Phosphorus fertilizers are intensively used in Brazil, since the low availability of phosphorus often limits yields in tropical soils. However, these fertilizers can be a entranceway for soil contamination with heavy metals. This study was carried out to investigate heavy metal contamination caused by the application of five different phosphorus fertilizers as well as the metal uptake by corn (Zea mays) plants. The fertilizers simple superphosphate, triple superphosphate, Araxá rock phosphate, Yoorin thermophosphate, and Gafsa rock phosphate were applied at rates of 0, 100, 300, 500 and 800 kg ha-1 P2O5 in two successive corn cycles. The highest Cd and Pb concentrations were found in Gafsa rock phosphate. For the acidulated phosphates, simple superphosphate was the richest in Cd and Pb, while the Pb concentration was highest in Yoorin thermophosphate. Gafsa application induced the highest Pb concentration in corn shoots in the first crop cycle. This fertilizer was also responsible for the highest Cd concentration in plants in the second crop. Citric acid was the most efficient extractant for predicting the available soil Cd contents, whereas DTPA estimated Pb availability best.
heavy metals; inorganic fertilizers; soil contamination
