NUTRIENTS AND HEAVY METALS IN MAIZE CROP FERTILIZED WITH ROCK PHOSPHATE AND BIOSOLID

Resumo

This study aimed to evaluate effects of natural phosphate and sewage sludge compound fertilization in level of contents of heavy metals and nutrients in two consecutive cultivation of corn grain. The project was conducted in a Haplic Cambisol between April 10, 2009 and September 15, 2010. The treatments in factorial scale 2 x 4 meters corresponds to application on the first corn cultivation of 2 doses of rock Gafsa phosphate (0 and 90 kg ha-1 of P2O5) and 4 compound doses of sewage sludge (0, 25, 50 and 75 t ha-1, in dry specimen). The experiment followed random blocks design with three treatment repetitions. The fertilization with rock phosphate increased the levels of N, P, K and Mg only in the first corn grain cultivation and did not had influence on the levels of Zn, Cu, Ni, Pb, Cr and Cd in the two successive cultivations. The fertilization with sewage sludge compound increased the levels of N, P, K, Mg and Zn in the first corn grain cultivation and P and Zn for the second. In addition, the fertilization with sewage sludge did not had influence on levels of Ca, S, Cu, Ni and Pb in any corn cultivation. Independent of the effect of the treatments, only Pb showed concentration above of acceptable limits for nourishment.