Leaching of nitrate due to the fertilization with litter of swine bedding, liquid swine manure and chemical fertilizer

摘要

The successive application of high doses of pig manure can lead to contamination by nitrate, due to the high nitrogen concentrations in these wastes, related primarily to the composition of the diet of pigs. This study evaluated changes in levels of N- NO_3 in an Ultisol, in the city of Braco do Norte, SC, during the cycle of culture of maize in a tillage system, in relation to fertilization with litter of swine bedding, liquid swine manure and chemical fertilizer, with application of the appropriatedosage of N and twice the recommended dosage for maize. The evaluations were made at soil depths of 0-15, 15-30, 30-45 and 45-60 cm at six dates during the maize cycle. There were increases in the levels of NO_3 in the soil, with variation of values during the cycle of the culture. The highest value was observed in the treatment fertilized with pig slurry 2x at the depth of 45-60 cm. The results indicate the occurrence of leaching of NO_3, but this nitrate is not yet present at critical levels in the soil.