Estimating cation exchange capacity from agronomic soil tests: Comparing Mehlich?3 and ammonium acetate sum of cations

Soil cation exchange capacity (CEC) measures the capability of soils to hold and release nutrients. It is an important measure for classifying planning nutrient additions, but it not included in routine soil tests offered farmers. In this study, we compared CEC measured with standard laboratory practices (neutral ammonium acetate [AAc]) estimated from agronomic test data (Mehlich-3 AAc). We applied previously published estimation methods a dataset 48 samples. Based on results, traditional underestimate by 36% Mehlich-3 24% AAc. The can be improved including aluminium (12% overestimate) or fitting localized pedotransfer function (3% underestimate), which offers possibility informing land managers about their holding without adding costs analysis.