Coffee residue effect on grain yield and water use efficiency of maize in a maizeharicot bean intercrop in Semiarid Southern Ethiopia 13

A field study was conducted to determine the effect of different rates of coffee residue (0, 3, 6, and 9 Mg ha-1) and (or) N fertilizer (0, 30, 60, and 90 kg ha-1) on soil moisture, soil N, and organic matter (OM), and grain yield and water use efficiency (WUE) of maize in a randomized factorial complete block design with three replicates. Despite moisture stress, coffee residue without and with N fertilizer, raised soil moisture 30-48% and 13-82%, respectively, relative to the control. Fifty-seven per cent of the total variation in soil moisture content was attributed to coffee residue. The residue alone raised N and OM content of the soil (7.6 and 10.0% higher, respectively) relative to the control. Grain yield and WUE of maize were increased by addition of coffee residue and (or) N fertilizer. The presence of coffee residue reversed the adverse effect of moisture stress and raised grain yield and WUE, while these values were low in the unamended control. Coffee residue along with N fertilizer raised soil moisture, and soil N and OM, as well as grain yield and WUE of maize through increased soil organic matter (soil fertility) and soil moisture. Thus, coffee-growing farmers in the region can sustain production and productivity by using coffee residue along with higher rates of N fertilizer.