南方红壤区典型母质发育土壤硒素特征及影响因素

为探究南方红壤区不同母质土壤硒素特征及理化性质对硒有效性的影响，以广西典型红壤区不同母质土壤为研究对象，通过测定硒形态特征及理化性质，并利用AMOS路径分析模型及土壤培养试验，量化了不同因子对不同母质土壤有效硒的影响。结果表明：南方红壤区不同母质土壤总硒含量均高于0.4 mg/kg，其中以花岗岩母质土壤总硒含量最高，以砂页岩母质土壤有效硒含量最高，且变幅最大。土壤硒形态主要以残渣态和有机结合态为主，不同形态硒含量由高到低均表现为：残渣态硒>有机结合态硒>铁锰氧化物结合态硒>交换态硒>可溶态硒。AMOS路径分析模型结果表明，影响不同母质土壤硒形态分配贡献的主要因素是全磷、有机质和pH，第四纪红色黏土母质土壤中的全氮及砂页岩母质土壤中的速效氮的影响也值得关注。利用贡献较大的理化因子开展土壤培养试验，外源理化因子添加后均在一定的时间及剂量条件下出现土壤有效硒含量最大值，且不同母质土壤获得的最佳因子条件不同。因此，不同土壤母质因土壤理化性质的不同，其硒形态特征存在较大差异，不同理化因子作用于土壤后，土壤硒会因土壤环境的变化而重新分配。

Characteristics and Influencing Factors of Selenium (Se) in Red Soils Derived from Typical Parent Materials in Southern China

In order to understand Se characteristics and their influence physicochemical properties of red soils derived from different parent materials in southern China, soil samples were collected from the typical red soils of Guangxi, the contents of total Se, available Se and different Se forms were determined, and their influence factors were explored through the AMOS path analysis model and soil culture experiment. The results showed that soil total Se content was higher than 0.4 mg/kg, which was the highest in red soil derived from granite, while available Se content was the highest and with the largest variation in red soil derived from sand shale. Se was mainly in forms of Se bound to organic matter and residual Se, and the contents of different Se forms from high to low were as follows: residual Se > Se bound to organic matter>Se bound to iron and manganese oxides >exchangeable Se >soluble Se. The results of AMOS path analysis showed soil total phosphorus, organic matter and pH contributed more to the distribution of Se forms. The influences of total nitrogen in red soil derived from quaternary red clays and available nitrogen in red soil derived from sand shale were also noteworthy. Soil culture experiment conducted with the physicochemical factors of greater contribution showed that, after the addition of exogenous physicochemical factors, the maximum soil available Se content appeared at a certain time and concentration conditions, and the optimal factors obtained were different for red soils derived from different parent materials. In conclusion, the differences in physiochemical properties lead to the great differences in the characteristics of Se forms in red soils derived from different parent materials, and the addition of different physiochemical factors result in the redistribution of Se forms due to the changes in soil environment.