Integrated Soil Fertility and Plant Nutrient Management inTropical Agro-Ecosystems:A Review

The greatest challenge for tropical agriculture is land degradation and reduction in soil fertility for sustainable crop and livestock production.Associated problems include soil erosion,nutrient mining,competition for biomass for multiple uses,limited application of inorganic fertilizers,and limited capacity of farmers to recognize the decline in soil quality and its consequences on productivity.Integrated soil fertility management(ISFM) is an approach to improve crop yields,while preserving sustainable and long-term soil fertility through the combined judicious use of fertilizers,recycled organic resources,responsive crop varieties,and improved agronomic practices,which minimize nutrient losses and improve the nutrient-use efficiency of crops.Soil fertility and nutrient management studies in Ethiopia under on-station and on-farm conditions showed that the combined application of inorganic and organic fertilizers significantly increased crop yields compared to either alone in tropical agro-ecosystems.Yield benefits were more apparent when fertilizer application was accompanied by crop rotation,green manuring,or crop residue management.The combination of manure and NP fertilizer could increase wheat and faba bean grain yields by 50%–100%,whereas crop rotation with grain legumes could increase cereal grain yields by up to 200%.Although organic residues are key inputs for soil fertility management,about 85% of these residues is used for livestock feed and energy;thus,there is a need for increasing crop biomass.The main incentive for farmers to adopt ISFM practices is economic benefits.The success of ISFM also depends on research and development institutions to provide technical support,technology adoption,information dissemination,and creation of market incentives for farmers in tropical agro-ecosystems.

Effects of land management practices and land cover types on soil loss and crop productivity in Ethiopia:A review

Identifying land management practices(LMPs)that enhance on-site sediment management and crop productivity is crucial for the prevention,reduction,and restoration of land degradation and contributing to achieving land degradation neutrality(LDN).We reviewed studies in Ethiopia to assess the effects of LMPs on soil loss(84 studies)and crop productivity(34 studies)relative to control practice.Yield variability on conserved lands was assessed using 12,796 fixed plot data.Effects of LMP on soil loss were 0.5-55 t ha^(−1)y^(−1)compared to control practices yielding 50 to 140 t ha^(−1)y^(−1).More than 55%of soil loss records revealed soil loss less than the tolerable rate(10 t ha^(−1)).Area closure,perennial vegetation cover,agronomic practices,mechanical erosion control practices,annual cropland cover,and drainage groups of practices led to 74.0±18.3%,69.0±24.6%,66.2±30.5%,66.1±18.0%,63.5±20.0%,and 40±11,1%soil loss reduction,respectively.A yield increase of 25.2±15.0%,37.5±28.0%,and 75.4±85.0%was found from drainage,agronomy,and mechanical erosion control practices,respectively.The average yield loss by erosion on fields without appropriate land management practice and on conserved fields was 26.5±26.0%and 25±3.7%,respectively.The findings suggest that practices that entail a continuous presence of soil cover during the rainy season,perennial vegetation,retention of moisture,and barriers for sediment transport were most effective at decreasing soil loss and increasing productivity.This review provides evidence to identify the best LMP practices for wider adoption and inform decision-making on LMP investments towards achieving sustainable solutions to reverse land degradation.