Effect of Irrigation Water Level and N-fertilizer Rate on Yield and Water Productivity of Wheat Under Furrow Irrigation at Tibila Irrigation Scheme, Arsi Ethiopia

The response of wheat yield to different levels of irrigation and varying amounts of nitrogen fertilizer was investigated from 2020-2022 GC at Tibila irrigation scheme. Three levels of irrigation (70, 85, and 100% ETc) and three nitrogen rates (46, 69, and 92 kg/ha) were arranged in two factorial combination in Randomized Complete Block Design with three replications. Recently released bread wheat variety king-bird was used as test crop. The experimental field was divided into 27 plots with plot size of 4m x 6m dimension to accommodate five furrows with spacing of 60cm and having 6m length. From the result, it is found that, irrigation and nitrogen levels both had a considerable impact on wheat grain yield. The analysis of variance result revealed that the maximum grain yield (5.88 tha-1) of wheat was recorded at 92 kg/ha nitrogen rate and 100% ETc irrigation level. The minimum grain yield (3.98 tha-1) was obtained from 46 kg/ha nitrogen and 70% ETc irrigation treatment. Similarly, the study revealed that other yield components like plant height, spike length, number of seed per spike, productive tiller number and above ground biomass of wheat increased with the increasing rates of nitrogen fertilizer and irrigation water level. Here, increasing the application rate of nitrogen fertilizer from (46-92) kgh-1 and water level from 70% ETc to full irrigation maximize yields of wheat. On the other hand, reducing water level from 100 to 85% ETc and N-fertilizer rate from 92 to 69 kg/ha was not reduce the yield significantly, rather it have water saving and economic advantage. Moreover the partial budget analysis revealed that an application of 85% ETc and 69 kg/ha nitrogen fertilizer is the best treatment to obtain an optimum yield and maximum benefit cost ratio in the study area. Therefore, application of 85% ETc irrigation and 69 kg/ha nitrogen is recommended for optimum returns of irrigation and nitrogen fertilization of wheat in the area.