Effect of coffee Residue and N fertilizer on grain yield and whater-use efficiency of Maize in Maize-Haricot Bean intercrop in the semi-arid part of Southern Ethiopia.

Moisture shortage and low soil fertility, particularly nitrogen, are major production constraints in the semi-arid part of southern Ethiopia. More than 146,000 tons of coffee byproduct (residue) is produced yearly in the southern region alone. For luck of better means of disposal, it is simply dumped or burned thus bringing about environmental pollution. But coffee residue could be a good source of plant nutrients and its efficient use could enhance improvement in soil organic matter, grain yield and water-use efficiency (WUE). A field study was conducted to determine the effect of different rates of coffee residue (0, 3, 6 and 90 kg ha-1) on soil moisture, soil nitrogen and organic matter, grain yield and water-use efficiency of maize. The treatments were laid out in a factorial arrangement in randomized complete block design with three replicates. Coffee residue with and with cut N fertilizer raise soil moisture ranging from 13 to 82% and 30 to 48%, respectively, relative to the control. Fifty-seven percent of the total variations in soil moisture content were attributed to coffee residue as expressed by the regression model. The residue alone raised total nitrogen and organic matter content of the soil by 7.6 and 10%, respectively, as compared to the control. Coffee residue without fertilizer increased grain yield (91%) and WUE (927%) as compared to the control. Addition of coffee residue and/or N fertilizer accounted for 31% of t he total variations in grain or WUE. N fertilizer alone increased mean soil moisture (11%), grain yield 149%), and water-use efficiency (151%) relative to the control. Coffee residue along with N fertilizer positively influenced soil moisture, soil nitrogen and organic matter, grain and water-use efficiency of maize. Besides, application of coffee reside reversed the adverse effect of moisture shortage. Thus, coffee-growing farmers in the region and other parts of Ethiopia can sustain production and productivity by using coffee residue together with N fertilizer and by doing so reduce environmental hazard.