How can ploughing help improve soil structure to increase crop yields?

Soil compaction can occur due to natural phenomena, such as heavy rainfall or irrigation, as well as from the repeated use of farm machinery. A heavily compacted soil restricts both soil aeration and water infiltration. This compromises the soil's overall functionality and limits the ability of plant roots to explore and access vital nutrients. To restore your soil’s superpowers, several strategies can be employed to improve its structure, quality, and fertility.

Assessing the level of soil compaction

According to ARVALIS, any corrective action for improving soil structure (surface tillage, deep tillage, ploughing) should be based on a diagnostic assessment that evaluates the intensity and depth of compaction: the deeper the compaction, the more difficult it is to reverse. It’s also important to assess how sensitive the crop to be planted is to soil compaction.

If, upon inspection, the soil structure shows no signs of compaction or compacted zones, then restructuring is not needed. However, if the field shows severe compaction, then action should be taken to restructure the soil by addressing three key questions:

• Is the crop sensitive to compaction?
• What is the degree of compaction in the field?
• How deep is the compaction?

Crops that are sensitive to compaction require restructuring as soon as compaction is observed, even if natural regeneration has already begun. On the other hand, for less sensitive crops, such as wheat, soil regeneration is only needed if the compaction is severe and the soil displays hydromorphic characteristics. The table below can assist in evaluating compaction levels and, based on the findings, determine the most effective corrective strategies to implement.

Need for regeneration based on the intensity of compaction and crop sensitivity

Some soils are particularly prone to compaction:

• Sandy soils: these soils are less affected by climate in terms of natural restructuring. Additionally, they tend to have fewer earthworms compared to other soil types. Yet earthworms, along with other soil organisms such as micro-organisms, insects, and plant roots, play a critical role in the natural restructuring process.
• Clay soils are impermeable and highly susceptible to compaction. During winter, they tend to become waterlogged and sticky, then harden into dense clumps when they dry out in summer.
• Calcareous soils are generally light, although some variations can be heavier. These soils retain minimal moisture, which increases the risk of compaction. In summer, they dry out rapidly, and the frequent presence of stones can make tillage more difficult.

The plough, the ideal tool for correcting severe compaction

According to ARVALIS, when soil structure is degraded, the regeneration capacity driven by climate and biological activity differs by soil type and often takes several years. The autumn harvests of 2023 and 2024 were not conducted under optimal conditions and caused damage to the fields. Additionally, the few frost events during the 2024/2025 winter were insufficient to significantly improve the soil structure. Given the farmer’s objectives, ploughing may therefore be necessary.

“Some may choose to stick with no-till methods, even if it means, for example, giving up on sowing wheat late in the season, says Jérôme Labreuche, agronomist at ARVALIS. It can be more challenging, but it all depends on their priorities.”

While ploughing can be performed under a wide range of moisture conditions, deep tillage requires soil to be friable. In recent years, particularly dry summers have made it impossible to perform deep tillage before establishing cover crops.

“There are many misconceptions about soil fertility. Ploughing is often criticised for supposedly sterilising the soil. However, we have observed good soil fertility in situations where ploughing was done properly. The issue is often not with the practice itself, but with the conditions under which it is applied. It is important to intervene at the right time, on well-drained soil, and ideally at a depth no greater than 20 cm.” notes Jérôme Labreuche.

Yvan Gautronneau, former instructor at ISARA Lyon (French engineering school specialised in agronomy, agri-food, and environment), offers practical guidance on how to use the plough effectively to restore soil structure and promote soil health through agronomic ploughing:

1. Perform shallow ploughing.
2. Choose 12- or 14-inch ploughs to ensure better distribution of organic matter across the field.
3. Use on-land ploughing methods to accommodate tractors fitted with low-pressure, wide, dual, or track tyres.
4. Plough every 2 to 3 years, depending on the specific characteristics of each field.
5. In loamy or well-balanced soils, perform stubble ploughing post-harvest to reduce the risk of gradual compaction buildup over time. Use a straight-tine stubble cultivator for deep soil loosening.

Preventing compaction upstream

Limit traffic across the field

Minimise the number of machinery passes over the field to reduce the risk of long-term compaction. Field-based geolocation systems (GPS or RTK) can help to precisely define traffic lanes, thereby minimising wheel tracks. Livestock (cattle, horses, pigs) can also cause significant compaction in high-traffic areas, particularly around feeding or watering zones. On temporary pastures, it is recommended to construct stabilised pathways to guide animal movement.

Work on well-drained soils

Performing fieldwork under wet conditions can significantly degrade soil quality. In recent years, narrow weather windows have made sowing and harvesting more challenging. When compaction is confirmed, deep tillage through ploughing is recommended to regenerate soil structure and protect the productivity of future crops. Excess moisture impairs water infiltration and leads to root asphyxiation. Ploughing helps correct these negative effects and improves soil porosity.

Work on friable soil

Ploughing can be performed across a wider range of moisture conditions than other tillage tools. Deep tillage requires friable soil. Therefore, it is important to test the soil's friability by manually applying pressure to a clod:

• If the soil crumbles without sticking (or only slightly, for clay soils) and forms fine earth, this indicates that the soil is friable and deep tillage can be performed;
• If the soil crumbles but sticks together and forms balls, or deforms, the soil is too moist, and there is a high risk of smearing or creating clods;
• If the soil is difficult to break and produces little fine soil, it is too dry, and deep tillage will be ineffective.

It’s important to note that surface observation alone is not sufficient. You must verify friability at depth.

Adapting tyres to reduce soil compaction

Tyres play a significant role in soil compaction and can create ruts that damage fields. According to ARVALIS, tyre-induced compaction can result in yield losses of up to 15–20 quintals per hectare. Fortunately, there are solutions to minimise this impact, provided that operations are carried out on sufficiently drained soil.

Central tyre inflation systems

This innovative technology enables quick adjustment of tyre pressure depending on whether the tractor is on the road or in the field. On the road, tyres experience less wear, last longer, and the risk of overheating or damage is significantly reduced.

In the field, ground pressure is minimised, leading to shallower ruts, improved traction, and better soil structure preservation. The tyre’s footprint becomes wider and longer, enhancing grip. Additionally, wheel slip can be reduced by up to 20%. Fuel consumption can be lowered by up to 10% on the road and 10–15% in the field.

Today, many tractors come partially equipped for central tyre inflation systems, making the technology more affordable and accessible.

Establishing perennial plants and plant cover

After mechanically restructuring the soil to restore porosity, it is essential to maintain that structure and prevent the downward movement of fine particles and surface erosion caused by rainfall or winter soil compaction. The most effective solution is rapid colonisation of the soil by plant roots, either through cover crops or planted plants.

Service plants, or cover crops planted before or alongside a cash crop, are designed to support current or future crops in the rotation. They enhance the soil’s chemical, biological, and physical fertility by capturing nitrogen for the benefit of the main crop, attracting pollinators while reducing harmful organisms (weeds, diseases, pests), stabilising soil structure.

Cover crops also protect the soil from crusting, erosion, and run-off. Their roots prevent clodding, and improve porosity and water absorption, especially in clay soils. While Brassicaceae (such as radish, rapeseed, mustard, or turnip) have beneficial taproots for soil structure, they struggle in compacted soils where their roots often twist or split. In such conditions, cover crops may be more effective for accelerating drainage by accelerating drainage and water retention.

Perennial crops (alfalfa, white clover, orchard grass, fescue, or ryegrass) have far more robust root systems than annual crops. These extensive root systems provide long-term benefits for soil structure.

Moreover, perennial plants promote photosynthesis, which is vital for regenerating soil life.
They capture CO₂ and supply nutrients to soil micro-organisms, enhancing the soil’s biological, chemical, and physical health, making it more fertile and resilient.

Adding organic matter

Adding organic matter into the soil enhances its resilience against disaggregation, compaction (structural stability). Organic matter forms stable organo-mineral complexes which provide the soil with plasticity. Organic matter also plays a crucial role in maintaining soil porosity, which ensures proper air and water circulation, essential for healthy soil function.

The organic matter content and calcium levels in the soil directly influence its resistance to compaction. Both factors contribute to the formation of clay-humus complexes and calcium bridges, which help bind soil particles together, reducing the likelihood of structural degradation.

Adding organic matter, whether through chemical or organic fertilisers, boosts the activity of soil organisms (earthworms, bacteria, springtails, nematodes, etc.). These beneficial organisms, such as earthworms, play a crucial role in breaking down organic matter into nutrients that plants can absorb. As they move through the soil to feed or seek shelter, these living organisms create spaces and help structure the soil. Their activities aerate the soil, drain it, and help reduce soil erosion. The spaces they create enhance root penetration, while also improving access to water and oxygen.

It is essential to assess the severity of compaction before taking action. In the case of severe compaction, ploughing remains one of the most effective tools to deeply restructure and loosen the soil. Ploughing should be performed under sufficiently dry conditions and at the correct depth. For compaction below 30cm, certain tine-equipped tools can also be highly effective. 

To prevent soil compaction, several strategies can be implemented: limit the number of heavy machinery passes over the field, allow the soil to dry before intervening, work the soil when it is friable, adapt tyre equipment (dual wheels, low-pressure tyres, central inflation systems), establish soil-improving crops, and apply organic matter to enhance soil fertility and structure. 

Sources:

• https://www.firestone-agriculture.eu/blog/how-do-my-agricultural-tyres-impact-soil-compaction
• https://www.agroscope.admin.ch/agroscope/en/home/topics/environment-resources/soil-bodies-water-nutrients/soil-quality-and-use/project-strudel.html
• https://wiki.tripleperformance.fr/wiki/Stabilit%C3%A9_structurale_d%E2%80%99un_sol
• https://www.perspectives-agricoles.com/sites/default/files/imported_files/397_284578109318259179.pdf
• https://www.terre-net.fr/travail-du-sol/article/176106/le-labour-rend-service-et-ne-tue-pas-les-sols
• https://www.inrae.fr/actualites/agriculture-conservation-se-passer-labour-pas-si-facile
• https://www.terre-net.fr/travail-du-sol/article/225569/faut-il-encore-labourer-ou-pas-l-eternelle-question
• https://www.arvalis.fr/sites/default/files/imported_files/381_9147297284832421500.pdf