PERDAS DE FÓSFORO POR LIXIVIAÇÃO EM NEOSSOLO REGOLÍTICO ADUBADO COM ESTERCO BOVINO CURTIDO EM CONDIÇOES SEMIARIDAS

Abstract

Phosphorus (P) is considered to be a soil-immobile nutrient, because P strongly binds to Fe and Al oxyhydroxides. However, it was observed that sandy soils suffer from P. leaching. The objective of this study was to evaluate the loss of P in samples of a Regolitic Neosol fertilized and not fertilized with tanned bovine manure, and to relate the losses of P with Fe and Al forms. Four samples of soil fertilized and not fertilized with bovine manure tanned in the depth of 0 - 10 cm in the municipality of Esperança - PB. After collection, soil fertility analyzes were carried out, including P extracted with Mehlich - 1 and P extracted with water, Fe and Al extracted with ammonium oxalate and dithionite - citrate and bicarbonate. The leaching test was performed by the miscible displacement method using 55.50 cm 3 and 10 cm high acrylic columns filled with soil and a salt solution of KCl and 0.001 M CaCl for leaching. It was observed that in the four samples studied all had P content extracted with Mehlich-1 above 15 mg kg-1. The area A2 had the highest content of Pw (14.45 mg kg -1) and Pext (54.50 mg kg -1), this same area had the loss of Plix (128.83 mg L -1). The correlation between Plix and Fe and Al forms were not all significant. Plix had higher correlation with the more crystalline forms of Fe and Al. The highest loss of P was observed up to 20 NVp this value corresponds to approximately 800 mm of water sheet.