宜章县耕地土壤硒含量空间分布特征及成因

弄清宜章县耕地土壤硒含量及其空间分布和影响因素，对掌握区域内耕地富硒程度、开发特色富硒农产品和保障人体健康具有重大意义。采用网格布点、野外调查采样、分析测定、GS+半方差函数模型、克里金插值研究了宜章县耕地土壤硒含量及其空间分布特征；结合SPSS软件进行相关性分析和方差分析，揭示了土壤硒含量的影响因素。研究结果表明，（1）宜章县耕层土壤硒含量平均值0.64mg/kg，变幅为0.13~2.80mg/kg，变异系数为44.57%，属中等变异程度，耕地土壤富硒面积占比达到97.8%，；（2）土壤硒含量呈聚集性分布，中部有一条自东北向南从玉溪镇经梅田镇、浆水镇、长村乡、一六镇、笆篱镇、天塘乡的中高富硒带，块金效应值为0.505，说明宜章县土壤硒空间自相关性程度为中等，土壤硒含量受空间结构因素（自然因素）和随机因素（人为因素）共同影响；（3）不同成土母质发育的土壤硒含量差异较大，板页岩发育的耕地土壤硒含量最高，平均硒含量达到0.76mg/kg；（4）不同土壤类型对硒含量有明显影响，潮土和黑色石灰土的土壤硒平均含量最高，均达到了0.68mg/kg，紫色土和黄壤硒含量较低，平均硒含量分别只有0.54mg/kg和0.53mg/kg；（5）相关分析表明:土壤硒含量与pH呈显著负相关，与有机质、锰、铜、锌和CEC显著正相关；在富硒农产品开发时，需考虑土壤硒含量分布特征，并结合相应土壤管理、科学施肥、农艺措施等进行。

Spatial Distribution Characteristics and Influencing Factors of Selenium Content in Cultivated Land in Yizhang County

Understanding the spatial distribution and influencing factors of selenium (Se) content in cultivated soil in Yizhang County is of great significance for the development of characteristic Se-rich agricultural products and the protection of human health. The distribution characteristics and influencing factors of Se content in cultivated soil in Yizhang County were analyzed by field investigation, laboratory analysis, mathematical statistics and model simulation. The results showed that: 1)The average Se content of topsoil in Yizhang County is 0.64 mg/kg, ranging from 0.13 to 2.80 mg/kg, and the coefficient of variation is 44.57%, which is a moderate degree of variation. 2)There is a middle-high selenium-rich belt from Yuxi Town to Meitian Town, Jiangshui Town, Changcun Township, Yiliu Town, Fence Town and Tiantang Township from northeast to south in the middle. The nugget effect value is 0.505, indicating that the spatial autocorrelation degree of soil Se in Yizhang County is moderate, and soil Se content is affected by spatial structure factors (natural factors) and random factors (human factors). 3)There are significant differences in Se content in soils developed from different soil parent materials. Soil Se content of cultivated land developed from slate shale is the highest, with an average selenium content of 0.76 mg/kg. 4)Different soil types have obvious effects on selenium content, and the average content of Se in fluvo-aquic soil and black calcareous soil is the highest, reaching 0.68 mg/kg, and the average selenium content of purple soil and yellow soil is only 0.54 mg/kg and 0.53 mg/kg, respectively. 5)Correlation analysis showed that soil Se content is significantly negatively correlated with pH and positively correlated with organic matter, Mn, Cu, Zn and CEC. In developing Se-rich agricultural products, the distribution characteristics of soil Se content should be considered, and the corresponding soil management, scientific fertilization and agronomic measures should be combined.