Soil compaction in lawns and turf

What is soil compaction


All most all lawns at some time will have suffered from what is known as soil compaction. Soil compaction occurs when a high percentage of the air is squeezed out of the soil by traffic.

Traffic can include lawn mowers, cars and vehicles and people. All of these things contribute to soil compaction. All soils require a high percentage of air to support healthy grass growth.


When the lawn receives a lot of traffic the soil particles are pushed together (compacted) and the air is squeezed out of the soil. Unless steps are taken to relieve compaction the health of the lawn will suffer, resulting in thin and weak grass cover.

Soil compaction is more problematic on clay soils as the particle sizes are smaller, clay soils are generally wetter and the air is squeezed out easily. Although sandy soils can still suffer from compaction, it is usually more severe on heavy clay soils.

The problems caused by soil compaction

Soil compaction has an adverse affect on the health of the soil and lawn including:

  • Available air space is reduced
  • As the pore space diminishes root growth will become poor, the more desirable deeper rooted grasses are replaced by shallow rooted weed grasses.
  • Drought resistance is reduced due to he shallow rooted grasses which suffer badly in dry conditions.
  • Drainage becomes poor as the water sits on the surface of the lawn resulting in water logging.
  • The bacteria in the soil known as micro organisms will disappear as they require air to survive. These organisms naturally degrade the thatch layer (organic matter build up). If there are no micro organisms then the thatch layer will become excessive and have to be controlled by other methods.
  • As the grass cover becomes weaker, it leaves the lawn open to invasion and attack from weeds and disease.
  • When the lawn becomes weak and stressed, it is less responsive to applications of fertilizer with poor nutrient uptake.

Once the above occurs it is time to take action to prevent the lawn deteriorating further. The best method of relieving soil compaction it with lawn aeration.

Preventing and curing soil compaction.

The same method is used to prevent and relieve soil compaction. This is achieved by aerating the soil and a regular basis. If you're not sure if sol compaction is an issue on your lawn, you can test it by inserting a garden fork into the lawn to check the resistance. If it is hard to push in the lawn, then compaction may be a problem and the need for action is necessary.

There are many implements and machines available for the task of lawn aeration. These range from simple garden forks to powered spikers and corers. Lawn aeration should be carried out during the autumn and spring periods. If compaction isn't a problem a single operation in autumn may suffice, if it causes problems aerate in autumn and spring.

It is important to carry on aerating the lawn (at least once a year) to prevent the problem from returning.