N2o Emission By Urine and Feces of Beef Cattle in Grasslands of Marandu Grass During the Rainy Season.

This study aimed to quantify N2O emissions by cattle excreta in grasslands of Marandu grass pastures in central Brazil during rainy season. The experiment was conducted at Campus of Jaboticabal of the Universidade Estadual Paulista. The soil is classified as Oxissoils and climate as tropical with dry winter and rainy summer. The evaluation of the N2O emissions was performed using of static chambers and treatments were 1.5 l urine 1.5 kg fresh feces, urine l 0.75 + 0.75 kg of fresh feces and control not receive excreta. Samplings of N2O were made in the morning followed by gas chromatographic determination. The evaluation period was of 114 days and the total emission of the period was obtained by weighted average. The uncertainty was calculated through standard error of the mean. All treatments allowed emissions of N2O and we observed a few samples of N2O consumptions. The total feces output represented by issuing N-N2O adding 5.54% of the total N added and de urine e feces mixed 2.23%. Under of N2O emission factor default proposed by IPCC. The treatments feces, urine and feces mixed and urine emitted of 249.3 (± 18.8), 126.5 (± 45.1), 167.9 (± 17.1) mg N-N2O m-2 respectively, among parentheses the standard error of the mean. Emissions was very high because the rainy events and the fraction lost as N-N2O found in this study were high than the default emission factor of direct N2O by cattle excretion on pasture proposed by the IPCC for the tropics.