Scotland is committed to meeting a net-zero target for greenhouse gas (GHG) emissions by 2045. Agriculture and the land use sector can help in two ways: by changing practices to reduce GHG emissions and by storing carbon in the soil and plants. In 2018 agriculture and related land use was responsible for 23% of total Scottish emissions. Emissions from agriculture have fallen by 30% since 1990, compared with a reduction of 45% across total emissions (Scottish Government 2020).
The Climate Change Plan (CCP) is a key policy tool which was revised in December 2020 (after this research was completed) to help Scotland meet the new net-zero target. Policy development is informed by the Scottish ‘TIMES model’. This model pulls together emission, mitigation and mitigation cost data from all sectors to help understand the strategic choices required to decarbonise an economy. It identifies the effectiveness of carbon reduction measures to enable a consistent comparison of the costs of action across all sectors.
To ensure the model uses the most recent data for agriculture, our research updated estimates of the mitigation potential and the cost-effectiveness of a selection of agricultural mitigation options. It took into account the significant recent improvements in UK agricultural GHG inventory reporting (Smart Inventory).
We assessed 14 farm technologies and practices which can reduce GHG emissions in Scotland. Some of these measures can be applied to multiple types of livestock, raising the number of mitigation options to 21.
The aim was to estimate the different measures’ average mitigation potential, capital and recurring costs per unit (e.g. hectare or animal), and total maximum applicability on-farm. This research considers average estimates. On an individual farm basis, both the mitigation and the net costs can be very different.
- The mitigation measures applicable to agricultural land can save between 7 and 151 kg CO2e every year on each hectare where they are applied. The single most effective measure is increased cultivation of grain legumes (i.e. peas and beans) which provides 553 kg CO2e per hectare savings annually (see Table 1). The second and third most effective measures (on an area basis) are variable rate nitrogen and lime application (precision farming) and soil pH management (i.e. liming when necessary), providing 151 and 112 kg CO2e mitigation per hectare annually, respectively.
- Intercropping can provide the highest cost savings to farmers per hectare per year (£45); variable rate nitrogen and lime application, crop varieties with higher nitrogen use efficiency and soil pH management can also provide savings. Grain legume cultivation is the most expensive option (£406 per hectare per year).
- The cattle mitigation measures assessed can save between 57 and 854 kg CO2e every year for each animal they are applied to; 3NOP feed additive, breeding for low methane emissions and slurry store cover with impermeable cover are the most effective.
- Cattle measures’ net costs range from a saving of £359 to a cost of £31 per animal per year. The dairy breeding measure could save £359 per animal per year, and improved health of dairy animals, dairy precision feeding, beef breeding for low methane emissions and covering beef slurry stores can also save farmers money. The most expensive cattle measure is administering 3NOP feed additive to beef animals (£31 per animal per year).
- The sheep measure investigated can provide 15 kg CO2e mitigation per animal annually and a cost saving of £0.36 per head.
- The two measures applicable to pigs could reduce emissions by 25 and 86 kg CO2e per head per year, for a £0.87 saving or cost of £0.52 per animal per year, respectively.
It is important to note that these are average estimates. On an individual farm basis, both the mitigation and the net costs can be very different. For example, the livestock health measures cover a wide range of possible actions (which would be demanding to assess individually). Therefore, depending on the health status of the animals and the implemented change, the GHG benefits achieved and costs could vary widely.