School of Environment;
Nanjing Normal University;
Nanjing 210046(China);
State Key Laboratory of Soil and Sustainable Agriculture;
Institute of Soil Science;
Chinese Academy of Sciences;
Nanjing 210008(China);
College o f Environment;
Hohai University;
Nanjing 210098(China);
A Department of Plant and Soil Sciences;
Oklahoma State University;
Stillwater 74078-6028(USA);
extractant concentration; extractant type; extraction time; grey relational coefficient; grey relational entropy; liquid to solid ratio;