The mineralized and volatilized nitrogen derived from vinasse labelled with 15N were determined in a laboratory experiment, using samples of two soils [a sandy Red-Yellow Podzolic - PV and a clayey Latosol - LR (Oxisol)], collected in Piracicaba, SP, Brazil. The experiment consisted of four treatments: application of vinasse (V*); vinasse with urea (V*+U); vinasse with sugarcane straw (V*+P); and vinasse with urea and sugarcane straw (V*+U+P). Vinasse, labelled with 15N (V*) was applied at a rate of 100 mg.kg-1 of N-vinasse. All treatments, were incubated for 7, 14, 21, 28, and 35 days. N-urea and sugarcane straw were incorporated in the soil at rates of 220 mg.kg-1 and 22 g.kg-1, respectively. NH4+-N and NO3--N concentrations, as a result of the vinasse addition, were affected by soil type. A larger availability of NH4+-N and NO3--N derived from vinasse were observed, when urea was added. Sugarcane straw plus vinasse did not alter the concentrations of NH4+-N and NO3--N derived from vinasse. Urea plus sugarcane straw did not affect NH4+-N concentrations, and affected the NO3--N concentration in LR soil over time. Losses of vinasse-N, due to volatilization, increased with time for all treatments, and were larger for PV (14%) than for LR (5%); but such losses were similar in LR soil.
vinasse-15N; urea; N mineralization; N volatilization