Nitrous Oxide Emissions from Combining Cattle Dung and Urine Patches in a Temperate Grassland

ALVARADO, PARICIA; RICCI, PATRICIA; GONDA, HORACIO LEANDRO; LOMBARDI, BANIRA; BURASCHI, LUCIA; GUZMAN, SERGIO A.; VIDUZZI, GABRIEL; PALLADINO,ALEJANDRO; JULIARENA, M. PAULA

Orlando, FL

Conferencia; 8th International Greenhouse Gas & Animal Agriculture Conference; 2022

Universidad de Florida

Excreta from grazing animals contain large amounts of nutrients, which can result in nitrous oxide (N2O) emissions from small areas on grasslands. Sites where animals congregate are likely to overlap dung with urine patches. The purpose of this study was to investigate the effect of combining cattle dung and urine depositions on N2O emissions in comparison with individual depositions in two different seasons (dry and wet) and to develop local N2O emission factors. Evaluations were performed in Tandil, Argentina, during two separate 98-day trials; a winter-spring (dry) season in 2019 and a summer-autumn season (wet) in 2020. Fresh excreta were applied on the surface of the pasture within circular bases simulating natural cattle deposition which included the following four treatments: dung (2.50 kg), urine (0.75 L), dung+urine (2.50 kg + 0.75 L), and control (without excreta). Nitrous oxide fluxes were measured using the static chamber technique with a total of 21 and 23 sampling occasions in dry and wet seasons, respectively. Daily N2O fluxes revealed a distinct pattern depending on the treatment and time after application. The addition of urine onto dung patches under hot and wet weather conditions had a synergistic effect (threefold increase) on cumulative N2O emissions compared to the sum of the individual N2O emissions from the separate excreta patches (P=0.007). Alternatively, during cold and dry conditions, no differences were found between the N2O emissions from the combined dung+urine and the sum of the individual patches (P=0.35). Thus, preventing the overlap of dung and urine patches under wet conditions can serve as an alternative mitigation strategy for N2O emissions in temperate managed grazed pastures. Moreover, the N2O emission factor mean value, considering the three types of excreta applied, was 0.14 ± 0.08%; and was lower than the mean 0.4% aggregated default emission factor established by IPCC.