Abstract

OSORIO-MONTOR, Tania Guadalupe et al. Effect of the diet for cattle based on Leucaena leucocephala on the emission of N₂O in a simulated urine patch in a silvopastoral system in the dry season. Rev. Int. Contam. Ambient [online]. 2023, vol.39, 54585.  Epub Feb 12, 2024. ISSN 0188-4999.  https://doi.org/10.20937/rica.54585.

N2O has a global warming potential of 300 times greater than CO2, and in silvopastoral systems, urine is a source of N2O emission. The objective of the research was to evaluate the effect of the diet for bovines based on Leucaena leucocephala on N2O emissions in a simulated urine patch in a silvopastoral system. A Cynodon plectostachyus meadow was used, and 13 samplings were carried out during March - April 2021. The treatments were, A: 20 kg of urea/ha from bovine urine fed with 100% C. plectostachyus hay + 0% L leucocephala, B: 36 kg of urea/ha from the urine of bovines fed with 16% of L. leucocephala + 84% of C. plectostachyus and C: 79 kg of urea/ha from the urine of bovines fed with 33% L. leucocephala + 67% C. plectostachyus. A completely randomized design with four replicates was used. Static closed stainless-steel chambers were used to obtain gas samples at 0, 10, 20 and 30 minutes. Environmental temperature, pH, humidity, nitrate and ammonium contents in the soil were recorded. Data were analyzed with the statistical program SAS 9.0. The N2O emission flux (μg/m2/h) between treatments did not present significant differences. The emission peak was observed on the fourth day of sampling in the treatments (A: 17.49, B: 23.71 and C: 22.88 μg N2O N m2/h). In addition, there was a positive correlation between the N2O flux and soil moisture. The increase in the amount of L. leucocephala in the diet of the animals did not influence the emission of N2O, due to the concentration of urea in the urine. However, a positive correlation with soil moisture was observed.

Keywords : nitrous oxide; climate change; livestock; emissions.