Effects of Desulfurized Gypsum Applied Combined with Polyglutamic Acid on Improving Saline Soil

Abstract

[Objective] The effects of desulfurized gypsum and polyglutamic acid (γ-PGA) improves saline soil were studied in order to provide a theoretical and technical basis for improving saline soil in Northwest China. [Methods] Simulated leaching tests in soil columns and simulated growth tests in pots were used to determine the effect of combining desulfurized gypsum with γ-PGA on saline soils from the perspectives of promoting salt leaching, reducing soil salinity, lowering soil pH value, improving soil nutrient status, and promoting crop growth. [Results] The leaching tests showed that combining desulfurized gypsum with γ-PGA could further reduce soil pH value after leaching and increase Na+ leaching; reduce HCO-3 and Cl- contents after leaching, but increase SO2-4, Ca2+, and Mg2+ contents; and effectively reduce the sodium adsorption ratio (SAR) value of the soil. Desulfurized gypsum combined with γ-PGA significantly increased maize height, leaf area, and dry weight, with maximum dry weight at 30 days of growth increasing by 54.40% compared with the control treatment, and by 40.27% and 29.47% compared with desulfurized gypsum and γ-PGA treatments alone, respectively. In addition, soil pH value was lower and soil N, P, and K nutrient contents and soil enzyme activities were higher after the plants were harvested from the combined desulfurized gypsum and γ-PGA treatment. [Conclusion] The application of desulfurized gypsum and γ-PGA can produce complementary and synergistic effects, thereby further promoting soil ion exchange, lowering pH value, increasing soil nutrient content, and promoting crop growth.

Keywords

• salinization
• soil conditioner
• salt leaching
• soil nutrients
• maize