DIFUSÃO DE FÓSFORO EM SOLOS DE ALAGOAS INFLUENCIADA POR FONTES DO ELEMENTO E PELA UMIDADE

Abstract

The experiment was conducted at the Soil Laboratory of the Center for Agrarian Sciences, Federal University of Alagoas to evaluate the effect of different sources of phosphorus, with different levels of humidity on the diffusive flux of phosphorus in soil samples from the State of Alagoas. Samples of four soils from different locations were used. The P sources used were the KH2PO4, Ca(H2PO4)2 and NH4H2PO4, considering two levels of humidity (40% and 80% of field capacity of soil). The test consisted of a factorial arrangement (4 x 3 x 2), corresponding, respectively, the four soils, three sources of phosphorus and two levels of moisture, with four replications in randomized blocks. As experimental units were used rings of PVC. The dose of phosphorus was 50% of maximum capacity for adsorption of phosphorus. To evaluate the diffusive flux, were used anion-exchange paper (PA). The PA was prepared using a filter paper immersed in solution of FeCl3.6H2O and then transferred to a solution of NH4OH. After dried, the leaves were cut into strips and placed in the soil samples. The estimate of the diffusion was performed by quantification of phosphorus adsorbed to the PA. In general, the diffusive flux increased with the decrease in clay content of soils and the higher water content and the source NH4H2PO4 favored greater diffusion.