Abstract

BENNARDI, Daniel Oscar et al. EVALUATION OF THE BUFFER CAPACITY OF ACID SOILS OF THE PAMPAS REGION. Cienc. suelo [online]. 2018, vol.36, n.1, pp.30-38. ISSN 1850-2067.

Soil buffer capacity can be used for quantitative evaluations of the requirement of basic correctors. Hypothesis: The buffering capacity of acid soils of the Pampean region can be estimated by the current pH (1:2.5), potential pH, CEC (Cationic exchange capacity), organic matter (OM) and texture, routine determinations in soil analysis laboratories. The objectives were: i) evaluate the evolution of pH of different acid soils representative of the Pampas Region, with the addition of increasing doses of alkali and acid, and ii) develop functions that allow the estimation of the corrector dose by easy determination edafic properties. Ten soils were selected. Physicochemical evaluations and alkaline and acid titration curves were carried out by the addition of increasing amounts of 0.2 M KOH and HNO₃ 0.2 M, respectively. pH evolution of acid soils tested against alkali and acid aggregation was adjusted by linear regression functions. Both alkaline titration and acid titration curves point to the existence of soils whose buffer capacity could be grouped into two categories. The ones with the best buffer capacity were those of CEC greater than 14 cmol_c kg^-1, OM greater than 30 g kg^-1, clay higher than 200 g kg^-1, silt higher than 310 g kg^-1 and sand smaller than 400 g kg^-1. Routine organic matter and clay content determinations in soil analysis laboratories may be a simple decision-making tool for the dose to be used in liming practice, using multivariate linear regression models, after calibration under field conditions.

Keywords : Liming; organic matter; titration curve; multivariate linear regression.

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