Crop-fertilization interdependence in Ethiopian enset-based systems shapes soil fertility and constrains crop expansion

Most agricultural soils are degraded and limiting crop production. Improved management can increase crop yields and soil health, but trade-offs in the use of resources, such as organic amendments, need to be considered. We sampled 427 fields across agri-systems in the southwest of Ethiopia to investigate the influence of land use and management on soil fertility. Soil samples were collected at a depth of 0–20 cm from homegardens (enset and coffee), annual-crop fields (wheat, faba bean and maize), eucalyptus plots and pastureland. Thirteen soil properties were analyzed, including total carbon, available phosphorus and potassium. We also investigated the fertilization requirements of enset in the region. In general, homegardens had higher soil fertility, while annual-crop fields had lower total carbon than the other land uses. However, homegardens were highly dependent on manure application. Our estimation showed that 20%–32% of the farms have insufficient manure to adequately fertilize their enset plots. With ongoing changes in land use and increasing population pressure in the region, this study suggests that promoting the expansion of intensive systems, such as homegardens, with the aim of improving production, soil fertility and sustainability, is a viable route only if production constraints such as manure availability are also considered.