Delivering on net zero: Scottish Agriculture

Summary in the original language of the document

The aim of this study was to identify whether, how and at what cost agricultural GHG emissions in Scotland could be reduced by 35% by 2045. In 2017, Scottish agricultural GHG emissions were estimated to be 7.6 Mt CO2e making the 35% target 2.7 Mt CO2e.
Building on previous work by SRUC and others, 37 different measures to reduce GHG emissions were evaluated, focusing on improvements in nitrogen fertiliser use, organic manure/slurry storage and use, mechanisation, soil management, cropping systems and management, livestock nutrition, health and breeding, as well as improved farming systems integrating multiple measures, represented by conservation agriculture, organic farming, pasture-fed livestock production and agroforestry.
Land use changes, such as from agriculture to peatland or forestry, as well as non-agricultural activities (including input manufacturing, food processing, retailing and consumption) were outside the scope of the study, although consideration was given to food losses on farms arising from decisions in other sectors. Embodied GHG emissions in inputs and impacts of output changes on other countries were also not assessed.
In theory, if taken up 100% and accounting for no interactions, the measures could reduce Scottish agricultural emissions by almost 100%. In practice, there are many reasons why measures might not be implemented in combination, or adopted, by all farmers. We estimated that the most promising measures could potentially deliver 2.9 Mt CO2e annually, or 38% of 2017 GHG emissions, and concluded that the 35% target is achievable by 2045.
75% of Scottish agricultural GHG emissions are related to livestock production. This is not surprising given the importance of grassland and rough grazing in Scottish agriculture, which together account for almost 80% of agricultural land. Given this context, measures focused on tillage crops are relatively unimportant with respect to their potential for GHG reduction. The measures with most potential (all specified on annual basis) that we identified were:
a) Reduction in nitrogen fertiliser use. Measures to use nitrogen more efficiently, including better use of organic manures, could potentially generate reductions of nearly 350 kt CO2e, or 13% of the target, within the next 10 years, if adopted on most farms.
b) More radical reductions in nitrogen fertiliser use, by encouraging the use of legumes in grassland to eliminate or substantially reduce the need for N fertiliser, could reduce emissions by nearly 300 kt CO2e, or 11% of the target, within the next 15 years, if adopted on 40% of grassland.
c) The use of legumes combined with rotational grazing techniques in diverse-species grassland, which help build soil organic matter and sequester carbon, could increase the total benefit to 540 kt or 20% of the target. This could potentially be linked with a pasture-fed livestock approach.
d) Reducing methane emissions associated with ruminants by using feed additives including 3NOP, nitrates, probiotics, high dietary fat sources and seaweed derivatives could make a significant contribution. In the case of 3NOP, emissions could be reduced by 265 kt or 10% of the target within 10 years, if adopted on most dairy and some other cattle farms. This would require approval of 3NOP as a feed additive so that it can be marketed, and that at an affordable price.
e) Improved animal health and breeding, with increased fertility, growth rates and yields, and reduced morbidity/mortality could reduce total livestock numbers needed to deliver the same output, and deliver 366 kt emission reductions (14% of the target) with 40-50% uptake.
f) Organic farming, with 40% uptake, could potentially deliver 730 kt CO2e reductions or 27% of the target. This is a result of combining no synthetic nitrogen fertiliser use with an overall 10% reduction in livestock numbers and the conversion of 20% of tillage land to rotational grassland. The financial impacts of these changes are reduced due to the premium markets for organic food.
g) Agroforestry also offers potential for substantial reductions: 570 kt (21% of the target) with 30% uptake. This is assuming 10% of farmland is used for trees, with consequent output reductions for crops and livestock, although with some scope to mitigate this.
Despite their emission reduction potential, organic farming and agroforestry both have the disadvantages of higher initial investment costs, greater complexity acting as a disincentive to adoption and longer lead-in
times, as well as output reductions that, if demand remains unchanged, could lead to an increased requirement for imports and increased emissions elsewhere. However, the widespread adoption of these approaches would need to be considered in the context of changing human and animal diets, and the potential for reducing food losses and waste also highlighted in the report.
The financial assessment of these measures indicates that many are likely to be associated with increased costs and, in the absence of other financial benefits, reduced incomes, which would need to be addressed by policy support in some form. In several cases, reductions in nitrate leaching, ammonia emissions and other impacts leading to improvements in water and air quality could provide further justifications for support. In some cases, the improved productivity, for example associated with improved animal health and breeding, could create a win-win situation, with emissions reduction combined with financial benefits.
As most of the measures are unlikely to be driven by market forces, policy interventions are likely to be needed, including:
• Farming system payments for innovative approaches (whole or part farm)
• Input reduction and improved soil management, including support for advice and investments
• Regulatory and fiscal options including input taxes and quotas or tradeable carbon quotas linked to input use and sequestration opportunties
• Carbon, nitrogen and sustainability auditing
• Training, advice and skills
• Improved greenhouse gas monitoring and statistics
• Targeted research, and
• Dietary change and food waste reduction
In almost all cases, the practices and systems that could be adopted are well developed and understood, but actions are needed to ensure that financial and knowledge barriers are addressed in order to facilitate their adoption so that the desired GHG mitigation targets can be achieved.