Investigation the Effect of Nitrogen Fertilizer on Maize Yield Parameters (single cross hybrid 704) for AquaCrop Model

Water and nitrogen are two main factors of plant production. Water scarcity is one of the most important challenges in the production of agricultural products in arid and semi-arid regions, as in most parts of Iran. A great deal of research has been done on the interaction between water and nitrogen and has shown that irrigation and nitrogen treatments interact with the yield. So far, various models have been developed to simulate plant performance in response to different levels of water and nitrogen. The FAO organization has provided the AquaCrop model. This model simulates yield performance in response to water consumption. The effect of nitrogen deficiency on yield in the latest versions of the AquaCrop model (versions 4 and 5) is carried out using semi-quantitative method. In this method, nitrogen deficiency is assumed to be based on four parameters: 1- Normalized water productivity (WP*), 2- maximum canopy cover (CCx), 3- The Canopy growth coefficient (CGC) and 4- Canopy decline coefficient (CDC). The hypothesis of this research is that there is a relationship between the four above parameters and nitrogen fertilizer for corn, and from them, we can determine the values of four parameters for each fertilizer level and use them in the AquaCrop model. Therefore, the first goal of this study was to determine the equations between nitrogen fertilizer and the four above parameters. The second goal of this study was to evaluate the accuracy of the AquaCrop model for simulating the response of corn to nitrogen fertilizer using parameters derived from the equations defined in the first part.