Soil fertility – the capacity of the soil to supply nutrients to a crop – is critical for smallholder farmers to feed themselves and increase their incomes.
Soils in Africa, like so many of its people, are hungry. Soil nutrient depletion and population increases have caused per capita food production to decrease over the past 30 years in sub-Saharan Africa. African farmers have traditionally cleared land, grown crops for a few seasons and then moved on to clear more land. This practice left the abandoned soil fallow, allowing it to regain its fertility. But constant population growth now forces farmers to continually plant crops on the same land, “mining” the soil while giving no nutrients back.
Integrated soil fertility management (ISFM) is a set of agricultural practices adapted to local conditions to maximize the efficiency of nutrient and water use and improve agricultural productivity. ISFM strategies center on the combined use of mineral fertilizers and locally available soil amendments (such as lime and phosphate rock) and organic matter (crop residues, compost and green manure) to replenish lost soil nutrients. This improves both soil quality and the efficiency of fertilizers and other agro-inputs. In addition, ISFM promotes improved germplasm, agroforestry and the use of crop rotation and/or intercropping with legumes (a crop which also improves soil fertility).
Farmers who have adopted ISFM technologies have more than doubled their agricultural productivity and increased their farm-level incomes by 20 to 50 percent. The value-cost ratios of adopted ISFM options are well above two.