关键词: 土壤硒, 空间分布, 成土母质, pH, 有机质, 影响因素

Abstract: To rationally utilize selenium-rich soil resources and develop seleniumrich agricultural products, we investigated the spatial distribution characteristics of selenium content and its influencing factors in cultivated soil in Hunan Province. The results showed that the average content of selenium was 0.56 mg·kg^-1, which was 1.93 times the national background value (0.29 mg·kg^-1). The average content of soil selenium in southwest Hunan was the highest and that in northern Hunan was the lowest. The coefficient of variation of selenium content in southwest Hunan was the largest, with high dispersion and uneven distribution. On the contrary, the coefficient of variation of selenium content in southern Hunan was the smallest, with low dispersion and relatively uniform distribution. The area of selenium-rich cultivated land in Hunan was 2.2496 million hm², accounting for 60.7% of the cultivated land area. The area of selenium-rich paddy field was 1.8563 million hm², accounting for 50.1% of the cultivated land area of the province. The area of selenium-enriched dryland was 0.3933 million hm², accounting for 10.6% of the cultivated land area. The sequence of soil selenium content developed from soil-forming parent material was as follows: weathering materials of shale plate > weathering materials of limestone > Q4 red clay > weathering materials of sandstone > weathering materials of granite > alluvial sediments > weathering materials of purple sandstone. The order of selenium content in different types of soil was yellow-brown soil > yellow soil > red soil > limestone soil > paddy soil > alluvial soil> purple soil. When pH <5.0, there was a negative correlation between soil selenium content and pH. When 5.0 < pH < 7.8, there was a positive correlation between soil selenium content and pH. When pH >7.8, there was a negative correlation between soil selenium content and pH. Organic matter was one of the important factors affecting soil selenium content, with a positive correlation between soil selenium content and organic matter content. Soil selenium content was positively correlated with zinc, copper, and manganese contents, and cation exchange capacity (P<0.01). When the altitude was lower than 230 m, soil selenium content increased with increasing altitude. When the altitude was higher than 230 m, soil selenium content decreased with increasing altitude. The area of selenium-rich soil in cultivated land in Hunan Province was large and had noticeable spatial differences. It is necessary to rationally protect and develop the selenium-rich soil resources according to regional differences.

Key words: soil selenium, spatial distribution, parent material, pH, soil organic matter, influencing factor.