Compaction

What is it?

Compaction is the dense packing together of soil particles such that the pore space is decreased. Compaction decreases the permeability of the soil to gasses and water, and root penetration and micro-organism activity are restricted.

Additional information on compaction is available in the soil health section of the VRO website.

Photograph of a compacted zone of soil immediately below the plough layer in a cropping soil

Impact

Compaction occurs as a result of trafficking and cultivation. It is exacerbated by high soil moisture contents.

The reduction in pore space (and it is usually the larger pores which are destroyed) decreases the habitat available for roots and soil organisms. As a consequence it reduces biological activity in the soil leading to decreasing rates of soil organic matter cycling and nutrient availability. It also decreases soil permeability, aeration, water holding capacity, drainage, seedling emergence and root exploration.

Management

The starting points to avoiding soil compaction are: minimise cultivation; avoid working soils when wet; reduce and control traffic, and contain animal movement on moist soils.

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