Interaction of Water and Nitrogen on Yield and Irrigation Water Use Efficiency of Corn (Zea of mays) under Drip-Tape Irrigation Management

Water and nitrogen fertilizer management is essential for increasing water productivity, increasing product production and reducing environmental hazards in modern irrigation systems. The aim of this study was to investigate the interaction of water and nitrogen fertilizer on total biomass (TB) and irrigation water use efficiency (IWUE) of silage maize under drip-tape irrigation system. Four irrigation levels, including two deficit irrigation levels (W1=0.86ETc, W2=0.93ETc), a full irrigation level (W3=ETc), and an over irrigation level (W4=1.06ETc) and three nitrogen fertilizer levels, including no nitrogen fertilizer (N0), 150 kg N ha-1 (N150), and 200 kg N ha-1 (N200) were considered. The twelve experimental treatments arranged in a strip-plot design with complete randomized blocks with three replicates. The studied indices were stem height and diameter and total biomass during growth period. Irrigation management was performed, based on the calculation of corn evapotranspiration by using FAO-Penman Monteith (FPM) equation and soil moisture measurement in the root depth before each irrigation. The result showed that there was a significant effect of irrigation on total biomass and IWUE (P < 0.05). There was a significant effect of nitrogen on TB and WUE (P < 0.01). The minimum TB obtained for W1N0 treatment, 14537 kg/ha, and the maximum TB obtained for W4N200 treatment, 27893 kg/ha. The minimum IWUE for total biomass was 3.09 kg/m3 for W2 level and maximum was 3.57 kg/m3 for W4 level. Overall, TB and IWUE increased with increasing nitrogen. In general, the results showed that drip-tape irrigation system through increasing irrigation efficiency and decrease of soil surface evaporation would save water consumption and increase the water use efficiency and yield production.