Dinámica abiótica del fósforo en suelos de Tucumán. Liberación y retención de fosfato

Abstract

The dissolution-precipitation and adsorption-desorption processes on phosphorus (P) released to the soil solution of the Chacopampeana Plain (LLCH), Flat Plain (LLD), and Piedmont (PD) regions in Tucuman, Argentina, was assessed. For that, four surface horizon samples from each region were analyzed. Total P (PTOT), organic P (PORG), and inorganic P forms were determined. Freundlich equation parameters and P release potential (PLF) were determined from the equilibrium data of an absorption experiment performed in isothermal and abiotic conditions. From the Freundlich parameters the relative adsorption capacity (A), surface affinity (1/b), native adsorbed P (Qo) and buffer capacity of P (CBF) were defined. PTOT and the sum of inorganic forms (PINORG) were greater in LLD, and PD than in LLCH (p = 0.01); mean values of A and CBF were greater in PD than in LLCH and LLD (p = 0.01), while PLF mean was higher in LLD than in the other two regions at the same level of significance. A, 1/b, and CBF variations were associated with the exchangeable base saturation (V%), exchangeable Ca (Cai%), pH-water and pH-KCl. Two regression models of PLF on PINORG and V% or Cai% that explained 95% of the observed PLF variations were also adjusted.