A Comparison of Several Methods of Determining Lime Requirements of Soils

Buffer‐indicated lime requirements of four groups of soils using several buffer methods were related to CaCO 2 incubation‐measured lime requirements through regression analysis. Salt accumulated during the incubation period had marked effect on the amount of lime required to bring the soils to pH 6.5. Results from all buffer methods were highly correlated with incubation‐measured values. Slopes and intercepts of regression lines revealed the marked tendency for the Woodruff buffer to indicate too much at low lime requirement levels and too little at high levels. The Mehlich buffer at pH 8.1 indicated approximately the correct amount for soils of high lime requirement but too much for those at low levels. Peech alterations of the Mehlich and the regular Mehlich method gave the same results. The Shoemaker, McLean, and Pratt method was found to be relatively rapid, accurate, and especially well adapted for soils requiring >4,000 lb of lime per acre, having