Effects of γ-polyglutamic acid on available nutrients and enzyme activities in gangue-based soil

Purpose his study aimed to explore the effects of polyglutamic acid on the physical-chemical properties and invertase activity of gangue-based soil, clarifying how different addition amounts impact soil indicators and enzyme activities for ecological restoration. Methods ​ Soil samples with varying weathering years were collected from a gangue mountain. A potted experiment involved five polyglutamic acid treatments (0–43.2 g dissolved in 300 mL water). Soil pH, conductivity, nutrient contents, aggregate composition, and enzyme activities (urease, sucrase) were measured, followed by redundancy analysis (RDA). Results ​ Polyglutamic acid rapidly increased soil pH and modified conductivity trends. Its influence on organic matter, nitrogen, phosphorus, and potassium was complex, depending on dosage and time; optimal addition boosted organic matter and nitrogen conversion, promoted potassium availability, and altered water-stable aggregate ratios. Enzyme activities were significantly affected by dosage, with varying initial levels and trends across weathering years; overall, certain enzymes showed increased activity. RDA indicated distinct soil properties under different treatments, with enzyme impacts evolving over time. Conclusions Polyglutamic acid significantly improves gangue-based soil, offering a theoretical basis and technical reference for ecological restoration and soil quality optimization.