Limestone Dissolution Under Varying Rates and Soil Textures

The agricultural frontier in Brazil advances mainly in areas of sandy soils, where the management of soil fertility is still a challenge, including the practice of liming. Limestone dissolution was investigated under varying doses (0-40 t ha(-1)) in soil samples with a wide range of textural gradients (5%-74% clay). In view of textural variations and limestone rates, the objective was to generate information regarding pH, the residual liming effect, and exchangeable calcium (Ca) and magnesium (Mg) levels, including under overliming conditions. Throughout the textural gradient, the pH was between 4.2 and 8.5. On more sandy soils (5%-18% clay), overheating (pH > 7) was obtained with similar to 2 t ha(-1) of limestone. On clayey soils (37%-74% clay), a similar effect was obtained with similar to 10 t ha(-1) of limestone, indicating the marked difference in the acid buffering capacity of these soils. In addition, the equilibrium pH in the context of overliming in sandy soil was higher (8.2) compared with clayey soils (7.8). The residual liming effect was greater in sandy soils due to the lower potential acidity. Regardless of the soil texture, the Ca/Mg ratio increased in the context of overliming. Liming must be carefully applied and requires proper recommendations, especially on sandy soils, avoiding pH >= 6.5, a condition that is not suitable for most crops.