Investigation of Nitrogen Losses, Corn Yield and Yield Components Under Different Amounts of Nitrogen Fertilizer and Fertigation Management Via Furrow Irrigation

The present study was conducted in the research field of Seed and Plant Improvement Research Institute to investigate the effect of fertilizer amount in three levels (N1: 100, N2: 80, N3: 60 percent of fertilizer requirement) and two splitting methods (T1: four equal usage including 4-6 leaf stage, 10 leaf stage, reproduction stage and inoculation stage and T2: three equal usage including 4-6 leaf stage, 10 leaf stage and reproduction stage) on corn yield and yield components. The treatments were compared with control which is the common fertilizer usage in the region. Based on the results, the highest grain yield in the first year was obtained in T1N1, T1N3 and control treatments. Grain yield in T2 was less than T1. Nitrogen splitting in T2 compared to T1 reduced the nitrogen content and grain protein content by 12.8% and 13%, respectively. Splitting of nitrogen fertilizer in three stages caused more nitrogen uptake by crop leaves at the end of the growing season; however, this did not increase grain yield and seed quality. Except for the control, no significant changes in soil nitrogen content were observed from surface to depth. The highest percentage of soil nitrogen was observed in the two layers of 0-20 and 20-40 cm in the control. The lowest content of soil nitrogen was observed in in T2N3 treatment with 24.5% (0-20 cm) and 24.5% (20-40 cm) more than control, respectively. The highest and lowest nitrogen losses in runoff were observed in T1N1 (23%) and control (7%), respectively. With the reduction of fertilizer application, runoff losses also decreased; in the T1N2 and T1N3 treatments, this reduction was 9% and 14%, respectively. Overall, T1N2 is recommended as a suitable treatment due to the high grain yield, seed quality and reduction of nitrogen losses.