Soil Compaction Avoidance Critical

Corn silage harvest has already started, and corn grain and soybean harvests are around the corner. This will be followed by manure that needs to be spread. The heavy loads that will be carried through the fields pose a significant risk of soil compaction. Soil compaction increases bulk density and penetration resistance and reduces aeration, water infiltration, and percolation. Soil compaction leads to greater nitrogen losses due to increased denitrification and greater ammonia volatilization. It reduces phosphorus and potassium uptake because of a smaller root system. Soil compaction also negatively affects soil biota, such as mites, springtails, fly larvae, earthworms, ants, and beetles, because of reduced macropores. The reduced aeration favors anaerobic bacteria that use nitrate or sulfate instead of oxygen for their function, which leads to the production of nitrous oxides, dinitrogen, and hydrogen sulfide gas (rotten egg smell common in swamps). Avoiding soil compaction should therefore be on the forefront of farmer's minds. What can you do to avoid compaction?

1. Use no-tillage, cover crops, and organic inputs to make soil resist compaction. No-till soil is firm, but in a well-managed no-till system, the soil will have lots of macro and micro pore spaces created by a great diversity of organisms living in the soil, while freeze-thaw and wetting-drying cycles also assist in creating new pores. The root systems of cover crops help make the soil resist compaction as well, and soil with high organic matter content has a sponginess to it that helps it resist compaction.
2. Avoid trafficking soil that is in the ‘plastic’ state. The plastic state is when you can easily make a small ball out of soil by kneading it in your hand. Check both surface and subsoil conditions. While you may not have the luxury of waiting with your harvest, you might prioritize soils that dry out first on your farm for harvest shortly after rain. Higher-laying or south-facing slopes typically dry out first.
3. Reduce the trafficked area. Wider equipment means less soil trafficked. However, it is perhaps more important to avoid random truck or grain cart traffic through the field. Instead, try to use travel lanes so compaction is limited to a small area of the field.
4. Reduce surface compaction by lowering the contact pressure. This can be achieved by lowering tire inflation pressure or using tracks. It is still common to see trucks with road tires inflated to 95 psi in farm fields. This should really be a no-no. Common farm tires can now be inflated to 20-30 psi while still able to carry the load, while newer tire technology allows for even lower inflation pressure (even as low as 10 psi). This will greatly help reduce soil compaction.
5. Reduce axle load. Axle load impacts subsoil compaction and should preferably be kept below 10 tons/axle. Higher axle loads have been shown to cause compaction below 12-inch depth when soil is moist. Although the effects of subsoil compaction on crop yields are typically smaller, they can be very long-lasting because it is very hard to alleviate with human means or due to natural processes.