Index of phosphorus availability from fertilizer in soils of Misiones, Argentina

Carolina Fernández López1, Sara Vazquez, Humberto C. Dalurzo, Luis A. Morales.

The deficiency of phosphorus (P) in tropical and subtropical soils is a problem of recognized importance, which constitutes one of the most transcendental restrictions for crop production. The present work aimed at determining the availability index of phosphorus fertilizer (F) in Alfisols, Ultisols and Oxisols of Misiones, Argentina, so that it could later be used in simulation models. This index is calculated by estimating the slope of the lineal relation between the labile phosphorus and that added as fertilizer using regression analysis. Three different sites were sampled at 0 - 10 cm depths, and the samples, after conditioning, were incubated at room temperature for 180 days and increasing doses of P were applied. The P content was determined every 30 days. The F averages for the Alfisol, Oxisol and Ultisol were 0.10; 0.19 and 0.30 respectively.

Keywords: phosphorus, fertilizer, tropical soils
1 Universidad Nacional del Nordeste, Facultad de Ciencias Agrarias, Sargento Cabral 2131, 3400 Corrientes, Argentina. E-mail:lam@agr.unne.edu.ar.