Water and nitrogen productivity of maize under semiarid environments

Irrigated agriculture is a facing shortage of water and N in semiarid environments where these inputs are limiting factors for crop production. Experiments were conducted to optimize the water and N requirements for maize (Zea mays L.) under semiarid environmental conditions. Crop physiological and agronomics characteristics were evaluated for three irrigation regimes and five N fertilizer levels during 2009 and 2010. The experiments were conducted in a splitplot design by triplicating water regimes in the main plots and N levels in the subplots. Total dry matter production and crop growth rate increased with an increase in the N application rate up to 300 kg ha-¹ for all irrigation regimes. In contrast, maximum grain yield was achieved with application of 250 kg N ha-¹. Polynomial analysis (third order) showed that 275 kg N ha-¹ was optimum for grain yield at normal irrigation. Higher amounts of irrigation and N significantly increased water use efficiency (WUE). Since optimal N rates for maximum grain yield was 250 kg ha-¹ with 525 mm irrigation water ha-¹ during both growing seasons, this may be considered in formulating good agricultural practices for the soil and weather conditions resembling those of this study.