Effects of irrigation and fertilization management on reducing nitrogen losses and increasing corn yield under furrow irrigation

Furrow irrigation is the most widely used method of irrigation in the world. The main objective of this study was to investigate the simultaneous management of water and fertilizer in furrow irrigation on corn yield and nitrogen losses. Large scale field experiments were performed in 16 treatments included 80 furrows with a length of 190 m and longitudinal slope of 0.004. The main factor included planting a row on a ridge of 37.5 cm (So) and two rows on a ridge of 75 cm (SR2), and the sub-factor included two irrigation management and 4 fertilization strategies included 3 fertilizer placement on the furrow and ridge (P1, P2 and P3) and fertigation (F). The results showed in all fertilization nitrate losses in So treatment was more than SR2 treatment. The highest nitrate losses occurred in P1 (fertilizer placement on the furrow bottom) and the lowest in P3 (fertilizer placement on the ridge) fertilization. Optimal irrigation applied increased application efficiency, root water and nitrate uptake and reduced nitrate losses up to 50% in So (P1 fertilization) and 22% in SR2 treatment (P2 fertilization) compared to conventional irrigation. Due to the higher percentage of root water and nitrate uptake in So treatment than SR2 in similar fertilizer treatments, plant height, stem diameter, ear weight and number of seeds on the cob of ear in So treatment were higher than SR2, but the grain yield was more in SR2 treatment due to plant densities. The highest grain yield and water productivity in SR2-OI-P3 treatment (wide ridge- optimal irrigation- ridge fertilization), increased by 44.2% and 67.4%, respectively. This study showed that the simultaneous management of water and fertilizer had a significant effect on the increase of water productivity and yield.