Abstract
The overall aim of this project is to critically review to what extent reduced tillage practices and organic matter returns will increase the carbon content of arable soils under English and Welsh conditions. The 2006 UK Climate Change Programme includes a policy commitment to "examine the scope and feasibility of a market based mechanism to facilitate trading of greenhouse gas reductions from agriculture, forestry and other land management sectors". Both reduced tillage and the recycling of organic materials have been promoted as a means of sequestering carbon in agricultural soils. However, a Defra-funded review of the potential for carbon sequestration in agricultural soils (SP0523, 2003), concluded that with respect to land management, there was more potential for saving carbon in terms of fuel use than would be sequestered in soil under UK conditions. For zero tillage systems, potential increases in nitrous oxide emissions would also more than offset any carbon sequestered. The review also showed that there was only limited potential to build-up soil carbon from the application of organic materials, and it questioned the current focus on the sequestration of carbon to soils as the primary reaction of agriculture to greenhouse gas abatement. Since this review, there has been renewed interest in the use of reduced tillage and organic matter additions in the mitigation of climate change, particularly following publication of the Stern report on the economics of climate change (which promotes reduced tillage). This project will build on the earlier review (SP0523) and examine more recent evidence to determine the potential for increasing soil organic carbon by reduced tillage (including zero tillage) and organic matter additions (farm manures, biosolids, composts, paper waste etc), including new data from field experiments in England and Wales. This will also include an evaluation of other environmental and economic implications of the adoption of such practices, and the overall greenhouse gas balance. The project will enable Defra to develop a clear line on whether carbon sequestration by changed land management practice is both scientifically plausible and measurable, and whether it has the potential to be included within any incentive scheme.
United Kingdom