Optimization of Spatial Interpolation and Sampling Size for Soil Zinc Content in Cultivated Land at County Scale Using Cokriging Method
Achievements in the research on the spatial distribution and the suitable sampling size of soil Zn content in cultivated land could lay definite foundation for the evaluation and certification of regions producing agricultural products and for the investigation of land environmental quality.Using organic matters,pH value,total nitrogen,alkali-hydrolyzable nitrogen,available Fe and available Cu and available Mn in the soil and elevation data as auxiliary variables,the accuracy analysis of interpolation was conducted for soil Zn content in the cultivated land in Shulan City of Jilin Province in China,by adopting Cokriging interpolation method.Meanwhile,the applicability of Cokriging method at different sampling sizes was evaluated in the research on the spatial distribution of soil Zn content in the cultivated land at county scale.It was found that at the same sampling size,the root mean square error produced by the Cokriging was lower than that by ordinary Cokriging,with better fitting results.The effects of auxiliary variables on the Cokriging interpolation ranked as total nitrogen＞available Mn＞elevation data＞available Fe＞alkali-hydrolyzable nitrogen＞pH value＞organic matters＞available Cu.Using the elevation data and the available Cu as the auxiliary variables,the soil sampling size was reduced by 20％,and the accuracy on the Cokriging interpolation of soil Zn content was still satisfied.It is concluded that the Cokriging interpolation method as a more accurate and economic spatial interpolation method might provide more information and helps for the research on the spatial distribution of soil heavy metal content in the cultivated land at county scale.
NETL
NSTL
万方数据
维普
