Metals Availability from Waste and Their Effects in the Soybean Production.

The experiment was conducted from 2002 to 2010, in order to evaluate the concentration of heavy metals from organic waste to the soil, and extracted by DTPA and organic acids. These organic acids are composed of 43% acetic acid, 31% citric acid, lactic acid 21% and 5% oxalic acid. Likewise, it  aimed to verify the occurrence of metal phytotoxicity problems in soybeans, considering the use of urban waste (biodigested sewage sludge, and centrifuged sewage sludge), and industrial (steel slag and lime mud) that were applied over a long period of time. The experiment was carried out in Oxisol, at UNESP farm, at Botucatu, SP, Brazil. It consisted of four types of waste, applied at zero (control), 2.0; 4.0 and 8.0 Mg ha^-1 doses (dry bases), before the soybean sowing,  every two years, totalizing four applications. In the depth analyzed, from 0 to 0.10m and 0.10 to 0.20m, was shown that the LB was the most added metals to soil, extracted by DTPA as well as organic acids. DTPA extracted more Cd, Pb and Zn than organic acids, which further extracted Ni and Cr. However, Cr, Ni and Zn in soybean grain were above the maximum permitted levels for food grains, when received LB, especially at the highest dose applied 8.0 Mg ha^-1. As a result there was a decrease in the height, growth and yield.