Effect of Vermicompost on Soil Fertility and Crop Productivity in the Drylands of Ethiopia

Abstract

The nutrient type and amount contributed from vermicompost varies depending on thesource material, earthworm type used, agro-ecology and farmers’ management. These call forcrop, soil and site specific study. This study, therefore, aimed at determining: (i) the optimalvermicompost application rate/s for wheat and maize production; and (ii) the role ofvermicompost on soil fertility improvements. Field experiments in three agro-climatic zones(highland, midland and lowlands) were established on wheat and maize crops following arandomized complete block design. The treatments were vermicompost (2.5, 5.0, 7.5 and10 t ha−1), conventional compost (10 t ha−1), and recommended rates of Nitrogen and Phosphorus(NP = 100 kg DAP and 50 kg Urea) fertilizers. Our results revealed that the studied soil chemicalproperties, primarily, organic carbon (OC %), N (%) and available P (mg kg−1) increased withincreasing vermicompost rate. The 10 t ha−1 vermicompost treated plots had 157-210%,64-81% and 100-242% higher soil total nitrogen content as compared to the control, 10 t ha−1conventional compost and NP fertilizer treatments, respectively. Application of 10 t ha−1vermicompost also resulted in a 1.5-fold and 43-63% grain yield increment of both testedcrops compared to the control and NP treated plots, respectively. However, the highest netbenefit was obtained from 5 t ha−1 vermicompost for maize (86% increase) and 10 t ha−1 ofvermicompost for wheat (152% increase compared to the control). In conclusion, vermicompostat 5 t ha−1 for maize and 10 t ha−1 for wheat can be recommended to sustainably managefarm productivity.