Recovery of Soil Health and Crop Productivity of Degraded Cultivated Land of Northwest Ethiopian Highlands

Severe soil degradation and fertility depletion have resulted in poor soil health and low crop productivity in the cultivated land of most Ethiopian highlands. Thus, a three-year experiment from 2013 to 2015 was conducted to assess the potential of crop rotation and organic matter application for recovery of the soil health and crop productivity of cultivated land in northwest Ethiopian highlands. Factorial combinations of five crop rotations [bread wheat–clover–potato (R1+); clover–bread wheat undersowing lupine– potato (R2+); potato–clover–bread wheat (R3+); bread wheat undersowing lupine–potato undersowing lupine–bread wheat (R4+); and lupine–potato undersowing lupine–bread wheat (R5+)] and four manure application rates [control without manure (M1); 2.5 t ha-1 sesbania green manure SGM (M2); 5 t ha-1 fresh cattle manure FCM (M3); and 2.5 t ha-1 SGM + 5 t ha-1 FCM (M4)] were laid out in randomized complete block design with four replications at on-station and on-farm testing sites. Interaction of crop rotation and manure application significantly improved the soil properties and crop productivity of the experimental plots. Combined applications of crop rotation and manure in a three-year period resulted in the improvement of crop productivity up to 13 folds, as well as of bulk density, pH, CEC, and contents of organic carbon, total nitrogen, available phosphorous, and exchangeable potassium of the experimental soils up to 25, 20, 67, 92, 154, 96 and 54 percent, respectively, compared to their baseline records. These highest improvements of physicochemical soil properties and crop productivity were mainly recorded from the interaction of R1+ and M4. The results clearly showed that long-term sound crop rotation and organic matter application have a great potential for recovering the soil health and crop productivity of degraded cultivated land in Ethiopian highlands.