A Note on the Effect of Soil Reaction and Zinc Concentration on Peanut Tissue Zinc1

Abstract

Zinc uptake by peanuts (Arachis hypogaea L.) is affected by both soil pH and extractable Zn concentration, but the combined effect of these two factors is not well defined. An experiment with lime rates was conducted using NC7 peanuts that showed an exponential decrease in leaf Zn as the soil pH increased from 4.3 to 6.1. The decrease was very rapid when the soil was more acid, and less rapid as acidity decreased. Plant Zn was also shown to increase quadratically with increasing soil Zn with a data set from Georgia. These two relationships were combined, assuming no interaction exists, to be able to predict peanut tissue Zn as a function of both soil pH and extractable Zn with either the Mehlich-1 or Mehlich-3 solutions. Equations are presented that conform closely with currently assumed values of critical deficient and toxic concentrations in the tissue and soil for peanuts. These should be especially helpful in predicting potential toxicities over a range of pH and soil Zn levels.