Interaction of water and nitrogen on the yield and water use efficiency in maize using elasticity theory

Water and nitrogen fertilizer are two main factors of agricultural production and deficiency of each one makes reduction in the yield. Deficit irrigation is one of the ways for water management in arid and semiarid areas, but it is effective on the need of nitrogen. Excessive use of nitrogen will be a waste of capital and environmental pollution. In this study the interaction of water and nitrogen fertilizer on maximum of crop yield and maximum of water productivity in maize was investigated using elasticity analysis theory. The tests in the summer of 1393 in the research farm Pardis Aboureihan located in Pakdasht in the South East was Tehran. Split plot randomized complete block design with four treatments for water and four treatments for nitrogen fertilizer in three replications was used. The maximum yield without deficit irrigation and maximum water use efficiency were calculated using the equations of the theory of elasticity.Results showed that maximum yield of 27467 kg ha-1 and 300 kg N ha-1 achieved with 1011 mm of water and water use efficiency was estimated at 2.75 kg per cubic meter. The maximum water use efficiency of 3.02 kg m-3 was obtained with 87% water deficit and 375 N per hectare.