What is the potential for reducing national greenhouse gas emissions from crop and livestock production systems?

Agriculture has a devolved commitment to reduce national emissions of greenhouse gases (GHG). Using a systems model-based life-cycle analysis we explored the potential for reducing GHG in systems used to produce twelve crop and seven livestock commodities. With a functional unit of kg of product, differences in GHG between crops reflect differences in yield. Metabolisable energy (ME) or crude protein (CP) could be used, but deriving an economic value of GB£8.6/GJ ME and GB£0.62/kg CP, leads to a relatively consistent 2.6 kg CO2e/£ nutrient value. Potential GHG reductions ranged from 2% (sugar beet) to 15% (cereals) with agronomic changes, and 4–12% with increased crop yields. The best alternative livestock systems reduced GHG ranging between 7% (beef from the dairy herd) and 21% (extensive sheep meat). Half of the options reduced national production and hence increased imports. Overall, improvements in productivity and use of resources are the best options for reducing GHG