Department for Environment, Food and Rural Affairs Research project final report Project title Assessment of the response of organo-mineral soils to change in management practices Sub-Project ii of Defra Project SP1106: Soil carbon: studies to explore greenhouse gas emissions and mitigation Defra project code SP1106 Contractor SKM Enviros organisations Rothamsted Research / North Wyke CEH Cranfield University ADAS Report authors Roland Bol ([email protected]), Martin Blackwell, Bridget Emmett, Brian Reynolds, Jane Hall Anne Bhogal, Karl Ritz. Project start date October 2010 Sub-project end May 2011 date Contents Title page 1 Executive summary 7 Background to the project 10 Objectives 12 Section 1. Definition of organo-mineral soils in England and Wales 1.1. Rationale 13 1.2 Comparison with other definitions of organo-mineral soils 17 1.3 Organo-mineral soils in an European context 19 Section 2. Distribution of organo-mineral soils in England and Wales 2.1 Methods 22 2.2 Distribution organo-mineral soils in relation to national boundaries 26 2.3 Distribution of organo-mineral soils in relation to Environmental Zone 30 2.4 Distribution of organo-mineral soils in relation to land cover type 31 2.5 Distribution of organo-mineral soils in relation to designated areas 32 2.6 Estimates of C storage in organo-mineral soil (0-15 cm) using CS2007 data 39 Section 3. Ecosystem services provided by organo-mineral soils 3.1 Introduction 42 3.2 Approach 42 3.3 Initial assessment of ecosystem services by land cover on organo-mineral soils 47 3.4 Assessment of ecosystem services of organo-mineral soils by environmental zone 52 3.5 Assessment of ecosystem services of organo-mineral soils by soil type 53 3.6 Impacts of climate change on ecosystem services from organo-mineral soils 55 3.7 Comparison of ecosystem services delivered by organo-mineral soils with organic soils and mineral soils 56 3.8 Concluding remarks and comments 59 Section 4. Best practices for managing carbon in organo-mineral soils 4.1 Introduction 61 4.2 Carbon turnover and storage in soils 61 4.3 Approaches 62 4.4 Best Practices for retaining carbon in organo-mineral soils 64 4.5 Designated areas 76 4.6 Conclusions 76 2 Section 5. Impact of changing land use and management on ecosystem services provided by organo-mineral soils 5.1 Approach 77 5.2 Results 78 5.3 Summary 83 Final conclusion 84 Acknowledgements 84 References 84 Annex 1 92 3 List of Tables Table 1 Definitions of organo-mineral Soils – based on the National Soil Map of England and Wales Table 2 WRB Soil Reference Groups representing organo-mineral soils Table 3 LCM2000 land cover types used in the analysis of organo-mineral soils Table 4 The Environmental Zones used in Countryside Survey Table 5 Areal extent (ha) of organic-soils in England and Wales derived from NSRI data Table 6 Areas of organo-mineral soils in Wales estimated by SP0116 and the ECOSSE project (SEERAD, 2007) Table 7 Area (ha) of each soil category within each Environmental Zone Table 8 Organo-mineral soil-land cover type combinations showing areas (ha), percentage of total area of each soil category in England and percentage of total area of each LCM2000 land cover type in England for those combinations accounting for 10% or more of the total area (shaded grey) Table 9 Organo-mineral soil-land cover type combinations showing: areas (ha); percentage of total area of each soil category in Wales and percentage of total area of each LCM2000 land cover type in Wales for those combinations accounting for 10% or more of the total area (shaded grey) Table 10 Areas of organo-mineral soils in England and Wales included within designated areas Table 11 Estimated soil (0-15 cm) C stocks held in each organo-mineral soil category across England and Wales (E&W) in 2007 and comparison with soil (0-15 cm) stocks for E&W and Great Britain (GB) from Emmett et al . (2010) Table 12 Estimated soil (0-15 cm) C stocks held in organo-mineral soils in England and in Wales in 2007 and comparison with country level and GB soil (0-15 cm) C stocks from Emmett et al . (2010) Table 13 Assessment of ecosystem services delivered by the dominant land cover types occurring on organo-mineral soils in England and Wales Table 14 Dominant (>5% total spatial extent of soil type within each environmental zone) land cover types for three organo-mineral soil types Table 15 Dominant (>5% total spatial extent of environmental zone) land cover types for organo-mineral soils occurring within five environmental zones Table 16 Assessment of ecosystem services of organo-mineral soils in England and Wales by environmental zone Table 17 Assessment of ecosystem services of organo-mineral soils in England and Wales by soil type Table 18 Qualitative comparison of ecosystem services delivered by organic, organo-mineral and mineral soils in England and Wales Table 19 Potential best practices for retaining carbon in organo-mineral soils 4 Table 20 Summary matrix of the relative benefits/disbenefits of best practices for semi-natural grassland Table 21 Summary matrix of the relative benefits/disbenefits of best practices for improved grassland Table 22 Summary matrix of the relative benefits/disbenefits of best practices for cropland Table 23 Summary matrix of the relative benefits/disbenefits of best practices for forestry Table 24 Summary matrix of the relative benefits/disbenefits of best practices for heathland Table 25 Potential impact of changing to ‘best practice for retaining carbon in organo-mineral soils’ on overall ecosystem services for semi-natural grasslands Table 26 Potential impact of changing to ‘best practice for retaining carbon in organo-mineral soils’ on overall ecosystem services for improved grassland Table 27 Potential impact of changing to ‘best practice for retaining carbon in organo-mineral soils’ on overall ecosystem services for cropland Table 28 Potential impact of changing to ‘best practice for retaining carbon in organo-mineral soils’ on overall ecosystem services for forest Table 29 Potential impact of changing to ‘best practice for retaining carbon in organo-mineral soils’ on overall ecosystem services for heathland 5 List of Figures Figure 1 Reference Section for Peat soils Figure 2 Limiting percentages of organic carbon/organic matter and clay for organic and organo-mineral soils. Figure 3 Distribution of Leptosols in Europe Figure 4 Distribution of Umbrisols in Europe Figure 5 Distribution of Podzols in Europe Figure 6 Distribution of Gleysols in Europe Figure 7 Land Cover Map 2000 for England and Wales showing broad groupings of land cover types. Figure 8 Map of the Environmental Zones for England and Wales used in the analysis of organo-mineral soils by land cover type Figure 9 Distribution of organo-mineral soils in England and Wales. Figure 10 Percentage of the total areas of England, Wales and England and Wales covered by organo-mineral soils. Figure 11 Percentage cover of each soil category by Environmental Zone in England and Wales Figure 12 Percentage of the total area of each organo-mineral soil category in England falling within a designated area. Figure 13 Percentage of the total area of each designation in England underlain by organo- mineral soils. Figure 14 Percentage of the total area of each organo-mineral soil category falling within designated areas in Wales. Figure 15 Percentage of the total area of each designation in Wales underlain by organo-mineral soils. Figure 16 Land use capability map of England and Wales with respect to suitability for grazing winter cereals Figure 17 Key elements of the soil carbon budget Figure 18 Distribution of broad land-cover classes associated with organo-mineral soils in England and Wales 6 Assessment of the response of organo-mineral soils to change in management practices Executive summary A generic definition of organo-mineral soils is those soils that have a surface horizon (otherwise referred to as topsoil) relatively rich in organic matter but with less than 40 cm of peaty surface layer, and include rankers, rendzinas, podzolic and gleyed soils. These are further defined to three types of organo-mineral soils: (1) Humose topsoil greater than 15 cm thick; (2) Peaty loam or peaty sand topsoil greater than 15 cm thick; or (3) Peat less than 40cm thick starting at or near the surface, or less than 30 cm thick where the peat lies directly on bedrock. Using our definition of organo-mineral soils, it was estimated that they occupy 30.5 % of Europe’s land surface. The main occurrence of organo-mineral soils in England is in the north and west, especially the Pennines and the Lake District. Organo-mineral soils are found throughout much of Wales, and are typically associated with the upland areas of the Cambrian Mountains, the Brecon Beacons and Snowdonia. More isolated, discrete areas of organo-mineral soils are associated with the moors of south-west and north-east England, along with areas of heathland in the South and low lying areas in East Anglia. Organo-mineral soils occupy approximately 1.6 million hectares of England and Wales or 10.5 % of the land area; when considering Wales alone, this figure increases to 20.5 %. Grassland is the most common land use for organo-mineral soils in England and Wales, but they also occur under cropland, forest and heathland, with more than 40% of heathlands established on organo- mineral soils. In Wales, and to a lesser extent England, organo-mineral soils contribute significantly to the shallow store of soil carbon (C) held by these countries. In England and Wales 14.7% of the total topsoil (0-15 cm) C stock occurs in organo-mineral soils.