Soil compaction: meaning, effects and prevention

Soil compaction is the process by which air comes out from the pores between soil grains, causing soil densification and preventing water and air penetration. In addition, this process causes a loss of volume in the soil mass, which can impact crop production, as well as the physical and chemical properties of the soil.

This compaction process occurs due to external forces acting on the soil, mainly:

• Soil tillage tools.
• Loads produced by tractor tyres and dragging tools (this is aggravated if the land is wet).
• Application of products that create surface crusting.
• Impact of water droplets.

However, compacted soils can also be found in natural circumstances, given the conditions that prevailed during their formation and evolution.

WHAT PROBLEMS DOES SOIL COMPACTION CAUSE AGRONOMICALLY?

We can say that the ideal soil structure is 50% soil, 25% water space and 25% air space. This structure responds to the roots need for water and oxygen for their development, and an adequate pore space between soil particles in order to grow.

The increase in soil density caused by compaction decreases the total porosity and the macroporosity (aeration porosity) of the soil, with the following effects:

• Smaller plants.
• Visible patterns of patches or stands of stunted plants within the crop.
• Abnormalities in root growth.
• Lack of nutrients in the crop, which in turn can be another reason for compaction.
• Surface water or erosion caused by water.

IMAGE 1: PLANT DEVELOPED ON NON-COMPACTED SOIL (A) AND ON A COMPACTED SOIL (B).

HOW TO PREVENT SOIL COMPACTION?

The above effects and thus soil compaction can be prevented by taking the following actions:

• Incorporating organic matter into the soil, as this promotes the formation and stability of the soil structure.
• Making use of cover crops, which produce continuous pores through the penetration of their roots and their death, helping air and water move in the soil, while incorporating organic matter.
• Using ridges for the tractor tracks and haul roads, preventing the effect of compaction from reaching greater depths and the unnecessary passage of machinery over the soil surface.
• Adjusting the machinery to the same trail, so that the area used by the machinery is reduced and a single track is used for the passage of the wheels.
• Applying  HEROSOIL from Herogra Especiales, a product designed to recover water infiltration and aeration capacity in soils with compaction and low permeability issues.
• Reduces the formation of surface crusting.
• Improves aggregation and reduces clay dispersion.
• Increases soil fertility.
• Reduces soil salinity.
• Restores water infiltration and aeration in soils.
• Improves the water holding capacity of the soil.