Modelling nitrogen losses from sheep grazing systems with different spatial distributions of excreta

Abstract

The aim of this study was to assess the effect that the randomised versus even distribution of excreta (dung and urine) may have on modelling nitrogen (N) losses by leaching, volatilisation and denitrification from a grazing system. A range of stock densities (from 200 to 2000 sheep/ha, equivalent to an annual stocking rate of 3 to 33 dry sheep equivalent (DSE)/ha respectively) were simulated to represent an increasing application of N excreta to a grazed 1 hectare area either distributed randomly or uniformly. This study found that the proportion of annual N inputs lost by denitrification were significantly lower and leaching N losses were higher at high stocking densities compared to if ex..