title: Effects of farm heterogeneity and methods for upscaling on modelled nitrogen losses in agricultural landscapes.
abstract: The aim of this study is to illustrate the importance of farm scale heterogeneity on nitrogen (N) losses in agricultural landscapes. Results are exemplified with a chain of N models calculating farm-N balances and distributing the N-surplus to N-losses (volatilisation, denitrification, leaching) and soil-N accumulation/release in a Danish landscape. Possible non-linearities in upscaling are assessed by comparing average model results based on (i) individual farm level calculations and (ii) averaged inputs at landscape level. Effects of the non-linearities that appear when scaling up from farm to landscape are demonstrated. Especially in relation to ammonia losses the non-linearity between livestock density and N-loss is significant (p > 0.999), with around 20-30% difference compared to a scaling procedure not taking this non-linearity into account. A significant effect of farm type on soil N accumulation (p > 0.95) was also identified and needs to be included when modelling landscape level N-fluxes and greenhouse gas emissions.
authors: Aarhus University, Department of Agroecology, Blichers Allé 20, P.O. Box 50, DK-8830 Tjele, Denmark. tommy.dalgaard@agrsci.dk
authors: T
authors: T
authors: Dalgaard
authors: N
authors: N
authors: Hutchings
authors: U
authors: U
authors: Dragosits
authors: J E
authors: JE
authors: Olesen
authors: C
authors: C
authors: Kjeldsen
authors: J L
authors: JL
authors: Drouet
authors: P
authors: P
authors: Cellier
mesh_terms: D000383:Agriculture / Q000379:methods*; D000393:Air Pollutants / Q000032:analysis; D000641:Ammonia / Q000032:analysis; D000821:Animal Feed / Q000032:analysis; D000822:Animal Husbandry / Q000379:methods; D000818:Animals; D004784:Environmental Monitoring; D005308:Fertilizers / Q000032:analysis; D058751:Livestock / Q000254:growth & development; D008372:Manure / Q000032:analysis; D008954:Models, Biological; D009584:Nitrogen / Q000032:analysis*; D012987:Soil / Q000032:analysis
chemical_list: D000393:Air Pollutants; D005308:Fertilizers; D008372:Manure; D012987:Soil; D000641:Ammonia; D009584:Nitrogen