Comparison of chemical tests for estimation of the availability of soil zinc

Tests for determining the availability of soil Zn were evaluated by simple and multiple correlation analysis. The soil tests included total Zn, and Zn extractable from soil by 0.2 M MgSO 4 , 0.1 N HCl or dithizone. In simple correlation analyses, each of the tests correlated significantly with the uptake of soil Zn by maize ( Zea mays L.) plants grown in the glasshouse. The predictions were improved significantly with all tests by the inclusion of one or more of the soil variables, pH and clay and organic matter contents, in multiple correlation analyses. The plant uptake of soil Zn could best be predicted from a multiple regression equation which included soil pH and logarithmic functions of 0.1 N HCl‐extractable Zn and soil clay content as the independent variables.