The role of integrated soil fertility management in improving crop yields in the Ethiopian Highlands

Land degradation and declining productivity in the Ethiopian Highlands are primarily caused by soil fertility decline due to erosion, nutrient depletion, and soil acidity. An integrated soil fertility management (ISFM) project operating over a six-year period aimed to combat this and boost yields through participatory demonstrations. Despite high levels of yield variability expected from a farmer-managed observational study over a wide area, results show that crop yields increased with increased use of ISFM. Detailed statistical analysis using multiple linear regression models explained the contribution of individual practices. Use of improved varieties and line-seeding rather than broadcasting were consistently and highly significant. The contribution of inorganic blended fertiliser was less clear, probably due to low soil organic matter and use on acidic soils, although response to nitrogen was highly significant. The contribution of organic fertilisers was less than expected, possibly due to soil disturbance from farmer practices of multiple ploughing. Responses to crop residue management and agroforestry practices were significant on most crops reflecting their importance in improving soil water management, soil organic matter and recycling nutrients. Response to lime application on acid soils was highly significant confirming the importance of correcting acidity. Unexplained differences are attributed to the additive effects of using several ISFM treatments as well as unrecorded beneficial farmer management practices. It can be concluded that ISFM can play an essential role in improving productivity, addressing food insecurity and the challenges of climate change. Further expansion will require advocacy, awareness-raising, field-level extension and involvement of the private sector.