Presenting a Model for Water Engineering (Optimizing and Increasing Consumption Efficiency) in Conditions of Stress and Lack of Water and Nitrogen Fertilizer (Case Study of Soybean Plant)

Soil moisture and amount of fertilizer consumption are among the most important environmental factors determining plant growth and yield. This study was conducted as a split-plot design in randomized complete blocks at three iterations in Hormozgan Province, southern Iran, 2021 and 2022. Irrigation at six levels of no irrigation and supplying 40%, 60%, 80%, 100%, and 120% of water requirement was considered as the main factor, and using nitrogen fertilizer at four levels of 0, 50, 100, 150 and 200 kg/ha was considered as the secondary factor. The interaction effect of irrigation and nitrogen fertilizer on seed yield, number of pods per plant, pod length, plant height, relative leaf water, leaf chlorophyll, stomatal conductance, leaf area index (LAI), water productivity, and grain oil and protein per area was significant at the level of 1%. The interaction effect of irrigation and fertilizer showed that the maximum grain yield was obtained as 3,049 kg/ha in the treatment of supplying 100% water requirement and using 150 kg/ha of nitrogen fertilizer. The maximum seed yield-water productivity (2.28 kg/m³) was observed in the treatment of no irrigation and using 150 kg/ha of nitrogen fertilizer. Increasing irrigation and exceeding plant water requirement as well as high consumption of nitrogen had no upward effect on crop yield. The maximum seed yield was obtained in the full irrigation treatment; indicating exceeding this amount of irrigation could cause water loss and yield reduction. The maximum seed yield was observed in the treatment of supplying 100% water requirement and using 150 kg/ha nitrogen, which is recommended for the study area.