Summary
This study provides quantitative characterisation of sheep urination patterns and urine nitrogen chemistry across contrasting pasture types and seasons, based on 193 recorded urination events from six sheep. The findings reveal that whilst sheep on improved pasture excreted higher daily nitrogen loads, this did not translate to greater nitrogen patch loading due to differences in urine spread patterns across soil surfaces. The research provides empirical data and an updated artificial urine formulation to improve accuracy in experimental and modelling assessments of nitrogen losses from sheep grazing.
UK applicability
The findings are directly applicable to UK grassland management and nitrogen loss quantification, as they characterise urine parameters for sheep grazing systems typical of the United Kingdom. The site-specific and seasonal variability observed suggests that UK models assessing diffuse nitrogen pollution from sheep grazing should incorporate pastureand season-specific urine chemistry rather than generic values.
Key measures
Urination frequency and volume; daily urine nitrogen excretion (g N sheep⁻¹ d⁻¹); urine nitrogen concentration (g N L⁻¹); urine-to-soil surface area influenced (L m⁻²); chemical composition; metabolomic profile
Outcomes reported
The study quantified urination frequency (8–11 times per day), urine volume (mean 289 mL per event; 2.77 L per sheep per day), and daily nitrogen excretion in sheep grazing improved versus semi-improved pastures. Chemical composition and metabolomic profiles of sheep urine were characterised seasonally and by pasture type, with provision of an updated artificial sheep urine recipe for experimental use.
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