Water and nitrogen are among the most important crop inputs for optimum production of maize (Zea mays L.). A comprehensive experiment was conducted during 2009 and 2010 under the semiarid conditions of Pakistan to evaluate the effects of water and N applications on the growth and yield of irrigated maize. The objective was to formulate water and N best management practices (BMPs) for the above conditions. Three irrigation regimes (525, 450, and 375 mm ha-1) with 5 N rates (0, 75, 150, 225, and 300 kg ha-1) were tested using a split plot with a randomized complete block design. The results revealed that the irrigation and N treatments significantly affected growth and development of the crop plants. Photosynthesis and transpiration rates were influenced by the applied nutrients. The N application at 225 kg ha-1 resulted in maximum values for photosynthesis (26.90 and 27.63 µmol m-2 s-1 during 2009 and 2010, respectively) and transpiration (5.23 and 5.43 m mol m-2 s-1 during 2009 and 2010, respectively). The highest values for leaf area index (4.93) and grain yield (8.40 t ha-1) were also recorded at this N treatment during both growing seasons. On the other hand, the mean crop growth rate (19.23 g m-2 day-1) and biological yield (16.22 t ha-1) were achieved with the 300 kg N ha-1 treatments in 2009 and 2010. Nitrogen use efficiency (NUE) was optimum at 75 kg N ha-1 during both seasons. The highest water use efficiency (WUE) (16.48 and 18.64 kg ha-1 mm-1 during 2009 and 2010, respectively) was achieved by application of 225 kg N ha-1 with an irrigation water depth of 525 mm during both growing seasons. Water stress at the vegetative stage reduced the grain yield by 12.2%, whereas the same treatment at the grain filling stage reduced the grain yield by 22.6%. In the semiarid environment of Pakistan, the application of water at 525 mm ha-1 with 225 kg N ha-1 gave the optimum production of the irrigated maize tested in this experiment. These crop inputs may be considered as water and N BMPs for this region or for those with similar agricultural and environmental conditions. Agricultural inputs based on these BMPs may result in similar NUE and WUE values.

Water and nitrogen are among the most important crop inputs for optimum production of maize (Zea mays L.). A comprehensive experiment was conducted during 2009 and 2010 under the semiarid conditions of Pakistan to evaluate the effects of water and N applications on the growth and yield of irrigated maize. The objective was to formulate water and N best management practices (BMPs) for the above conditions. Three irrigation regimes (525, 450, and 375 mm ha-1) with 5 N rates (0, 75, 150, 225, and 300 kg ha-1) were tested using a split plot with a randomized complete block design. The results revealed that the irrigation and N treatments significantly affected growth and development of the crop plants. Photosynthesis and transpiration rates were influenced by the applied nutrients. The N application at 225 kg ha-1 resulted in maximum values for photosynthesis (26.90 and 27.63 µmol m-2 s-1 during 2009 and 2010, respectively) and transpiration (5.23 and 5.43 m mol m-2 s-1 during 2009 and 2010, respectively). The highest values for leaf area index (4.93) and grain yield (8.40 t ha-1) were also recorded at this N treatment during both growing seasons. On the other hand, the mean crop growth rate (19.23 g m-2 day-1) and biological yield (16.22 t ha-1) were achieved with the 300 kg N ha-1 treatments in 2009 and 2010. Nitrogen use efficiency (NUE) was optimum at 75 kg N ha-1 during both seasons. The highest water use efficiency (WUE) (16.48 and 18.64 kg ha-1 mm-1 during 2009 and 2010, respectively) was achieved by application of 225 kg N ha-1 with an irrigation water depth of 525 mm during both growing seasons. Water stress at the vegetative stage reduced the grain yield by 12.2%, whereas the same treatment at the grain filling stage reduced the grain yield by 22.6%. In the semiarid environment of Pakistan, the application of water at 525 mm ha-1 with 225 kg N ha-1 gave the optimum production of the irrigated maize tested in this experiment. These crop inputs may be considered as water and N BMPs for this region or for those with similar agricultural and environmental conditions. Agricultural inputs based on these BMPs may result in similar NUE and WUE values.