Effect of Gypsum Application and Irrigation Intervals on Clay Saline-Sodic Soil Characterization, Rice Water Use Efficiency, Growth, and Yield

Saline-sodic soil is considered as a serious problem which could negatively affect rice water use efficiency, plant growth, and yield. Therefore, the objective of the current study was to investigate the effects of gypsum applied before sowing (i.e. gypsum and without gypsum) and irrigation interval treatments applied after anthesis (irrigation every 4, 6, 8 days) on chemical characterizations of clay saline-sodic soil. In addition, the effect of these treatments on rice growth, water use efficiency and related parameters and yield were investigated. A significant higher efficiency in reclamation of clay saline-sodic soil was obtained in terms of reducing SAR, Na+ and EC when gypsum was applied and water was added every four or six days intervals in comparison to non-treated soil with gypsum and water added every eight days interval. The highest number of spikelets per panicle, ripened grains percent, grain and straw yields were obtained when rice plants were grown on soil treated with gypsum and irrigated every four and/or six days intervals compared to soil with no gypsum and irrigated every eight days interval. The highest water use efficiency was obtained from rice irrigated every six days interval. In conclusion, it may reduce the hazards of the saline-sodic soil due to application of gypsum which improved soil properties, rice growth and its productivity when plants were irrigated every four or six days intervals. This might be due to the valuable nutrient source of gypsum interns of Ca, which mitigated the toxicity caused by salts in saline soils. Gypsum can also be considered as an effective application for clay saline-sodic soil in the North Delta, Egypt.