Leaching of the different forms of nitrogen by the application of poultry litter, swine waste, and mineral nitrogen on corn cultures (Zea mays L.)

摘要

Agricultural, livestock management, and industrial activities have the potential to cause high levels of contamination to the soil, surface water, and groundwater as a result of accidental or deliberate discharges of pollutants to the environment. In this study, we evaluated the contamination of groundwater by various forms of leached nitrogen (total N, ammonia, nitrate, and nitrite) arising from the application of poultry litter, swine waste, and mineral nitrogen (urea) to the soil. The study was conducted using a set of drainage lysimeters in the experimental area of UFSM, Frederico Westphalen Campus (RS), Brazil. In this study, the use of swine waste and urea as nitrogen sources shows high leaching of ammonia (N-NH_3~+) and total nitrogen (total N) in drainage water in relation to the nitrogen supplied by poultry litter. Comparing the values of ammonia, nitrite, nitrate, and total nitrogen percolates in the soil with the Maximum Permissible Values allowed by Brazilian law, Res.357/2005--the Brazilian National Environmental Council and Ministry of Health Ordinance 2914/2011, it was observed that all analyzed applications of fertilizers resulted in values that exceeded the maximum allowed waste limits. Therefore, the results obtained in this paper regarding the different sources of nitrogen fertilization used on agricultural soils released potentially toxic concentrations of nitrogenous residues that leached through the soil, creating the potential for serious human and animal health effects, such as methemoglobinemia, as the total nitrogen contents released from each fertilization treatment appeared to percolate through the soil layers and into the groundwater, polluting water sources for both human consumption and agricultural production.