湖南省耕地土壤硒空间分布及其影响因素

Spatial distribution of selenium in cultivated soil and its influencing factors in Hunan Province

为合理开展富硒(Se)土壤资源利用与富硒农产品开发,进行了湖南省耕地土壤硒含量的空间分布特征及其影响因素等研究。结果表明:湖南省耕地土壤硒平均含量为0.56 mg·kg^(-1),是全国土壤硒元素背景值(0.29 mg·kg^(-1))的1.93倍;湘西南区土壤硒平均含量最高、湘北洞庭湖区平均含量最低;湘西南区变异系数最大,离散程度高,分布不均匀;湘南区变异系数最小,离散程度低,分布相对均匀;全省富硒耕地面积224.96万hm^(2),占耕地面积的60.7%;水田富硒面积为185.63万hm^(2),占全省耕地面积的50.1%;旱地富硒面积为39.33万hm^(2),占全省耕地面积的10.6%。成土母质发育的土壤硒含量大小顺序为:板页岩风化物>石灰岩风化物>第四纪红色黏土>砂岩风化物>花岗岩风化物>河湖冲(沉)积物>紫色砂页岩风化物;不同类型土壤硒含量大小顺序为:黄棕壤>黄壤>红壤>石灰(岩)土>水稻土>潮土>紫色土;当pH<5.0时,土壤硒含量与pH呈负相关;当5.0<pH<7.8时,土壤硒含量与pH呈正相关;当pH>7.8时,土壤硒含量与pH呈负相关;有机质是影响土壤硒含量的重要因素之一,土壤硒含量与有机质含量呈正相关;土壤硒与锌(Zn)、铜(Cu)、锰(Mn)以及阳离子交换量(CEC)呈极显著正相关(P<0.01)。地形因子也是影响土壤硒含量的因素之一,当海拔低于230 m,土壤硒含量随着海拔的升高而升高;当海拔高于230 m,土壤硒含量随着海拔的升高而降低。湖南省耕地富硒土壤面积较大,具有明显的空间差异,需根据区域差异合理保护和开发富硒土壤资源。

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 hm^(2),accounting for 60.7% of the cultivated land area.The area of selenium-rich paddy field was 1.8563 million hm^(2),accounting for 50.1% of the cultivated land area of the province.The area of selenium-enriched dryland was 0.3933 million hm^(2),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.