The potential to increase soil carbon stocks through reduced tillage or organic material additions in England and Wales: A case study

• Published in: Agriculture, ecosystems & environment Vol. 146; no. 1; pp. 23 - 33
• Main Authors: Powlson, D.S., Bhogal, A., Chambers, B.J., Coleman, K., Macdonald, A.J., Goulding, K.W.T., Whitmore, A.P.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2012
• Subjects: animal manures; Biosolids; Carbon; carbon sinks; case studies; climate change; Climate change mitigation; composts; conventional tillage; emissions; farmers; Farms; landfills; Long-term experiments; Manure; nitrous oxide; Nitrous oxides; Organic amendments; Reduced tillage; soil; Soil (material); Soil carbon stocks; Soil organic carbon; Soil organic matter; Straw; Tillage; England; Wales; British Isles, England; Europe; British Isles, Wales; Long-term experiments; Soil carbon stocks; Soil organic matter; Organic amendments; Climate change mitigation; Soil organic carbon; Reduced tillage; Biosolids
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/j.agee.2011.10.004

► Scope for increasing UK SOC by reduced tillage at best 310 ± 180 kg C ha −1 yr −1. ► Potential sequestration from added OM largely limited by availability and current use. ► Many activities that benefit SOC are a part of current practice. ► Green compost offers greatest potential to increase SOC stock. ► Benefits from increasing soil carbon may be offset by N 2O emissions. Results from the UK were reviewed to quantify the impact on climate change mitigation of soil organic carbon (SOC) stocks as a result of (1) a change from conventional to less intensive tillage and (2) addition of organic materials including farm manures, digested biosolids, cereal straw, green manure and paper crumble. The average annual increase in SOC deriving from reduced tillage was 310 kg C ± 180 kg C ha −1 yr −1. Even this accumulation of C is unlikely to be achieved in the UK and northwest Europe because farmers practice rotational tillage. N 2O emissions may increase under reduced tillage, counteracting increases in SOC. Addition of biosolids increased SOC (in kg C ha −1 yr −1 t −1 dry solids added) by on average 60 ± 20 (farm manures), 180 ± 24 (digested biosolids), 50 ± 15 (cereal straw), 60 ± 10 (green compost) and an estimated 60 (paper crumble). SOC accumulation declines in long-term experiments (>50 yr) with farm manure applications as a new equilibrium is approached. Biosolids are typically already applied to soil, so increases in SOC cannot be regarded as mitigation. Large increases in SOC were deduced for paper crumble (>6 t C ha −1 yr −1) but outweighed by N 2O emissions deriving from additional fertiliser. Compost offers genuine potential for mitigation because application replaces disposal to landfill; it also decreases N 2O emission.