方正县土壤全硒空间变异研究

为了明确富硒水稻主产县方正县土壤中全硒的含量、分布等特征,以方正县农业土壤为研究对象,运用地统计学和Arc GIS相结合的方法研究土壤全硒含量的空间异质性和分布格局,并探讨硒浓度变异与土壤理化性质之间的关系。结果表明,土壤全硒含量变异函数符合指数模型,空间异质性指数Q=0.125,说明全硒含量的变异主要由结构性因素引起,空间自相关性较强。用普通克里格法(OK法)绘制全县的土壤全硒分布图,发现研究区绝大多数土壤(69.3%)属于足硒土壤,硒含量高值区出现在研究区中部及西南部,而低值区主要分布在研究区东北部。不同土壤类型中,泥炭土全硒含量最高(0.267 mg·kg-1),而沼泽土全硒含量最低(0.153 mg·kg-1);不同土地利用方式下,稻田土全硒含量(0.230 mg·kg-1)略高于旱地土(0.217 mg·kg-1)。影响土壤全硒含量的主要因素为土壤有机碳、粘粒及粉粒含量。

The spatial variability of soil total selenium in founder prefecture

Fangzheng county is the main production areas of rice in Heilongjiang Province, which also serves as one of the ma-jor producing counties of the enriched-Selenium ( Se) rice. In this study, the spatial heterogeneity and the distribution of the soil total selenium and the relationship between selenium concentration variability and geochemical attributes were studied using a combination method of geostatistics and ArcGIS in Fangzheng county. The results showed that the variation function of soil to-tal selenium was fit to a exponential model and the spatial heterogeneity index ( Q) was 0. 125, indicating that the variation mainly contributed to the structural factors and there was a strong spatial autocorrelation. The Ordinary Kriging ( OK) was used to map the soil total selenium distribution of the whole county. From the map, it showed that the vast majority of the soils (69. 3%) were sufficient with selenium, and the total soil selenium content was relatively high in the central and the southwest of the study area while low-value areas were mainly located in the northeastern. Among different soil types, peat soil had a rel-atively high Se content (0. 267 mg·kg-1) and bog soil had a relatively low Se content (0. 153 mg·kg-1). Considering the land use, paddy soils had a higher Se content (0. 230 mg·kg-1) than upland soils (0. 217 mg·kg-1). Correlation analy-sis results showed that soil total organic carbon, clay and silt content were the main factors affecting soil selenium content.