How to avoid soil compaction during harvest

With harvest well and truly progressing across the country coupled with recent rain events, this has created challenging conditions for many farmers. These wet conditions and traffic from heavy equipment, can make the soil susceptible to compaction, weakening the soil structure and possibly causing significant surface compaction, rutting and deep subsoil compaction. Damage from soil compaction can have a significant impact on water infiltration, root development and ultimately yields the following season.

What is rutting?

Rutting occurs when tires sink into wet soils causing trenches or furrows. This can displace soil, cause damage to soil structure and ultimately cause issues for the succeeding crops.

What is compaction?

Compaction occurs when soils are near saturation. The water in the soil acts as a lubricant, allowing soil aggregates to be destroyed and soil particles to be compressed together, forcing out the water.

How can you minimise soil compaction during harvest?

How you approach fieldwork after heavy rain events can impact your soil for future growing seasons.

Here are a couple of tips:

Studies show that 60-80 per cent of soil compaction occurs by the first wheel passes. Many farmers use “on-the-go” unloading into a grain cart. In areas that have received excessive rainfall, consider having dedicated travel lanes.
Where possible, avoid loading machinery at full capacity. Reduce the axle loads by not loading them to full capacity.
Ensure tire pressures are correctly adjusted to match the axle load that will be carried. Larger tires with lower air pressure provide more surface area, allowing for better flotation and reduced pressure on the soil surface.
Harvest around the wettest areas. The wettest areas are the most at risk for soil compaction. Where possible, come back to these areas once the soil conditions are drier.
Clay soils are more prone to compaction as compared to sandy soils. If you have paddocks with both, it may be appropriate to harvest the sandier paddocks first.
Avoid or limit tillage – hold off tillage operations until soil conditions are drier than paddock capacity. It is important to consider the soil moisture at the depth of tillage, as tillage in wet conditions results in further compaction and smearing of soil instead of the intended fracturing of the soil.

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