Ipswich, United Kingdom
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Aspray T.J.,Heriot - Watt University | Dimambro M.E.,Cambridge Eco Ltd | Wallace P.,Phil Wallace Ltd | Howell G.,Open University Milton Keynes | Frederickson J.,Open University Milton Keynes
Waste Management | Year: 2015

The purpose of this work was to evaluate compost (and related industry) stability tests given recent large-scale changes to feedstock, processing techniques and compost market requirements. Five stability tests (ORG0020, DR4, Dewar self-heating, oxygen update rate (OUR) and static respiration) were evaluated on composts from ten in-vessel composting sites. Spearman rank correlation coefficients were strong for the ORG0020, OUR and DR4 (both CO2 and O2 measurement), however, OUR results required data extrapolation for highly active compost samples. By comparison the Dewar self-heating and static respiration tests had weaker correlations, in part the result of under reporting highly active, low pH samples. The findings suggest that despite differences in pre-incubation period both dynamic respiration tests (ORG0020 and DR4) are best suited to deal with the wide range of compost stabilities found. © 2015 Elsevier Ltd.

Gregory A.S.,Rothamsted Research | Ritz K.,University of Nottingham | Mcgrath S.P.,Rothamsted Research | Quinton J.N.,Lancaster University | And 7 more authors.
Soil Use and Management | Year: 2015

National governments are becoming increasingly aware of the importance of their soil resources and are shaping strategies accordingly. Implicit in any such strategy is that degradation threats and their potential effect on important soil properties and functions are defined and understood. In this paper, we aimed to review the principal degradation threats on important soil properties in the UK, seeking quantitative data where possible. Soil erosion results in the removal of important topsoil and, with it, nutrients, C and porosity. A decline in soil organic matter principally affects soil biological and microbiological properties, but also impacts on soil physical properties because of the link with soil structure. Soil contamination affects soil chemical properties, affecting nutrient availability and degrading microbial properties, whilst soil compaction degrades the soil pore network. Soil sealing removes the link between the soil and most of the 'spheres', significantly affecting hydrological and microbial functions, and soils on re-developed brownfield sites are typically degraded in most soil properties. Having synthesized the literature on the impact on soil properties, we discuss potential subsequent impacts on the important soil functions, including food and fibre production, storage of water and C, support for biodiversity, and protection of cultural and archaeological heritage. Looking forward, we suggest a twin approach of field-based monitoring supported by controlled laboratory experimentation to improve our mechanistic understanding of soils. This would enable us to better predict future impacts of degradation processes, including climate change, on soil properties and functions so that we may manage soil resources sustainably. © 2015 British Society of Soil Science.

Gregory A.S.,Rothamsted Research | Kirk G.J.D.,Cranfield University | Keay C.A.,Cranfield University | Rawlins B.G.,British Geological Survey | And 2 more authors.
Soil Use and Management | Year: 2014

It is estimated that half the soil carbon globally is in the subsoil, but data are scarce. We updated estimates of subsoil organic carbon (OC) in England and Wales made by Bradley et al. (2005) using soil and land-use databases and compared the results with other published data. We estimated that the soils of England and Wales contained 1633, 1143 and 506 Tg of OC at 0-30, 30-100 and 100-150 cm depths, respectively. Thus, half of the soil OC was found below 30 cm depth. Peat soils accounted for the largest proportion, containing 44% of all the OC below 30 cm despite their small areal extent, followed by brown soils, surface-water gley soils, ground-water gley soils and podzolic soils. Peat soils had more than 25% of their profile OC per unit area in the 100-150 cm depth, whereas most other soils had <8% at this depth. The differences between soil types were consistent with differences in soil formation processes. Differences in depth distributions between land uses were small, but subsoil OC stocks in cultivated soils were generally smaller than in soils under grassland or other land uses. Data on subsoil OC stocks in the literature were scarce, but what there was broadly agreed with the findings of the above database exercise. There was little evidence by which to assess how subsoil OC stocks were changing over time. © 2013 British Society of Soil Science.

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