Factors Affecting the Lime Requirements of Wisconsin Soils

Soil factors which have been reported to affect lime requirement were measured on 26 Wisconsin Soils, and the importance of these factors in predicting lime requirement was determined by use of linear and multiple regression. The lime requirement was taken as the amount of < 200‐mesh dolomitic limestone necessary to raise the soil pH to 6.5 after 12 months of equilibration. Organic matter (% OM) was found to be significantly related to lime requirement (r = 0.620), and a function of a pH‐organic matter interaction, (pH 6.5 − soil pH) × (% OM) also correlated well (r = 0.884). Clay content, ranging from 5 to 27%, did not appear to be an important factor in determining lime requirement. Exchangeable Al contents were too low in these soils to contribute significantly, and pH 4.8 NH 4 OAc‐extractable Al did not appear to be an important factor. Lime requirement as indicated by the new buffer developed by Shoemaker, McLean, and Pratt was very highly correlated with lime requirement (r = 0.949), while the Woodruff buffer did not correlate as well (r = 0.818).