For typical cereal and oilseed rape crops 40-50% of greenhouse gas (GHG) emissions are associated with nitrogen (N) fertiliser, 15% with the application of organic materials, 13-20% with field operations (such as cultivations), and 12-24% with the decomposition of crop residues.

Nitrogen fertiliser

N fertilizer is the greatest source of GHG emissions for most arable crops. Therefore, approaches that maximise the efficiency of N use and support high crop productivity must be prioritized. These include:
⦁ Create a N management plan
⦁ Cover crops to reduce the risk of nitrate leaching
⦁ Estimate/measure the soil N supply to help estimate how much N fertilizer to apply
⦁ Use N fertilizer products produced with low GHG emissions associated with manufacture
⦁ Use fertilizer efficiency additives including urease/nitrification inhibitors

Cultivations

Cultivations represent between ~5% and ~50% of total GHG emissions per ha. A cultivation system involving plough, power harrow, drill, roll produces >200 kg CO2/ha on a loam soil. By contrast, direct drilling produces <50 kg CO2/ha. Soil type has a large effect on GHG emissions, e.g. ploughing clay soil requires 70% more energy than loamy soil.
Adopting low intensity cultivations, e.g. direct drilling, may not be appropriate for all soil types and farming systems. Farmers should introduce new cultivation systems gradually and test they are appropriate for their farm.

Actions
⦁ Prioritise efficient use of N fertilizer
⦁ Adopt low intensity cultivations but take care to ensure they are appropriate for your farm