Nitrous oxide mitigation in UK agriculture

Abstract

Nitrous oxide (N 2 O) makes the single largest contribution to greenhouse gas (GHG) emissions from UK and European Union agriculture. Ambitious government targets for GHG mitigation are leading to the implementation of changes in agricultural management in order to reduce these emissions (mitigation measures). We review the evidence for the contribution of those measures with the greatest mitigation potential which provide an estimated 4.3 t CO 2e ha À1 y À1 GHG reduction in the UK. The mitigation options considered were: using biological fixation to provide nitrogen (N) inputs (clover, Trifolium), reducing N fertilizer, improving land drainage, avoiding N excess, fully accounting for manure/slurry N, species introduction (including legumes), improved timing of mineral fertilizer N application, nitrification inhibitors, improved timing of slurry and manure application, and adopting systems less reliant on inputs. These measures depend mostly on increasing the efficiency of N fertilizer use and improving soil conditions; however, they provide the added benefit of increasing the economic efficiency of farming systems, and can often be viewed as ''win-win'' solutions.

Yield-scaled mitigation of ammonia emission from N fertilization: the Spanish case

“…In the particular case of manure, U, and other N synthetic fertilizers incorporation at seeding, NO 3 − losses can be triggered by leaching during high rainfall seasons or irrigation periods (Quemada et al 2013) and also enhance N 2 O emissions when compared to surface applications (Pain et al 1989). These N losses could be minimized by synchronizing N application rates with crop demand through split applications thus avoiding excess of N (Rees et al 2013). As for mechanical incorporation, washing U could favor the presence of reactive N under conditions of higher soil moisture, due to favorable soil conditions for denitrification processes and subsequent high N 2 O emissions (Wrage et al 2001).…”

Greenhouse gas emissions from the energy crop oilseed rape (Brassica napus); the role of photosynthetically active radiation in diurnal N2O flux variation

“…Despite this lack of understanding of variation in N 2 O emissions, rudimentary management guidelines already exist regarding the timing of fertilizer application (Environment Agency, 2015). These are designed to prevent N losses during rain through leaching and N 2 O emissions but could benefit markedly from a fuller understanding of the processes governing N 2 O fluxes to reduce future emissions (Rees et al, 2013). Currently, IPCC tier 1 emissions factors (EF) guidance states that ca.…”

Nitrous oxide emissions from European agriculture – an analysis of variability and drivers of emissions from field experiments

“…A recent continental study identified N 2 O as the single most important greenhouse gas emitted from landbased sources with emissions from Europe equivalent to 97 Tg C yr −1 (Schulze et al, 2009). Agricultural soils used for grassland and arable production are a major source of N 2 O, and strategies to reduce greenhouse gas emissions from the agricultural sector frequently highlight the importance of management interventions (Mosier et al, 1998;Rees et al, 2013). However, the contribution of management to mitigation can be difficult to assess against a background of fluxes that are highly variable in time and space, since emissions vary significantly in response to both climate and local environmental (particularly soil) conditions (Abdalla et al, 2010;Flechard et al, 2007;Skiba and Ball, 2002).…”