Emiss?o de ?xido nitroso e volatiliza??o de am?nia de urina e fezes bovina em pastagens

• Autor(a) principal: Lessa, Ana Carolina da Rocha
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFRRJ
• Texto Completo: https://tede.ufrrj.br/jspui/handle/jspui/3922
• topic: Gases de efeito estufa; Pecu?ria; Excretas; Din?mica de N.; Greenhouse gases; Livestock; Excreta; N dynamics; Agronomia

Brazil stands about livestock worldwide, with a herd of about 200 million head. The national inventory of greenhouse gases shows that the excreta produced in pasture represents about 40% of total emissions of N2O, quantified from IPCC global data, which may not represent the real impact of the country livestock in the gas emissions. Thus, this study aimed to quantify direct emissions of N2O and N losses through volatilization of NH3 from urine and dung on pasture in Cerrado environment and on Oxisol, in Goi?s State, and on Atlantic forest in an Ultisol, Rio de Janeiro State. The influence of soil and climate variables in this process was also evaluated. The study was conducted in experimental areas at Embrapa Agrobiologia, municipality of Serop?dica - RJ, and Embrapa Arroz e Feij?o, Santo Ant?nio de Goi?s - GO. The areas were divided into 18 plots, with three treatments and six replicates, which consisted of plots with faeces, urine and control. In the rainy season, for the first experiment in Goi?s, a treatment with urea (100 kg ha-1 of N) was included, totalizing 24 plots. One litre of urine and approximately 1.8 kg of fresh faeces were added to the respective treatments, by placing them inside the area enclosed by the metal base of closed static chambers used for N2O sampling. In the area adjacent to each chamber, the same treatments were applied to evaluate NH3 volatilization, soil moisture, mineral nitrogen and temperature. Urine clearly increased soil N2O fluxes especially after the frequent rains in Serop?dica and Santo Antonio de Goi?s. Regardless of location, rainfall and the increased availability of mineral N in urine treatment were key factors for occurrence of high N2O fluxes compared to other treatments. During the monitoring periods, emissions from 3.92 to 1045.55 mg N2O-N m-2 were found for treatments with application of urine, accounting for 0.01% and 2.55% of applied N. Even though the high N content in faeces, they did not result in high N2O emissions, which were between 0.56 and 24.46 mg N2O-N m-2, representing 0% and 0.16% of the applied N. The highest and lowest N2O emissions from the excreta were recorded in Santo Antonio de Goi?s for the rainy season. Ammonia volatilization from urine ranged from 2.56 to 169.91 g NH3-N m-2, representing respectively 6.8% and 50.6% of N from excreta. For the faeces, the amounts ranged from 2.38 to 130.26 g NH3-N m-2, representing respectively 2.6% and 12.7% of the total N from this source. It was concluded that urine and faeces do not contribute similarly to N2O emissions in pastures, the first being the main route of N losses through N2O and NH3 volatilization. In dry periods, excreta on pasture do not increase N2O fluxes, but NH3 volatilization is favoured under these conditions.