Archive for the category: Reactive nitrogen processes

Groenestein, C.M.¹, Hutchings, N.J.² , Haenel, H.D.³, Amon, B.⁴, Menzi, H.⁵, Mikkelsen, M.H.⁶, Misselbrook, T.H.⁷, van Bruggen, C.⁸, Kupper, T.⁹, Webb, J.¹⁰

¹ Wageningen UR Livestock Research, De Elst 1, 6708 WD Wageningen, www.wageningenur.nl/en/livestockresearch, karin.groenestein@wur.nl

² Dept. of Agroecology, Aarhus University, Research Centre Foulum, 8830 Tjele, Denmark

³ Thünen Institute of Climate-Smart Agriculture (TI-AK), Bundesallee 50,38116 Braunschweig, Germany

⁴ Leibniz Institute for Agricultural Engineering, Max-Eyth-Allee 100, 14469 Potsdam, Germany

⁵ Agroscope, Inst. For Livestock Sciences, P.O. Box 64, CH-1725 Posieux, Switzerland

⁶ Dept. of Environmental Science, Frederiksborgvej 399, 4000 Roskilde, Denmark

⁷ Sustainable Soils and Grassland Systems, Rothamsted Research, North Wyke, Devon, UK, EX20 2SB

⁸ Organisation, address, city, state, postcode, website, Email

⁹ Bern University of Applied Sciences, School of Agricultural, Forest and Food Sciences Laenggasse 85 CH-3052 Zollikofen

¹⁰ Ricardo Ltd, Gemini Building, Harwell, UK. OX11

Abstract

Ammonia (NH₃) emissions from livestock production systems can be substantial but difficult to measure. Here we explore the relationship between NH₃ emissions, the emission intensity (NH₃-N emitted/product N) and the more easily measured feed Nitrogen Use Efficiency (NUE). Using a conceptual model, we find that the relationship between emission intensity and NUE is equivalent to that between NH₃-N emission and feed N intake. Furthermore, there is a linear relationship between the two, with a slope that is dependent on characteristics of the animal and its feed, and the manure management system. This is illustrated using data taken from the emission inventories of six European countries, which found a linear relationship, with much variation within a commodity type. Using the same data, we show how the effects of animal and feed characteristics can be separated from those of the manure management system.

Atul K Jain¹, Prasanth Meiyappan¹ and Joanna I House²

¹Department of Atmospheric Sciences, University of Illinois, Urbana, IL 61801, USA

²Department of Geography, Cabot Institute, University of Bristol, Bristol, BS8 1SS, UK

Abstract

We estimate the impacts of nitrogen limitation on the CO₂ emissions from land use and land-use change (LULUC), including wood harvest, for the period 1900-2100. We use a land-surface model that includes a fully coupled carbon and nitrogen cycle, and accounts for forest regrowth processes following agricultural abandonment and wood harvest. Future projections are based on the four Representation Concentration Pathways used in the IPCC Fifth Assessment Report. Results show that excluding nitrogen limitation will underestimate global LULUC emissions by 34-52 PgC (20-30%) during the 20th century and by 128-187 PgC (90-150%) during the 21st century. The underestimation increases with time because: (1) Projected annual wood harvest rates from forests summed over the 21st century are 380-1080% higher compared to those of the 20th century, resulting in more regrowing secondary forests, (2) Nitrogen limitation reduces the CO₂ fertilization effect on net primary production of regrowing secondary forests following wood harvest and agricultural abandonment, and (3) Nitrogen limitation effect is aggravated by the gradual loss of soil nitrogen from LULUC disturbance. Our study implies that: (1) Nitrogen limitation of CO₂ uptake is substantial and sensitive to nitrogen inputs, (2) If LULUC emissions are larger than previously estimated in studies without nitrogen limitation, then meeting the same climate mitigation target would require an equivalent additional reduction of fossil fuel emissions, and (3) The effectiveness of land-based mitigation strategies will critically depend on the interactions between nutrient limitations and secondary forests resulting from LULUC.