Abstract
Several experiments were conducted in an effort to modify a new approach to soil testing in which the equilibrating or testing solution contains each element for which the soil is being tested. This report includes results for modification which caused 15 soils to differ more with respect to test levels of Mn, Fe, Zn, Cu, S, and P without substantially changing their rankings for K, Ca, and Mg. Modifications included the incorporation of a preservative, a flocculating agent, a pH buffer, DTPA, and several additional elements to maintain a relatively constant activity coefficient for each element in different soils.Results concluded that the adsorption equilibria soil test can be used successfully to test for several elements. The approach for calculating soil requirements is given for P. Although the test shows promise by indicating soil differences, additional calibration data will be required prior to routine use of the method.