Effect of Different Levels of Irrigation and Nitrogen Fertilizer on Spring Maize Yield in the Presence of Groundwater

One of the most important problems in agriculture is continuous decreasing in quality and quantity of water resources. One of the proposed solutions in the field is deficit irrigation and use of shallow groundwater. This study was conducted to assess the participation share of the shallow groundwater in supplying the water requirement of maize plant. Treatments comprised nitrogen fertilizer (N1, N2 and N3 with values of 450, 375 and 300 kg ha-1, respectively) and irrigation (I1, I2 and I3, with the amounts of 100, 75 and 50% of water requirement, respectively) with a fixed groundwater level at the depth of 70 cm. The results showed that raising the two main treatments levels significantly enhanced the properties of grain yield, dried matter and harvest index. The highest rises in grain yield and dried matter were 6.049 and 15.430 ton ha-1, respectively, which were obtained from the treatment I1. The grain yield was observed 12% increasing with rising nitrogen levels from 300 to 450 kg ha-1. The results showed that the grain yield increased 16% in the presence of water table in comparison with the free drainage conditions. Also, evaluation the results of the groundwater contribution in evapotranspiration showed that the maximum and minimum amounts involved were 31.4 and 5.78%, which were obtained from I3 and I1, respectively. Therefore, using shallow groundwater in spite of reducing the water drainage as well as environmental pollution, causes supplying the part of crop water requirement.