Selection of a soil extraction and a multiple regression model to predict plant available manganese

Abstract

The ability of seven extractants to predict Mn uptake by barley and soybeans was compared in the greenhouse. Predictive capacities were substantially improved by inclusion of other variables, particularly soil pH. There was no advantage to extraction of moist soil samples and thus air drying proved to be a suitable sample handling procedure.

Little difference in predictive capacity occurred between the equations based on the seven extractants but the extractants were ranked as DTPA + NaHCO₃ > DTPA + NH₄HCO₃ > H₃PO₄ > hydroquinone > NH₄PO₄ > CH‐COONH₄ > DTPA + CaCl₂. All of the equations developed were useful for soil testing procedures.