Carbon Sequestration in European Agricultural Soils by Potential, Uncertainties, Policy Impacts Annette Freibauer Mark D. A. Rounsevell Pete Smith Jan Verhagen UCL

Vleeshouwers & Verhagen, GCB 2002 C fluxes in SOC in the 1 st commitment period: BAU t C ha -1 y -1 Cropland mean flux: (0.40) t C ha -1 y -1 (source) Total in EU-15: 77 (37) Tg C y -1 Grassland mean flux: (0.65) t C ha -1 y -1 (sink?) Total in EU-15: -30 (32) Tg C y -1 Total agricultural soils Total in EU-15: 48 (37) Tg C y -1 (source)

Most promising measures 1 Promote organic input on arable land instead of grassland (crop residues, cover crops, FYM, compost, sewage sludge) 2 Permanent revegetation of arable set-aside land (e.g. afforestation) or extensivation of arable production by introduction of perennial components 3 Biofuel production with short-rotation coppice plantations and perennial grasses on arable set-aside land 4 Promote organic farming 5 Promote permanently shallow water table in farmed peatland 6 Zero tillage / conservation tillage

CroplandGrasslandPeatland Potential per unit area Uncertainty: spatial variability, soil and climate types; no human components

Factors limiting carbon sequestration Sink saturation Non-permanence Availability of land and resources Adoption of measures / contiguous?

Area and resources available total area limitationssuitable area million ha million ha Cropland 73 more organic input organic material ~60? reduced tillage climate, soil 63? extensification, perennials set-aside land 7.3 bioenergy crops set-aside land 7.3 organic farming now 2% of cropland 7 Grassland (in rotation) 8.4 longer duration of leys no need: set-aside 7.3 from leys to permanent grass no need: set-aside 7.3 Peatland in agriculture 3.6 restoration of drained soil highly productive <1-2 Ramsar, CBD! Uncertainty: adoption rate, adoption time?

CroplandGrasslandPeatland Feasible Potential in EU-15 Uncertainty: spatial variability, adoption, permanence of adoption

Environmental effects Tillage AmendmentsExtensif. Peatland Herbizides, pestizides Non-CO2 gases NH3, NOx Biodiversity Water quality Soil quality Sustainable land management Productivity? ? ? ? ?

Farm income Organic amendmentspositive long-term, easy, cheap Bioenergy cropsregion-specific, emerging markets Organic farmingregion-specific, emerging markets Reduced tillageregion-specific, risks, long-term benefits Extensificationregion-specific, compensation payments? Peatland restorationregion-specific, compensation payments? Judgements about farm incomes are always qualified by location – we cannot generalise! different soil types, climates and farm structures A modelling approach to address this problem and to provide better quantification?

Policy impacts Putting C sequestration options into a real-world context influenced by policy Policy effects (post 1990) Other effects Land use change C sequestration potential

Policy changes post 1990 Radical changes in the structure of the CAP driven by the 1992 MacSharry reforms and Agenda 2000 From production-based price support to area payments and set-aside A wealth of rural development and agri- environmental policies

Policy effects on land use Market support (intervention, import duties) that maintain producer prices Production controls - quota: number of dairy cows declining - set aside: C sequestration, biofuels Direct aid payments (arable area, agri- environment) - change in permanent crop production systems - maintenance of meadows in LFA - forestation of agricultural land

Conclusions (1) Policy changes post 1990 have probably had an overall +ve effect on C sequestration But, uncertainties surround the effects of some policies (LFAs, NVZs, organic) and their impacts on farm incomes Policy could contribute further to soil C sequestration in Europe Further research should target policy as well as management options, be geographically explicit and tackle impacts on farm incomes

Conclusions (2): Caveats C balance in grasslands? What measures are best adjusted to regional management preferences? Regional land use / land management history Regional best practice Permanent, contiguous, long-term adoption of measures? Monitoring! Costs? Regional modelling for potential, adoption, income necessary Regional refinement of policy measures necessary

Availability of land and resources / potential Soil carbon sequestration (Mt CO 2 y -1 ) Measure Limiting factor Theoretical Technical Economic? all agric. Given feasible land used limitation by 2012 Cropland Zero-tillage Suitable land = 63 Mha Reduced-tillage Suitable land = 63 Mha < 103 <89.28 <8.93 Set-aside <10% of arable; < 7.3 Mha 103 Max = Perennial grasses and permanent crops No incentives to grow more 165 0? 0? Deep-rooting crops Research and breeding needed for annual crops 165 0? 0? Animal manure Manure avail. = 385 Mt dm y ? Crop residues Surplus straw = 5.3 Mt dm y ? Sewage sludge Sewage sludge = 71 Mt dm y ? Composting Compost available at present = 160 t dm y -1 (8 M ha) ? Improved rotations 0 >0 0? Fertilisation Irrigation Bioenergy cropsonly current set-aside = 7.3 Mha Extensificationcurrent set-aside to extensify 30% of arable agr. = 20 Mha ? Organic farmingCould increase to 10% = 7.3 Mha

Availability of land and resources / potential Soil carbon sequestration (Mt CO 2 y -1 ) Measure Limiting factor Theoretical Technical Economic? all agric. Given feasible land used limitation by 2012 Grassland ?Knowledge! ? ? ? Revegetation Abandoned arable landcurrent set-aside = 7.3 Mha Max Land conversion Arable to woodlandcurrent set-aside = 7.3 Mha Max Arable to grasslandcurrent set-aside = 7.3Mha Grassland toLand-use change since 1990 arablecalculated as 2.7 Mha (since 1990) Future = 0 Permanent crops Land-use change since 1990 to arablecalculated as 0.4 Mha (since 1990) 0 Woodland toNegligible land-use change arablesince 1990 =>

Availability of land and resources / potential Soil carbon sequestration (Mt CO 2 y -1 ) Measure Limiting factor Theoretical Technical Economic? all agric. Given feasible land used limitation by 2012 Farmed organic soils Protection and Assuming all cultivated restorationorganic soils are restored >36 >36 >36 Avoid row crops and tubersNo incentive 0 GHG: 2 0? 0? Avoid deep ploughing No incentive 3 GHG: 3 0? 0? More shallow Possibly attractive on grass- water table land when new melioration is needed = 50 % of grass- 36 GHG: land area = 1.5 Mha Convert arable to grassland No incentive 3 GHG: 3 0? 0? Convert arable Subsidies compensate income to woodlandlosses: adoption rate max. 2 GHG: % of arable area = 0.3 Mha

Non-CAP effects Technological change (plant & animal breeding) World markets & international trade agreements Changing consumer preferences – less meat, shifts from olive to sunflower oil, etc. Opportunity costs of labour, i.e. competition with other sectors Land degradation (e.g. erosion) Irrigation water availability and quality Education and information dissemination