AUTHOR=Thorman Rachel E. , Nicholson Fiona A. , Topp Cairistiona F. E. , Bell Madeleine J. , Cardenas Laura M. , Chadwick David R. , Cloy Joanna M. , Misselbrook Tom H. , Rees Robert M. , Watson Catherine J. , Williams John R. 

TITLE=Towards Country-Specific Nitrous Oxide Emission Factors for Manures Applied to Arable and Grassland Soils in the UK

JOURNAL=Frontiers in Sustainable Food Systems

VOLUME=4

YEAR=2020

URL=https://www.frontiersin.org/journals/sustainable-food-systems/articles/10.3389/fsufs.2020.00062

DOI=10.3389/fsufs.2020.00062

ISSN=2571-581X

ABSTRACT=<p>Nitrous oxide (N<sub>2</sub>O) emission factors (EFs) were calculated from measurements of emissions from livestock manures applied to UK arable crops and grassland as part of a wider research programme to reduce uncertainty in the UK national agricultural N<sub>2</sub>O inventory and to enhance regional inventory reporting through increased understanding of processes and factors controlling emissions. Field studies were undertaken between 2011 and 2013 at 3 arable and 3 grassland sites in the UK. Nitrous oxide emissions were measured following the autumn and spring application of different manures (pig slurry, cattle slurry, cattle farmyard manure (FYM), pig FYM, poultry layer manure, and broiler litter) at typical rates, using representative manure application and soil incorporation methods. In addition, ammonia emissions and nitrate leaching losses (1 site on a light sandy soil) were measured to calculate indirect N<sub>2</sub>O losses. IPCC comparable, direct N<sub>2</sub>O EFs ranged from −0.05 to 2.30% of total nitrogen applied, with the variability driven by a range of factors including differences in manure composition, application method, incorporation and climatic conditions. When data from the autumn applications were pooled, the mean N<sub>2</sub>O EF from poultry manure (1.52%) was found to be greater (<italic>P</italic> &lt; 0.001) than from FYM (0.37%) and slurry (0.72%), with no difference found (<italic>P</italic> = 0.784) in the EF for bandspread compared with surface broadcast slurry application, and no effect (<italic>P</italic> = 0.328) of the nitrification inhibitor, Dicyandiamide (DCD). For the spring applications, the mean N<sub>2</sub>O EF for bandspread slurry (0.56%) was greater (<italic>P</italic> = 0.028) than from surface broadcast slurry (0.31%), but there were no differences (<italic>P</italic> = 0.212) in the mean N<sub>2</sub>O EFs from poultry manure (0.52%), slurry (0.44%), and FYM (0.22%). The study did confirm, however, that DCD reduced N<sub>2</sub>O emissions from slurries applied in the spring by 45%. EF data from this project have been used in the derivation of robust Tier 2 country specific EFs for inclusion in the UK national agriculture greenhouse gas inventory.</p>