Anna Becvar

Digestates in Farming

Transcript

1. Anna Becvar Consultant, Earthcare Technical (WRAP project)
2. Digestates in farming Anna Becvar Earthcare Technical Ltd. Energy Expo 14th February 2013
3. Digestate available to agriculture Current options:  Whole digestate  Separated liquid  Separated fibre
4. ‘Typical’ nutrient content (kg/tonne fresh weight) Whole ‘food included’ digestate Major Nutrients Total Readily available Potential value £/t Nitrogen (N kg/t) 5.0 4.0 (80%) £3.48 Phosphate (P 2 O 5 kg/t) 0.5 0.25 (50%) £0.17 Potash (K 2 O kg/t) 2.0 1.6 (80%) £0.80 aAssuming N = 87p/kg, P2 O5 = 71p/kg, K2 O = 50p/kg (Jan 2013) Worth £4.45/tonne 30t/ha application = £133.50/ha
5. High readily available N >30% total N (NVZs) RAN Organic N Readily available N (RAN) content of food-based Digestate based on 250 kg N/ha 80% Food based digestate 70% Pig slurry Cattle slurry 45% Green compost Green/food compost <3% 5%
6. Critical to understand forms of nitrogen Readily Available N (i.e. Ammonium-N by analysis) is potentially available for rapid crop uptake Organic N is broken down slowly to become available over months or years Crop Available N is the readily available N left for crop uptake after losses are taken into account
7. Organic materials – N supply and losses To water (NH4 -N, P, FIOs etc). Nitrogen gas Plant uptake Volatilisation Nitrification Soil Organic N Nitrate Immobilisation Nitrous oxide gas Ammonia gas Organic N N Ammonium Denitrification Nitrous oxide gas
8. Need to calculate the Crop Available Nitrogen 1. Location – Rainfall 2. Timing of application (spring or autumn) 3. Method of application (e.g. surface, dribble bar, injection) 4. Use MANNER NPK to calculate crop available nitrogen Should use a FACTS Qualified Advisor Also need to comply with:  The CoGAP in England and Wales, PEPFAA in Scotland NVZ rules where applicable
9. MANNER - NPK Digestate www.planet4farmers.co.uk/manner
10. Digestates – NVZs  Liquid and whole digestates are classed as ‘high readily available N manures’ (i.e. > 30% of the total N present as readily available N) and therefore subject to application closed periods.  High RAN digestate cannot be applied prior to legumes  If fibre digestate analysis shows < 30% available N it will not be subject to application closed periods in a NVZ  Livestock manure fraction counts towards Whole Farm Limit (170 kg N/ha)
11. Digestate BSI PAS110 Non-BSI PAS110 is ‘waste’ Standard Permit SR2010No.4 Deployment (England & Wales) PAS110 in Scotland product (Plus SEPA guidance) PAS110 + ADQP in England & Wales a product Paragraph 7 Exemption in Scotland Crop & livestock manure Digestate Apply as for undigested manures/slurries Regulations on digestate use
12. BSI PAS 110 requirements  AD producers must implement HACCP (hazard analysis critical control point) planning to ensure digestate meets minimum standards for microbial pathogens, heavy metals, stability and physical contaminants and is fit for purpose  Digestate requires pasteurisation if made from imported materials  Wastes subject to ABP Regulations must have been treated appropriately prior to/during the AD process and in application
13. The Anaerobic Digestate Quality Protocol (ADQP) England & Wales  The ADQP ensures that certified digestate conforms to an approved standard and is ‘fit for purpose’  Designated markets: agriculture, forestry, soil/field grown horticulture and land restoration  No need for land spreading permits  Sets out criteria for production of digestate products from specific permitted feedstock  Indicates how compliance may be demonstrated
14. Defra/WRAP/Zero Waste Scotland Digestate and Compost in Agriculture project, 2010-2014 Objectives ‘To quantify the effects of contrasting digestate and compost applications on soil and crop quality, crop available nitrogen supply and emissions to the air and water environments’
15. Field Experiments 2010-2014 Quantifying effects of contrasting digestate and compost applications on soil and crop quality Looking at crop available nitrogen supply GHG Hubs - effects of digestate and compost additions (compared to slurry and FYM) on ammonia (NH 3 ) and Nitrous oxide (N 2 O) emissions, and at Wensum site, leaching losses: nitrate (NO 3 ), soluble P and microbial pathogens WP1 WP2.1 WP2.2
16. Soil Quality Sites – WP1 Site Soils 10/11 11/12 12/13 1 Aberdeen Sandy/light SB WB WOSR 2 Ayr Medium G G G 3 Devizes Chalk LS WW WOSR 4 Faringdon Heavy WW WW WOSR 5 Harper Adams Sandy/light POTS SW SB 6 Lampeter Medium (heavy) G G G 7 Terrington Medium (heavy) WW WOSR WW
17. WP2 – Nitrogen sites  12 sites = crop available N supply from range of digestates (compared to slurry)  3 of 12 sites = effects of digestate and compost additions (compared to slurry and FYM) on ammonia and nitrous oxide emissions, and leaching losses (nitrate, soluble P and microbial pathogens) at Wensum site
18. Site Soils 10/11 11/12 12/13 1 Aberdeen Sandy/light - - SB 2 Ayr Medium G - - 3 Brawdy Medium WW - - 4 East Malling Medium - - WB 5 Gleadthorpe Sandy/light POTS - 6 Harper Adams Medium - - WOSR 7 Loddington Heavy WW - - 8 Newcastle Medium - - G 12 Wessex Chalk - - WW Digestate N response sites
19. WP2.2 Nitrogen Hubs Site Soils 10/11 11/12 12/13 8 North Wyke Heavy - G - 10 Pwllpeiran Medium (heavy) - G - 11 Wensum Sandy/light - WB - Quantify NH 3 and N 2 O emissions to air, and leaching losses to water. Contribute to the development of a more robust and transparent “Inventory of GHG Emissions from UK Agriculture” – linked to Defra project AC0116.
20. Calculating digestate fertiliser replacement values (example 250 kg N/ha application) 0 Nitrogen fertiliser applied (kg/ha) Crop yield (t/ha) 0 1 2 3 4 5 6 7 8 9 50 100 150 200 250 Crop yield = 7.8 t/ha Fertiliser N replacement value = 125kg/ha N N use efficiency = 50% (i.e. 125/250)
21. Wensum: N use efficiency – winter wheat 2012 (% of total N applied) bandspread 0 10 20 30 40 50 60 70 80 90 Autumn Spring Autumn Spring Autumn Spring Food-based digestate Manure-based digestate Pig slurry Organic material Organic material N efficiency (% total N applied)
22. Pwllpeiran: N use efficiency – first cut silage 2012 (% of total N applied) bandspread N offtake method 0 10 20 30 40 50 60 Autumn Spring Autumn Spring Autumn Spring Food-based digestate Manure-based digestate Cattle slurry Organic material Organic material N efficiency (% total N applied) )
23. Ammonia wind tunnels and nitrous oxide boxes at Pwllpeiran
24. North Wyke
25. Ammonia emissions following spring organic material applications to grassland at Pwllpeiran (2 May 2012) 0 10 20 30 40 50 60 70 80 90 100 Surface broadcast Bandspread Surface broadcast Bandspread Food-based digestate Cattle slurry Cattle FYM Green compost Organic material Ammonia-N loss (% total N applied) Green compost Cattle FYM P < 0.001 )
26. Wensum nitrogen hub site
27. Leaching losses at Wensum (light soil) • Teflon water samplers installed at 90cm depth (autumn timings only)
28. Nitrate leaching losses following organic material applications at Wensum (31 August 2011) * Soil incorporation within 24hours * * 0 5 10 15 20 25 Surface broadcast Bandspread Surface broadcast Bandspread Food-based digestate Pig slurry Pig FYM Compost Organic material Nitrate-N leached (% total N applied) Pig FYM Green food compost - winter wheat P < 0.05
29. Good Agricultural Practice when using digestates  Storage – Helps timing and covered stores (required for BSI PAS 110) reduce odour and ammonia loss  Timing - High readily available N means both whole and liquid digestates can only be applied outside application closed periods in NVZs and all digestates should only be applied when there is crop demand  Method – Injection or trailing shoe/hose application equipment will both help minimise odours and conserve N  Spread Risks - Follow a farm Manure Management Plan  Work with neighbours - Tell them what you are doing and spread digestate with an awareness of their concerns/needs
30. Follow the Digestate and Compost in Agriculture project, and download bulletins: www.wrap.org.uk/dc-agri Thank you! anna@earthcaretechnical.co.uk