Buffer capacity as a method to estimate the dose of liming in acid soils

Abstract

Objective: The study proposes using the dolomite buffer capacity (BCDolomite) as a method of estimating the lime requirement in soils that agronomically require a pH increase. Design/methodology/approach: In six soil samples with different levels of response to the application of dolomite, the organic matter (OM), the content of sand, silt and clay, pH, K, Ca, Mg and the potential acidity (Al+H) were determined. Assuming an apparent density of 1000 kg/m3 and a volume per hectare of 2000 m3, the soils were placed in polyethylene containers and treated with dolomite in doses equivalent to 0, 750, 1500, 2250 and 3000 kg/ha, establishing the BCDolomite as the inverse of the slope resulting from the relationship between the pH and the dose of dolomite. Results: In soils with low response to the dolomite, the content of clay and OM was 280 and 26 g/kg, respectively, and in high response soils, the content of clay and OM was 240 and 47 g/kg, respectively. In all cases, a simple and direct linear relationship was observed (R2 > 0.85; p < 0.05) in the relationship between pH and dose of dolomite. Limitations on study/implications: The results obtained under controlled conditions show that BCDolomite constitutes a viable method to estimate the lime requirement. Findings/conclusions: The BCDolomite showed sensitivity to the complexity of the clay fraction and to the organic matter in the soil, for which the dolomite requirement is equal to the product of the desired pH increase and the BCDolomite