Revised estimates of the carbon mitigation potential of UK agricultural land

The soil sequestration components of recent estimates of the carbon mitigat ion potential of UK agricultural land were calculated on the basis of a per centage change to the soil carbon stock present in the soil. Recent data su ggest that the carbon stock of soil in UK arable land has been overestimate d, meaning that potential soil carbon sequestration rates were also overest imated. Here, we present a new estimate of the carbon stock in UK arable la nd, and present revised estimates for the carbon mitigation potential of UK agricultural land. The stock of soil organic carbon in UK arable land (0-3 0 cm) is estimated to be 562 Tg, about half of the previous estimate. Conse quently, the soil carbon sequestration component of each mitigation option is reduced by about half of previously published values. Since above-ground carbon accumulation and fossil fuel carbon savings remain unchanged by the se new soil carbon data, options with a significant non-soil carbon mitigat ion component are reduced by less than those resulting from soil carbon seq uestration alone. The best single mitigation option (bioenergy crop product ion on surplus arable land) accounts for 3.5 Tg Cyr(-1), (2.2% of the UK's 1990 CO2-carbon emissions), whilst an optimal combined land-use mitigation option accounts for 6.1 Tg Cyr(-1) (3.9% of the UK's 1990 CO2-carbon emissi ons). These revised figures suggest that through manipulation of arable lan d, the UK; could, at best, meet 49% of its contribution to the EU's overall Kyoto CO2-carbon emission reduction target (8% of 1990 emissions), and 31% of the greater target accepted by the UK (12.5%). Even these reduced estim ates show a significant carbon mitigation potential for UK arable land.