Optimization of irrigation scheduling and nitrogen rate of maize to improve yield and water use efficiency under irrigated agriculture

A rapid growing of Ethiopian population and rising living standards are increasing the demands for agricultural products especially on food crops. Under this higher pressure over the available water resources of the country are increasing in irrigated agriculture. Higher agricultural productivity means inputs and water should be applied more efficiently. Therefore, understanding water and nitrogen redistribution in the soil profile is important to improve water and nitrogen use efficiency for sustainable agriculture. The aim of the study was to determine the optimal irrigation scheduling and fertilizer rate for better water use efficiency under irrigated agriculture. The effects of irrigation interval on maize yield and other crop properties were also assessed. The experiment was carried in the randomized completed block design experimental design with a combination of five levels of irrigation treatments and three levels of fertilizer rate with three replications of the treatments. The result revealed that the plot received an optimal irrigation interval of 14 days in a combination of 25% more than the recommended fertilizer rate (292.24kg/ha) had significantly higher effects on above-ground biomass (18.25 t /ha) and on grain yield (4.8 t/ha ) of irrigated maize in the study area. However, the maximum water use efficiency of 2.05 kg/m3was obtained at the irrigation interval of 14 days, and the highest level of fertilizer rate. Hence, the use of 14 days of optimal irrigation interval and 25% more fertilizer than the recommended rate is advisable because the grain yield and crop water use efficiency had been improved in the study area. This optimization approaches will be worthwhile in farms with low water availability and input management, high profitability, and high economic capacity,