EVALUATION OF 3 CALCIUM EXTRACTANTS FOR COASTAL-PLAIN SOILS

Mehlich 1-Ca is used as an index to predict the Ca requirement for peanut (Arachis hypogaea L.) fruit development in major peanut growing states. Recently, some concern has been raised about the inadequacy of Mehlich 1 extractable Ca for that purpose. Possible use of alternative extractants for soil Ca has been suggested. In this study, relationships among Mehlich 1, 0.2 M NH4Cl and 0.01 M NaNO3extractable Ca were examined in several Coastal Plain soils to which gypsum or lime had been applied. Variability in extractable Ca was much greater following lime treatment than following gypsum treatment. In Bonifay soil, the quantity of Ca extractable by the three extractants was similar in a gypsum treatment, but in a lime treatment (at an application rate equivalent to the gypsum treatment) Mehlich 1-Ca was 2 and 5-fold greater than NH4Cl- and NaNO3-Ca, respectively. © 1990, Taylor & Francis Group, LLC. All rights reserved.