Water-Yield Relations and Water Use Efficiency of Maize Under Nitrogen Fertigation for Semiarid Environments: Experiment and Synthesis

Abstract

Abstract We examined the main and interactive effects of nitrogen (N) and deficit irrigation (DI) on the yield response factor ( K y ), water use efficiency (WUE), and irrigation water use efficiency (IWUE) of silage maize from a semiarid region of Iran. Experiments were conducted in 2003 and 2004 that included three N fertigation rates (0, 150, and 200 kg N ha −1 N0, N150, and N200, respectively) and four irrigation levels (0.7, 0.85, 1.0, and 1.13 of soil water depletion, W1, W2, W3, and W4, respectively). The soil water content measurements showed that most of the water was extracted from the top 60 cm of the soil profile. DI increased WUE for all N fertilizer treatments with the maximum value being observed at the W2 level. The average of the IWUE for the two years of the study showed that the lowest IWUE was 1.38 kg m −3 for the N0W1 treatment, while the highest IWUE was 1.8 kg m −3 for the N200W3 treatment. A linear relationship was observed between evapotranspiration and the total biomass for all N fertilizer levels in 2003 and 2004. The minimum K y to water was obtained from the N0 level as 0.64 in 2003 whereas the maximum K y was recorded from the N200 level as 0.95 in 2004. This reveals that higher N rates application would enhance corn yield sensitivity to water stress. Overall, the sensitivity of the silage maize to water stress was affected by different planting date and nitrogen fertilizer levels. We also discuss emergent trends in water and nutrient management in light of the increased need for food security in the face of changing climate and growing populations.