Reducing emissions by alleviating soil compaction

Alleviating soil compaction can help reduce greenhouse gas emissions by improving soil structure, enhancing aeration, and promoting healthier microbial activity, which supports more efficient nutrient cycling and reduces nitrous oxide release.

Soil compaction can be caused by machinery (trafficking) and livestock (trampling and poaching). Soil compaction restricts the movement of air, water and nutrients through the soil profile, directly affecting the growth of crops and grass. Roots may struggle to penetrate compacted layers. This limits access to essential nutrients and moisture. As a result, plants become more vulnerable to stress, and farmers may see increased weed pressure, higher susceptibility to disease, and reduced yields.

Soil compaction restricts water movement, nutrient availability, oxygen flow, and root development – factors that directly reduce crop and grass growth and yield. This not only impacts profitability but also raises greenhouse gas (GHG) emissions per tonne of crop produced, making compaction both an economic and environmental concern.

Compacted soils are also more likely to release higher levels of nitrous oxide (N₂O) – a potent greenhouse gas with a global warming potential nearly 300 times that of carbon dioxide. Additionally, reduced root growth and crop performance limit the return of organic carbon to the soil, potentially lowering soil carbon sequestration. Compaction may also increase nutrient losses, contributing to water pollution.

Studies have shown that alleviating soil compaction can improve yields and reduce emissions, although outcomes depend on several factors:

• Soil type
• The severity and extent of compaction
• The depth and location of compaction within the soil profile

Trials investigating the role of cultivation in reducing N₂O emissions have produced mixed results, highlighting the need for site-specific approaches and careful management.

Ultimately, when the same level of inputs results in reduced output, the emissions per tonne of product increases, making compaction a critical issue to address for both productivity and sustainability.

While preventing soil compaction is always the best approach, repairing existing damage – such as breaking up soil pans – can deliver strong returns. Even if it involves upfront costs, restoring soil structure improves productivity, making the land more resilient and more profitable in the long run.

• Plan work around soil moisture – carry out field operations and cultivation when soil is at the right moisture level.
• Manage livestock in wet conditions – reduce stocking density during wetter periods to prevent hoof damage
• Check and improve drainage – regularly assess drainage effectiveness and address any issues
• Use the correct tyre pressure and design: 
  • Tyre pressure is important. For example, when seedbeds are being prepared lower pressure will spread the weight of the machine over a wider area to protect the soil
  • The design of tyres is a factor too – super singles trailer tyres concentrate the carried weight into a very small contact area leading to compaction. Wider, more flexible floatation tyres are more forgiving to soil structure
• Choose lighter machinery:
  • Where applicable, use lighter or smaller machines to minimise risk
  • Remove wheel weights and weight blocks when they are not needed
• Use controlled traffic farming (CTF) – CTF, a system which involves all machines following the footprint of designated tramlines, reduces the area of soil surface that comes under pressure from field operations
• Consider low-impact cultivation techniques – If there is no compaction present, direct drilling or other forms of cultivation that don’t substantially turn the soil profile can reduce future compaction compared to ploughing
• Ensure good levels of organic matter:
  • Ensuring good levels of organic matter keeps soils loose
  • Organic material keeps the soil structure open