| To address the issues of low selenium utilization efficiency in selenium-rich soils and crops failing to meet selenium-enrichment standards, this study investigated the optimal combination of four soil amendments to improve selenium availability in selenium-rich regions. Taking the selenium-rich area of Dongerying Town, Jizhou District, Tianjin as an example, four amendments—quicklime, calcium magnesium phosphate fertilizer, composite humic acid, and fermented cattle manure—were applied in a four-factor, three-level orthogonal soil incubation experiment. Range analysis was used to determine the optimal mixing ratio of amendments for enhancing soil selenium availability. The application of composite amendments improved soil physicochemical properties: pH remained stable (6.8~8.2), bulk density decreased, while field water-holding capacity, organic matter, electrical conductivity (EC), and cation exchange capacity (CEC) increased. Soil available selenium content steadily increased over 60 days of incubation, with the most significant improvement observed in Treatment I (38.4% increase). Based on range analysis, the optimal combination is A3B3C2D1 for maximizing selenium availability after 60 days. The study demonstrates that composite amendments can enhance soil physic-chemical properties and increase available selenium content, providing a viable approach for improving selenium utilization efficiency in selenium-rich soils. |
