Prediction of Available Soil Zn, Cu, and Mn Using Chemical Extractants
1972
Haq, A. U. | Miller, M. H.
The objective of this study was to evaluate various extractants for predicting available Zn in soils. The amount of Zn extracted from 85 soils by four extractants (EDTA, DTPA, EDDHA, and HCl + H₂SO₄), was related to the Zn concentration in corn (Zea mays L.) grown in the greenhouse for 16 days. The effect of other soil variables was determined by including them in a stepwise multiple regression analysis. EDTA and DTPA extractable Zn were superior to the other two extractants, with r values of 0.607 and 0.603, respectively. Of the soil variables tested soil pH had the greatest effect with an r value of −0.586. The inclusion of pH along with EDTA or DTPA extractable Zn gave R² values of 0.745 and 0.759, respectively. For a given level of extractable Zn, the Zn content of corn increased with decreasing pH. The most significant finding of this study is the effect of pH on the use of EDTA or DTPA as a measure of available Zn. If these extractants are to be used for soils with pH values below 7.0, the pH must be included to obtain a satisfactory measure of available Zn. The concentration of Cu and Mn in the corn was not closely related to the amount extracted by EDTA or DTPA. It was concluded that these extractants were not suitable for measurement of available Cu and Mn in the soils used in this study.
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