关中塿土地区土壤pH变化对硒形态及有效性的影响

以关中塿土为研究对象，选择周至-户县中酸性土壤和三原-阎良偏碱性土壤2个典型地区，采集小麦根系土及小麦籽粒样品，测试分析样品中硒含量及土壤中硒的形态，研究土壤pH变化对土壤中Se含量、硒形态、硒的生物有效性的影响，得出以下结论：①关中塿土pH对Se的含量影响不显著，土壤硒形态以强有机结合态、残渣态及腐殖酸结合态为主，大于80%。有效硒（离子交换态硒+水溶态硒）在偏碱性土壤中大于10%，中性土壤为4.91%，弱酸性土壤为8.17%，呈"山谷型"特征。②有效硒中，pH对水溶态Se含量影响不大，对离子交换态硒影响则更为显著。③与青海、宁夏等富硒地区相比，周至-户县、三原-阎良地区塿土中Se含量相对不高，但三原-阎良地区弱碱性、碱性塿土中种植的小麦富硒率分别达89%、100%，表明偏碱性土壤条件下硒的生物有效性较高，其中弱碱性塿土中硒的有效性最高。

Effect of Lou Soil pH Change on Selenium Forms and Availability

Taking Lou soil as the research object, two typical areas of Zhouzhi-Huxian middle-acid soil and Sanyuan-Yanliang alkaline soil were selected. Wheat root soil and wheat grain samples were collected to analyze the selenium content in the sample and the selenium form in the soil. The effects of the change of pH value in soil on the selenium content, selenium form and selenium bioavailability in soil were as follows:(1) The pH had no significant effect on the content of Se in Guanzhong Lou soil, and the soil selenium form was strongly organically combined. The residual state and the humic acid binding state are mainly greater than 80%. The proportion of water-soluble selenium and ion-exchanged selenium is more than 10% in alkaline soil, 4.91% in neutral soil, 8.17% in weakly acidic soil, being "valley type". (2) Effective selenium, pH value is water soluble. The effect of selenium is not significant, and the effect on selenium content in ion exchange state is significant. (3) Compared with Qinghai, Ningxia and other regions rich in selenium,the selenium content of Lou soil in Zhouzhi-Huxian and Sanyuan-Yanliangareas is relatively low. However, the selenium enrichment rate of wheat grown in Sanyuan-Yanliang weakly alkaline and alkaline Lou soil is 89% and 100% respectively, indicating selenium organisms is higher under alkaline soil conditions, especially in weakly alkaline Lou soil.