© Ricardo-AEA LtdRicardo-AEA in Confidence 1 Guidebook Update - Agriculture chapters Ammonia from fertilisers J Webb on behalf of Ricardo-AEA and Aether and with input from Aarhus University and the EAGER group

© Ricardo-AEA LtdRicardo-AEA in Confidence 2 Task 3.ii: Ammonia emissions from N fertilizer use Earlier work concluded that NH 3 emissions from urea, ranging from 6 to 47% of applied N, are on average greater than those following the application of other types of N fertilizer Earlier editions of the Guidebook indicated that NH 3 emissions following the application of urea were c. 15% of applied urea-N at 12°C The most recent review indicated that emissions following the application of urea may have been significantly underestimated and may be closer to c. 25% of N applied at typical spring temperatures –however, those findings were heavily influenced by the results of a large study carried out in the UK in which emissions of NH 3 were measured using wind tunnels: a technique that can overestimate absolute emissions of NH 3

© Ricardo-AEA LtdRicardo-AEA in Confidence 3 Task 3.ii: Ammonia emissions from fertilizer use Critically review the literature reporting measurements of NH 3 emissions following the application of N fertilizers –using a subset of balanced studies to assess the extent to which they are consistent with the analysis –N fertilizer type –measurement method –temperature –soil type

© Ricardo-AEA LtdRicardo-AEA in Confidence 4 Task 3.ii: Ammonia emissions from N fertilizer use 1. Carry out a multi-factorial analysis of all available measurements of NH 3 emissions following the application of N fertilizers N fertilizer type (Urea; AN; CAN; AS; urea/ammonium nitrate solution (UAN); urea/AS solution (UAS) Application method NH 3 measurement technique Soil pH at the time of N fertilizer application Soil type (soil texture class) Soil clay content (%) Soil cation exchange capacity (CEC) Average temperature during NH 3 measurement period Total rainfall following N fertilizer application Rainfall per day (as duration of experiments differed)

© Ricardo-AEA LtdRicardo-AEA in Confidence 5 StudyMethodUreaANCANASAUNDAP White & R 1990Chamber Lightner et al 1990Field, cl chamb Freney et al 1992Field micromet Sommer Jen 1994Field wind tunn Fox et al 196Field micromet VdWeerd J 1997Field wind tunn Chad et al 2006Field wind tunn Cabrera et al 2008Field micromet Turner et al 2012Field micromet Ni et al 2014Field pass samp Overall unweighted mean Mean for urea compared with other fer Findings from studies which compared NH 3 emissions from > 1 N fertilizer

© Ricardo-AEA LtdRicardo-AEA in Confidence 6 Suggests that wind tunnel overestimation due mainly to fixing wind speed too high Could use wind tunnel data when automatically adjusted to ambient Or perhaps when ambient reported –not usually provided Are we right to always prefer micromet? AuthorsNH 3 emissionWind speed TunnelsMicrometTunnelsMicromet Black et al., 1985 Ryden, Lock =- Mannhein et al * * * Ferm et al 1999 *Adjusted to ambient during experiment

© Ricardo-AEA LtdRicardo-AEA in Confidence 7 Task 3.ii: Ammonia emissions from N fertilizer use Your views are sought on the following key issues: –are there any robust data from your country on NH 3 emissions following N fertilizer application that we should add to the database? –does your national inventory have an approach to calculating NH 3 emissions following N fertilizer application that might be used in the Guidebook? –once the results of the multi-factorial analysis are available we would like your views on the findings and the usefulness of the proposed approach