Implications of soil nutrient management practices for greenhouse gas mitigation in Africa

This paper examined in empirical terms the implications of soil nutrient management practices such as crop rotation, improved fallow, residue application and natural fallow on greenhouse gas mitigation in Africa. Using a meta-analysis approach, estimates of soil carbon and organic matter accumulated due to these practices were standardized using different units of reporting soil carbon. The review covered 253 study estimates across African countries using on-line scholarly and scientific databases as well as more general search engines such as Google.. The results show that the mean carbon sequestration through the use of residues, crop rotation, use of improved fallow and natural fallow are 1266, 998, 2413 and 1181 kg C ha(-1) yr(-1) respectively. The amount of carbon sequestered by the use of residues for soil nutrient management was significantly influenced by soil depth (t = 5.14, p < 0.00); soil types (F = 7.28,p < 0.05) and mean annual precipitation (t = 2.67, p < 0.05); while soil depth (t = 3.86, p < 0.05), soil types (F = 3.84, p < 0.05) and mean annual temperature (t = 2.94, p < 0.05) affected soil carbon sequestered through the use of crop rotation. The amount of soil carbon sequestered by natural fallow was associated to soil depth (t = -4.51, p < 0.05), agro-ecological zones (F = 3.10, p < 0.05) and duration of study (F = 5.43, p < 0.05). It is important that these practices be scaled-out to farmers due to the benign effect on the environment.