Agriculture and the Greenhouse Gas Platform Adrian Williams, Cranfield University (for the whole team) 23-Feb-2016

Current GHG emissions (end of pipe)

The current UK GHG Inventory Mainly Tier 1 and 2, low specificity to UK conditions E.g. N 2 O EF1 No mitigation measures Very low impacts of practice change apart from lower activity Small differences between countries in the UK Limited capacity to address sectoral emissions N flow model and manure management based on non-UK practices in NH 3 inventory and on farms

Aims of the GHG Platform To develop a revised GHG inventory (2006 IPCC GL) capable of representing variations in soils, farming systems, climate and land use across the UK, and the effects of changing practice. Global Tier 1 EF N 2 O 1% N to Tier 2 UK set Identify, collate and process activity data Derive new EFs from existing work (e.g. MIN-NO, lit.) Mitigation effectiveness Undertake targeted experiments Provide thorough uncertainty analysis and error budgets

Basic form of GHGI, N 2 O from wheat

Enhanced form of GHGI, N 2 O from wheat

Platform Structure

Sources of GHG and NH 3 Direct Manufactured N Grazing returns Manure (+ imports) Arable residues Grassland residues Indirect Ammonia, NOx, nitrate From above Direct Manufactured N Grazing returns Manure (+ imports) Arable residues Grassland residues Indirect Ammonia, NOx, nitrate From above

N 2 O emissions from agriculture in 2011 (total 92 kt N 2 O)

New IPPC-approved histosol map

Grazing N 2 O experiments fill gaps

Soils and N 2 O sites 9 Sites across UK Principal agri-climatic zones Manufactured N –Split Grazing returns –Split –Manure Inhibitors (DCD) Chambers

New EFs: desk based Systematic Literature Review (SRUC)  941 publications gathered  Publications screened for applicability  Result 38 >= 6 Mo.  V few to IPPC standards  Expt. MIN-NO.  Mitigations  Modelling  Synthesis

Secondary N 2 O Ammonia and NOx measured with N 2 O New EF, not conversion factor Leaching: ADAS NitCat model (Lord, 1992) Model for grass, but arable Tier 1 Fraction of leached N IPCC Default 30%

N 2 O EF1 so far Total N input is the most consistent driver of emissions (+ soils, crop, climate) Experimental EFs generally lower that the IPCC default (EF1) Includes manufactured N and excretory returns And inhibitors

Arable sector (1) New approaches Disaggregation of N fertilisation rates BSFP for GB and FBS for NI Region Robust farm type Soils End use Residue management Move from 1996 single values to 2007 approach Question Tier 1 defaults Activity data on management

Arable sector (2) Cultivation methods Inversion, Reduced, Direct drill (minimum) Activity data Affect N 2 O or soil C? Revised EF1 and FRACLeach AC0116 and UK leaching model? Spatial disaggregation JASC (core data) overlaid with soil maps Possible rules to allocate crops and soils End use of crops Regional (multi-national) level E.g. millers determine feed and milling wheat proportions

Wheat: current Current disaggregation

Wheat: current Current disaggregation

Wheat: future Increased country and UK specific data

Wheat: N rates, non-milling Rates down in Wales & NI Assumed all in NI is non-milling

Wheat: N rates, Milling Scotland: National England: RFT

Residues IPPC from constants to R = m Y + c But defaults “US & World” orientated Major omissions: OSR and sugar beet

Data challenge: straw GB or E? MAFF BSFP

N excretion (Nex) from ruminants (Monogastrics stay the same) Current: Tier 1 factors New model –based approach –Regression fits for Nex –Mass balance Production level Animal type Diet (e.g. DMI, CP) Linked by animal systems models Plus split of urine and dung N

Methane from ruminants Current: Tier 2 for dairy cattle Tier 1 other cattle and sheep New model –based approach and new EFs Regression fits for enteric methane Production level Animal type Diet Plus excretion of VS for manure management and subsequent methane Linked by animal systems models

New experimental measurements 4000+

The revised beef sector approach Populations past and future: June to CTS-APHIS Beef cows

Breed type changes over time

Beef age profile: age at death traceable Males Females

Breakdown of breed roles from CTS

Estimated body weights by breed type

Body weights Carcass weights industry and SRUC LW estimated from CW Increase observable in cows: was constant.

Growth curves for cows: basis of MER method Linearise life stages?

Metabolisable energy reqs. for beef cow

MER to Excretion MER + feed composition – Intakes of DM, N, GE DMI → CH 4 (AC0115) N → N Ex → EFs → N 2 O (AC0115-6) – Partition to grazing and manure management About 55% N in urine GE → VS Ex → EFs → CH 4 from manure – Partition to manure management methods

Effects of some changes: cows AC0116

Effects of some changes: finishers

Effects of changes on enteric methane: finishers Ratio of new over current annual methane emissions

Diet and CH 4 : concentrate rate, with DMI based EF. Continental bulls, 12 months slaughter About 3% max effect

Concluding discussion More responsive to changed input data – Numbers down & emissions down – Slaughter age captured automatically CH 4 not changed v much, but up N 2 O changes bigger, but down Small overall change, but right reasons! Challenges: – Feed data – KoP and LW – Tension between research and delivery computing intensity for cattle population data.

Sensitivity analysis for 1990 emissions Uncertainty: sensitivity analysis methane

Some data challenges Activity data uneven over UK – NI FBS good for physical feed data – NI less good for N – FPS in England repeated, SAPM elsewhere – E.g. Manure management – Dietary practices on farms: E * 2 CTS from 2005, but we need 1990 & others Most surveys designed for other purposes or… – CTS – Poultry register – IACS field level: if only

GHG Platform summary Very comprehensive assessment of agricultural GHG sources and mitigation methods Reconciling modelled and experimental results Total N input is the most consistent driver of N 2 O emissions (+ soils, crop, climate) Experimental N 2 O EFs generally lower that the IPCC default (EF1) DMI most important term for enteric methane Responsiveness increased Disaggregation level and new EFs now Building the new inventory now & delivery soon

Anticipated Benefits Respond to changes in practice Changes over time better reflect actual farm activities Better reflection of UK conditions Input data links GHG and NH 3 inventories Reporting By country (5 km grid underlying) By sector To meet UNFCC reporting (Kyoto et al.) UK climate change targets National or sectoral targets within the UK

Thank you and all the partners and funders And so many more