-pea and sorghum are planted in the north. Towards the east are such cash crops like rubber and palm produce; and food crops like cassava.

In the same vein, the types of deficient plant nutrients vary from one area to the other based on the soil type and the type of crops planted in such area. For instance, nitrogen deficiency is more common in the north. As a result, such crops that contain nitrogen are used there. However, this is not to say that other plant nutrients are not essential too in the west and the east because of the organic matter content formation, the type of plant nutrient used is dependent on the deficient nutrient of the particular soil condition and the crop.

Due to this, the trends in plant nutrient use vary from one region to the other. While large quantities are needed in some areas, small amounts are required in others. This is equally enhanced by the micro-climatic conditions. Considering the present variation in climate and the attendant result of soil formation, it can be projected that the harsher climatic conditions in every part of the country will imply that most variety of nutrients will be needed in different parts of the country. Also, the fast approaching aridity now extending towards the south coupled with human activities like bush burning, over cropping, overgrazing and deforestation constitute to the reduction in soil fertility thereby making the use of fertilizers unavoidable.

This can be looked at based on the critical values fixed for available NPK in certain tropical countries. These critical values can then be taken as a guide for the rating of soils into low, medium and high. The percentage of organic carbon (O.C.) present in the soil has been taken as a base for arriving at available nitrogen in the Nigerian soils as presented by SARDA, land (1989) and shown in the Table.

Different types of fertilizers are produced locally while some others are imported. Apart from the organic fertilizers (i.e. manure), various types of inorganic fertilizers are also produced. Inorganic fertilizers are mainly super phosphate, NPK and nitrogenous fertilizers. Organic ones are mainly animal droppings and livestock droppings.

The impact of fertilizer use on the environment can be said to be multi-dimensional. Generally, it can cause pollution of the underground water via the leaching of the fertilized soils.

Often, fertilizer application can weaken the biological composition of the soil, thereby inhibiting the biological processes that naturally add fertility to the soil. As such, it can lead to an environment not being able to sustain plant growth without adding another batch of the input. For the proper growth of plants therefore, the plant nutrients being added should be adequately measured neither should it be too much nor too low.

In a situation when there is nutrient imbalance, it has some effects on the soil fertility. Firstly, too much of such nutrients may kill some micro-organisms that enhance aeration of the soil. Secondly, too little of such nutrients may lead to reduction in soil fertility. In the two cases, it may also lead to stunted growth of plants and crop failure.

The application of mixed fertilizer would add to the fertility of the soil if it is added in considerable measures, thereby improving the condition of such soil in the environment. This would in turn lead to proper growth of plants and good yield. However, soil tests that need to be carried out for every part of the country to be able to ascertain which soil requires which type of fertilizer and in what quantity are often lacking. This constitutes a main hot spot relative to fertilizer application.

4.2 Fertilizer production and costs

5. Hot spots

5.0 Overview: constraints to sustainable agriculture

5.1 Land-related constraints

5.2 Water-related constraints

5.3 Plant nutrition-related constraints

5.4 other constraints

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5.0 Overview: constraints to sustainable agriculture

The issues of concern to sustainable agriculture in Nigeria include but not limited to problems of soil vis-à-vis human induced soil degradation (such as deforestation, bush burning and soil compaction). Also included are landuse issues and biodiversity depletion, risk and water use issues.

5.1 Land-related constraints

The problematic soils in Nigeria are those that are uncultivable or made uncultivable owing to human-induced degradation processes. Two soil types are common in this direction, viz:

The hydromorphic soils of the extensive Niger delta basin, covering about 70,000 km2 (Plate 5)
The extensive laterite soils underlain by the basement complex that cover largely the extensive middle belt area.
While the former requires massive capital investment to reclaim and/or work on the extensive wetlands via water control structures, the situation has been made even more difficult by increasing oil spillage that are occurring daily in the delineate environment. Even the few areas where agriculture is practicable has been rendered unproductive by oil spillage and effluent discharges.

In the latter case, the lateritic soils with granitic layers in some places require massive investment in both organic and inorganic fertilizers to make the soils productive. Also, because of the harsh climatic environment, massive investment is also required in agro-chemicals to pave way for the high and sustainable agricultural yield in the zone.

The most common huma-induced soil degradation practices in Nigeria are: Deforestation, Bush burning and improper agricultural practices.

Deforestation is pronounced in the rainforest zone of the eastern and western Nigeria. This tend to open up the lands for soil degrading catalysts such as water erosion and flooding with its attendant washing away of the fertile top soils as well as leaching. The situation is more pronounced within the Guinea savanna area. In the case of the savanna area of the middle belt, deforestation is combined with bush burning to open up the already sterile soils for further degradation, thereby paving way for further reduction of fertility, agricultural productivity and yield per area.

Improper agricultural practices are common in every part of the country. Soils are not adequately protected by cover crops as crop rotation is hardly practised. Over-farming of fragile soils has worsened the problem of soil degradation. Even in the west and eastern areas where bush-fallowing is practised, little consideration is given to land maintenance during fallow periods.

In Northern Nigeria, deforestation and bush burning have enhanced further desertification. This has resulted in further loss of potentially arable lands. The mapping of lands by herd animals (especially cattle in the process of transhumance also tend to lead to soil compaction and nutrient decline. It has also resulted in the destruction of crops especially in the Guinea Savanna area of Nigeria; with its attendant friction between farmers and cattle rearers.

In Nigeria, much attention is focussed on urban land use relative to that of the rural area. So, while land use in urban areas is regulated by the government, the rural areas is characterised by free holding through both inheritance and land tenure.

The alarming rate at which prime and productive agriculture lands at the fringes of urban centres are being lost to physical development has a very significance implication for future food security in the country.

An investment in agricultural lands, away from the urban periphery in form of feeder roads and agricultural inputs is still a subject that requires better consideration to forestall future shortage in food security especially in the wake of transportation problems from the rural areas. In spite of the land use decree which empowers the government to be land owner, the present policy whereby individuals have more power on land than the government needs to be revised to pave way for improved investment in agriculture by wealthy individuals and corporate organizations.

5.2 Water-related constraints

Water use in Nigeria are mainly for agriculture, domestic, industrial uses. Agricultural water use includes, irrigation, livestock watering. Considering the available water resources vis-à-vis water demand, a very efficient water use and allocation policy needs to be evolved for sustainable water development. Such a policy should seriously consider water recycling between the difference water uses. Presently, about 313,7000ha of land is put under irrigation by RBDAS shown in Figure 11. This represents only 5.4% of the total cultivate land in the country.

There are about 60 large dams and 100 small dams (called ADP dams); all providing water for agriculture.

There have also been conflicts in water use for HEP generation and agriculture. Dams are often `shut-off'’ during low flow, thereby starving the downstream agricultural areas. Nigeria is a member of the Niger-Basin Authority and Chad Basin Authority. The two agencies have international status consisting of all countries at the basin of the respective water bodies. These consider issues relating to allocation, development and use of water in the respective basins to forestall international water conflicts.

5.3 Plant Nutrition-related constraints

5.4 Other constraints

Nigeria is diverse and so has climates ranging from the extremely wet humid equatorial type to the hot dry arid characteristics. This accounts for the abundance of plants and animals species in the country. However, due to deforestation and the prospecting for mineral and oil resources, some of the biotic resources are being increasingly depleted. Woods such as Iroko, Mahogany, Oak, Walnut etc are being felled and exported to countries of Europe and even America. These also have tremendous negative effect on agriculture

Critical Values of Soil Nutrient in Nigeria
Nutrient Status	Low	Medium	High
Available nitrogen	<p.5% (o.c)	0.5 – 75% (o.c.)	>75% (o.c)
Phosphorous	<20kg/ha	20-40kg/ha	>40kg/ha
Potassium	<115kg/ha	115-275kg/ha	>275kg/ha
Source: Sokoto Agricultural. & Rural Development Authority, Land Use Planning Department, 1989