Authors: Adedire M. O.
Bowen Journal of Agriculture. Vol. 2(2)
Abstract
Maintaining soil fertility is an important step in creating a sustainable agriculture. Although it is shown that /56 external chemical inputs are needed to achieve high crop yields, their availability and cost may be prohibitive for use in food crop production in many developing countries.
Agroforestry practices have been shown to positively influence chemical, physical and biological components of soil fertility and therefore increasing crop yields. The use of Sesbania species for fallowing for 2 to 3 years on N-depleted soil in Zambia increased the yield of subsequent unfertilized maize to 5 to 6 kg per hectare, compared with 1 to 2kg per hectare for continuous cropping of unfertilized maize. Trees in agroforestry systems can improve the nutrient balance of a site both by reducing unproductive nutrient losses from erosion and leaching and by increasing nutrient inputs through nitrogen fixation; they can improve soil structure, water-holding capacity and crop rooting volume; and they can increase the biological activity in the soil by providing biomass and suitable microclimate. This paper highlights and discusses the various agroforestry practices that could be easily adopted by small-scale tropical farmers in maintaining or regenerating soil fertility.
Keywords: Soil fertility, agroforestry systems sustainable agriculture