Effects of farm heterogeneity and methods for upscaling on modelled nitrogen losses in agricultural landscapes |
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Authors: | Dalgaard T Hutchings N Dragosits U Olesen J E Kjeldsen C Drouet J L Cellier P |
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Institution: | aAarhus University, Department of Agroecology, Blichers Allé 20, P.O. Box 50, DK-8830 Tjele, Denmark;bCEH Edinburgh, Bush Estate, Penicuik, Midlothian EH26 0QB, Scotland, UK;cINRA, UMR Environnement et Grandes Cultures, BP 01, 78850 Thiverval-Grignon, France |
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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. |
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Keywords: | Agriculture Greenhouse gas emissions Heterogeneity Landscape Nitrogen losses Upscaling |
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