فهرست مطالب hamid hatami

Water and nitrogen are known as the two main limiting factors in achieving maximum yield in agriculture. Therefore, the use of nitrogen fertilizer plays a significant role in increasing agricultural production. However, the indiscriminate use of these fertilizers may be due to their low efficiency. Therefore, investigating the challenges of water scarcity and improper nitrogen use management is crucial. In this study, considering the challenges of water scarcity and improper nitrogen use management, an investigation has been conducted.

This experiment was conducted in the research farm of the Agriculture Faculty of Shirvan Azad University during the agricultural year of 1399-1400. The experiment was carried out in the form of strip plots in three replicates and in a complete randomized block design. Three levels of 50%, 75%, and 100% of plant water requirement were considered as the main plot and five levels of zero (N0), 100 (N100), 200 (N200), 300 (N300), and 400 (N400) kilograms of nitrogen per hectare were considered in the subplots.

Most attributes related to yield components had higher values during the second year in comparison with the first year of the experiment. Moreover, plant height, grain weight, rows per cob and kernels per row in the 100% water requirement were greater compared with the 50% water requirement treatment. As a result of 400 kg/ha nitrogen fertilizer application, plant height, rows per cob, kernels per row, 100-grain weight and biological yield increased by 24.4%, 24.6%, 23.8%, 24% and 24.2% compared with the nitrogen-free treatment, respectively.

Increasing nitrogen fertilizer application leads to an improvement in yield and yield components. The only factor that decreased with increased water supply was water use efficiency. Grain yield under 100% water requirement was 38% more than that of 50% water requirement treatment. The difference between 100% and 50% water requirement treatments in terms of the biological yield was 49.5% in the first and 24% in the second year. Also, increased nitrogen fertilizer application led to increased grain yield. However, no significant difference was observed between 300 and 400 kg/ha nitrogen fertilizer treatments, especially in the second year. Therefore, a 300 kg/ha fertilizer application is recommended to achieve a suitable yield. Fertilizer use efficiency was affected by water requirement so that nitrogen use efficiency under 100% water requirement supply at a given nitrogen fertilizer level (e.g. 100 kg/ha) was significantly higher than that of 50% water requirement conditions. Under 100 kg/ha nitrogen application, nitrogen use efficiency in 100% water requirement treatment was 111.5 and in 50% water requirement treatment was 74.3 kg/ha. Thus, nitrogen use efficiency declined by 33% due to decreased water use. Therefore, it can be concluded that in conditions where sufficient water is not available for irrigation, farmers should not use excessive amounts of nitrogen fertilizer because it has little efficiency and only leads to environmental pollution and capital waste.