Sheep Excreta as Source of Nitrous Oxide in Ryegrass Pasture in Southern Brazil

Abstract

. the highest N 2 O-N fluxes occurred 16 days after application of urine and dung, when the highest soil nitrate content was also recorded and the water-filled pore space exceeded 60 %. the mean ef for urine was 0.25 % of applied N, much higher than that for dung (0.06 %). We found that N 2 o-N emissions for the 90-day winter pasture period were 0.54 kg ha -1 for low grazing intensity and 0.62 kg ha -1 for moderate grazing intensity. Comparison of the two forms of excreta show that urine was the main contributor to N 2 o-N emissions (mean of 36 %), whereas dung was responsible for less than 0.1 % of total soil N 2 o-N emissions.

Emissions of Nitrous Oxide and Methane in a Subtropical Ferralsol Subjected to Nitrogen Fertilization and Sheep Grazing in Integrated Crop-Livestock System

“…In the ungrazed treatment, the emission peak varied from 57 μg m -2 h -1 in the soil without N application (control) to 1,099 and 2,055 μg m -2 h -1 at 75 and 150 kg ha -1 , respectively (Figure 1). The N 2 O emissions data in the control area were in agreement with another work in the south of Brazil, which evaluated N 2 O emissions in an ICL system with sheep, where values ranged from 4 to 53 μg m -2 h -1 (Tomazi et al, 2015). Under continuous grazing, N 2 O emission peaks also occurred after urea application, but at a much lower intensity, and they were similar for the N rates of 75 and 150 kg ha -1 (~350 μg m -2 h -1 , Figure 1).…”