In a study of the effects of various kinds and amounts of limestone on the chemical and bacteriological properties of certain southern Iowa soils, it was found by the authors (14) that the Grundy silt loam has a rather high absorptive capacity for lime and other basic materials. Although the lime requirement of this soil was approximately 3 tons of limestone per acre, the experiments indicated that considerably more than 3 tons of limestone were necessary to bring the pH to 7.0 or to completely saturate the exchange complex with bases. Quarry-run limestone applied in sufficient amounts to meet the lime requirement increased the pH from 5.19 to only 5.80 in 3 months' time, whereas, three times that amount increased the pH to only 6.6. It was estimated by extrapolation that approximately 12.6 tons of limestone would be required to bring the reaction of this soil up to pH 7.0. Similarly, limestone sufficient to meet the lime requirement increased the degree of saturation of the base exchange complex with bases from 60.13 to 71.16 percent in 3 months, and three times that amount of limestone, or 9.87 tons per acre of the quarry-run material, increased the degree of saturation to only 82.9 percent.