Potassium quantity-intensity relationships of soils from Rio Grande do Sul

Abstract

The Q/I approach was applied to evaluate the K status of eleven representative soils from Rio Grande do Sul (Brazil). The Q/I parameters, labile K (Kc), solution K (AR^k_o) and potential buffering capacity (BC^k) were correlated respectively with exchangeable K, % K-saturation and cation exchange capacity determined with 1M NH₄Cl. When 0.002M CaCl₂ was used as the equilibration solution some of the Ca displaced exchangeable Al from the very acid soils which resulted in an undesirable displacement of the Q/I curve. As a consequence, the Q/I parameters were not comparable among soils.