Nigeria is endowed with arable land and fresh water resources when viewed as a whole with approximately 61 million hectares of the land cultivable while the total renewable water resources is about 280 km3/year[1]; which include river Niger, river Benue, lake Chad, Osun river, Hadejia River, Bonny river and a host of others. Soil condition and water availability if effectively managed will help boost food production and address food crisis in the nation.

Soil

 Nigeria has a wide diversity of soil under different ecological conditions and with different levels of fertility. The different soils are a function of prevailing climatic condition, vegetative cover, and topography of the area among others.

The major soil types in Nigeria, according to FAO soil taxonomy legends are fluvisols, regosols, gleysols, acrisols, ferrasols, alisols, lixisols, cambisols, luvisols, nitosols, arenosols and vertisols. These soil types vary in their potential for agricultural use. None of these soils was rated as class 1 with high productivity by the FAO.

Nigerian soils can be classified into groups made up of four (climatic) zones that are soil associations. The groups are[2]:

1.       Northern zone of sandy soils

2.       Interior zone of laterite soils

3.       Southern belt of forest soils

4.      Alluvial soils Zones

   Map showing soil zones and types in Nigeria

  Courtsey: Kushimo oluwaseun

Northern zone of sandy soils: This area lies in the very northern parts of the country. This area lies in the extreme north with proximity to the fringes of the fast- encroaching Sahara desert. It is characterized by soils formed by deposition of sand by the wind. These soils might have been formed from wind-sorted desert sands that accumulated over long periods of time when the Sahara desert encroached several kilometers south of its present limits. The soils of this zone are very good in the production of groundnut, sorghum, cowpea, and millet.

Interior zone of laterite soils: This zone is made up of a mixture of sand and clay. They are grey to black clay, poorly drained and seasonally flooded forming the “fadama”. Soil in this zone is deeply corroded, generally sticky and impervious to water and has low fertility. When the virgin forest on them is cleared it reduces the fertility further, thus making the available soil of little agricultural value. However, not only laterite soils are found in this zone. The Biu Plateau has rich soil that is productive and offers prospects for the expansion of the areas of cotton production.

Southern belt of forest soils: Soils in this zone broadly represent those of the humid, tropical forest climate zones of the south where the wet season is long, the harmattan season short and forest cover is dense. Local soil types depend largely on parent rock; where the underlying rocks are granite or clay, the soils is a rich clayey loam. These soils are very good in growing crops like cocoa, oil palm, rubber and they are of considerable importance in Nigerian agriculture.

Zone of alluvial soils: These soils are found along the flooded plains of rivers, deltas, along the coastal flats. This zone extends from the coastal inland and runs along the valleys of the Niger and the Benue rivers, thus cutting across the vegetational zones. Soils in this zone are characteristic of fresh-water soil of grey to white sand, grey clay and sandy clay with humic topsoil. Another group consists of brownish to black saline mangrove soils, with a mat of rootlets.

Soil management

The traditional land tenure system and soil management practices involving shifting cultivation, slash –and-burn processes and traditional tillage method ensures the maintenance of soil physical properties and sustainable productivity. However, land use pressure has reduced the duration of fallow to restore soil fertility below the recommended minimum threshold required for sustainability (FAO 1985)[3].

Soil management practices includes

·         Cover cropping: This involves the planting of crops that help manage soil fertility, water, weeds, pests, diseases. It helps to reduce erosion, suppress weed manifestation etc. example include; Mucuna pruriens, centrosema pubescens,Pueraria phaseoloides.

·         Crop rotation: Alternating different crops with different nutrient requirement on a farm land in a predefined manner. It also help in replenishing lost nutrient e.g Nitrogen fixation by legumes.

·         Nutrient management: The use of organic manure, plant residues helps to improve the fertility of the soil and the amount of organic matter content, which also improve the soil structure and function.

·         Tillage: The practice of reduced tillage or no-tillage operation limits the disturbance of the soil and retains plant residues. This is very helpful on soils that are easily prone to soil erosion.