Keywords: apparent nitrogen balance, life cycle assessment, LCA, nitrogen budget, nitrogen emissions, farm scale, emission estimation, France, environmental evaluation, environmental pollution, farming, agriculture, environmental sustainability
Evaluation of an operational method for the estimation of emissions of nitrogen compounds for a group of farms
The aim of this article is to evaluate a practical method for estimating nitrogen emissions on the scale of a group of farms, to be used in Life Cycle Assessment (LCA). The method rests on the estimation of nitrogen inputs and outputs to calculate the surplus of the annual nitrogen balance on the scale of a farm. The different gaseous nitrogen losses (NH3, NO, N2O, N3) are then estimated for each livestock or cropping system. The leaching losses in the form of NO3 are assumed to correspond to the surplus of the apparent nitrogen balance to which are added the atmospheric depositions, minus the gaseous losses. The feasibility of this method was studied on 24 farms in the Naizin catchment area (Brittany, France). An analysis of the sensitivity of NO3 estimates to different parameters used to calculate gaseous losses was carried out. Lastly the robustness of the NO3 estimates was examined by comparing them with measurements of NO3 collected within this catchment area.