Swine production has great social and economical relevance in Southern Brazil. However, the use of wastes resulted from the production process, as a plant nutrient source may not be sufficient solution to treat pig slurry production. Application of pig slurry to crop fields may result in nitrogen and phosphorus losses, decreasing the plant uptake efficiency and increasing the risk of water contamination. The present work objective is to evaluate the percolation of nitrogen and phosphorus in soil after slurry application. The field work was developed at the Federal University of Santa Maria, from May 2000 to May 2002, in crop rotation using of black oat (Avena strigosa), corn (Zea mays) and oilseed radish (Raphanus sativus) were grown in plots amended with 0, 20, 40, and 80 m³ ha -1 pig slurry, spread onto soil surface before each seeding operation. Increase in nitrate in soil solution increases with the amount of slurry applied, mainly right after application, which coincides with the initial crop development. In spite of that, it was not detected increase on available phosphorus in soil solution. Losses of nitrogen and phosphorus are negligible as compared with the amount applied, although the nitrate concentration in soil solution at the loss peaks was above the recommended levels for water quality.
Manure; crop residue; organic fertilizer; animal waste
