Good soil management can make a huge difference to productivity, the carbon fixing potential of the soil and the profitability of your business.

Soil Identification

Identification of soil texture
Soil Mapping
Out and about

What is compaction?

  • Soil scientists describe good soil structure as having 50% of the soil volume occupied by particles of soil and organic matter, 25% by water, and 25% by air
  • Compaction describes when soil has been squashed into a solid impermeable layer, either at the surface or within the topsoil. This band of squashed soil restricts the movement of air, water, and nutrients down through the soil profile
  • For more information please click here

What causes compaction?

  • Soil composition and moisture content affect compaction, with wet and clay type soils being more prone to compaction
  • Ground pressure on soils imposed by tracks or wheels
  • Approximately 80% of soil compaction occurs during a machine’s first pass over loose soils
  • Poaching from livestock causes compaction, due to overstocking, or grazing animals in susceptible fields in wet conditions
  • A general increase in the size of machinery and greater use of contractors for forage harvesting and manure spreading
  • On heavy soils with lots of machinery passes, there is a high probability that machinery has to be supported at times where the soil moisture content is higher, which leads to weaker soils, wheel slip and compaction
  • Compaction risks are generally greater at higher soil moisture contents
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How can I identify compaction?

  • Dig a hole to a depth of 30cm when the soil is not excessively wet or dry
  • Notice how far roots and moisture extend down the soil profile, and any obvious changes in soil structure
  • Pay particular attention of any areas where the spade meets resistance. The depth of resistance will help indicate the cause of compaction
  • For more information and to register for a free advice visit from the Soils for Profit scheme, in which compaction can be targeted, please visit the Soils for Profit page.
  • Watch the video at http://www.environment-agency.gov.uk/business/sectors/123420.aspx

Costs of compaction

  • It impacts on a wide range of processes that occur in soil leading to a reduction in yield from the affected field, increased nutrient loss and soil degradation
  • It reduces the ability of grass to utilise fertiliser as the roots cannot fully exploit the soil and reach the nutrients
  • It reduces the uptake of artificial fertiliser - if the soil becomes waterlogged this causes the fertiliser Nitrogen to convert into gases which are lost to the air
  • It reduces the availability of mineralised Nitrogen from soil organic matter and the Nitrogen fixing potential of legumes (including clover)
  • It reduces the crop germination rates, plant seedling establishment and crop emergence
  • There is growing evidence that soil compaction may have implications for flood management, water resources, and soil, water and air quality
  • Compacted soils tend to support less diverse plant species assemblages than soils with better structured profiles
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How to get rid of compaction

    Serious poaching or areas with high levels of runoff must be dealt with quickly to meet cross compliance rules and minimise leaching of nutrients.

  • If the problem is at the surface (0-10cm) consider using an aerator, or introducing organic matter to encourage earthworm activity to break the cap
  • If the problem is slightly deeper (10-15cm) (usually due to machinery), again consider using aeration
  • If the compaction is below 15cm, consider sub soiling or mole ploughing (only in heavy soils)
  • If the compaction is below 15cm consider sub soiling or mole ploughing (only in heavy soils)
  • Make sure that any remedial actions are carried out at the right time for the soil conditions and for the rapid absorption of slurry, to minimise the risk of making the problem worse
  • Remember that soil under an intact grass sward even when the soils are at or near field capacity can be resistant to compaction
  • Organic mineral (higher organic matter content) soils do appear to show greater resilience and resistance to compaction than mineral soils Therefore increasing organic matter in grassland soils through keeping fields in grass for longer (or applying organic manures) could improve the resistance of soils to compaction
  • The introduction of plant species with specific rooting characteristics could help alleviate compaction and improve soil resilience as well as increasing plant and associated biodiversity. The use of species such as chicory, could increase production through improved soil structure and root exploration
  • Watch a video of an aerator from the RDPE Northwest Livestock programme

What are the benefits of removing compaction?

  • Introduction of oxygen to the soil which improves biological and worm activity
  • The physical opening up of the soil structure improves surface drainage and absorption of slurry which helps reduce run off
  • Increased rooting activity which improves the plant’s ability to use nutrients and trace elements
  • More persistent leys with more grazing days per season, and less need for reseeding
  • A more effective microbial population fixes Nitrogen for free, and improves utilisation of applied fertiliser. Grass on uncompacted soil can recover 60% of applied fertiliser , whereas only 26% of applied fertiliser is recovered by the crop in compacted soil (Defra, 2000)
  • Well aerated soils warm up faster in the spring and recover faster after grazing and cutting
  • Increased yields – a potential grassland yield increase of up to 900kg DM/Ha in the following year after addressing compaction issues. A crop of grass silage (£30/t) would result in an extra £108/ha (2006)
  • IGER trials have shown that aeration and the removal of compaction can increase productivity in grazing swards by 26kgDM/Ha/day and also due to the physical opening up of the soil, reducing ammonia losses and boosting the nutrients available to the plant (2006)
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The importance of timing

  • Soil compaction is more closely related to the timing of operations in the field than parameters such as the number of machinery passes and stocking rate
  • Soils are most easily compacted at water contents close to field capacity
  • The timing of stocking and vehicle traffic under “wet” soil conditions is the key factor in determining soil compaction levels rather than the stocking rate, wheel load or number of machinery passes
  • Careful management of machinery use in terms of when and how many times soils are trafficked can have an influence in soil compaction levels
  • Assess soils for the degree and depth of compaction before carrying out any mechanical loosening operations, as loosening when the soils are in good condition can often impact on soil structure and function and reduce dry matter yield
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What to look for in the soil test results

What to look for in the soil test results

Identification of Soil Group

Identification of Soil Texture

Source: Think Soils, Environment Agency