Abstract:

To clarify the current status of soil fertility and selenium (Se) content in agricultural lands of Yangjiang City, elucidate their correlation, and establish a multi-dimensional ‘Se-fertility’ quality evaluation system, thereby providing data support and scientific basis for optimizing farmland management and developing Se-rich agriculture in the region. Based on agricultural layout of Yangjiang, 23 representative farmland areas were systematically selected across Jiangcheng District, Yangdong District, Yangxi County, and Yangchun City, with 70 soil samples being collected. Soil physicochemical properties and Se distribution characteristics were analyzed, and a comprehensive soil quality evaluation system integrating soil fertility and Se content was developed. The results showed that the agricultural soils in the study area of Yangjiang City had a relatively high sand content, and the textures were mainly sandy loam and sandy clay loam, which were slightly acidic. Soil fertility was generally characterized by moderate-to-high levels of organic matter, total nitrogen, and available potassium, along with extremely abundant available phosphorus. The total Se content ranged from 0.12 to 1.43 mg/kg (mean: 0.47 mg/kg), while the available Se content ranged from 0.01 to 0.15 mg/kg (mean: 0.047 mg/kg). Se-rich soils accounted for 57.1% of the study area, and soils with medium-to-high Se levels reached 94.3%. Additionally, soil texture and organic matter content significantly influenced total Se, while soil texture, available phosphorus, and pH were the main physicochemical factors affecting available Se. The multi-dimensional ‘Se-fertility’ soil quality index for the study area was 0.299, and individual indicator indices ranked as follows: available phosphorus > total Se / available Se > available potassium > organic matter > total nitrogen. The study area possessed inherent advantages in naturally Se-rich agricultural land resources, providing a solid foundation and potential for developing Se-rich agriculture. To enhance the comprehensive quality of agricultural land in Yangjiang City, it is essential to maintain the existing advantages of Se and available phosphorus content while improving organic matter levels and increasing nitrogen-phosphorus nutrients. Concurrently, addressing soil acidification and optimizing soil texture will effectively regulate Se content and its bioavailability, thereby establishing a fundamental basis for advancing Se-enriched and sustainable agriculture.

Key words: Yangjiang City, soil selenium, soil fertility, ‘Se-fertility’ correlation, integrated soil quality evaluation