This fall has seen heavier than normal precipitation in a large area of the Corn Belt. According to the University of Minnesota, as of mid-September, Minneapolis has had the second wettest year on record. This is a cause for concern for many farmers as heavy moisture and wet fields can lead to heavy harvest equipment causing ruts and soil compaction.
Analyzing Ruts and Compactions
Researchers at the University of Minnesota Extension studied the effect these ruts and compactions have on corn yields. To do this they performed a GPS analysis on seven pairs of ruts and non-rutted areas in four fields. The researchers tracked corn height, population and growth stages during the growing season. They found that plant population was not statistically different between the rutted and non-rutted areas, but the non-rutted corn was 8.5 in. taller and one growth stage ahead of the rutted corn.
After hand harvesting the observation area in the fall, the final population, grain moisture and corn yield were measured. While most areas weren’t affected, yield was dramatically decreased at 28 bushels per acre less in the rutted areas. This equated to an average 17 percent yield decrease over all seven sites.
Why Soil Compaction Hurts Yields
Compaction hinders plant growth and development, creating an environment for poor root system establishment. This leads to nutrient deficiencies and the reduced ability for nutrient uptake. Compaction decreases pore space in the soil and reduces its ability to filter water down. Whereas, a well-structured soil holds and conducts water, nutrients and air–all of which are necessary for healthy plan root activity.
How to Reduce Compaction
Compaction is more likely to occur when soil is wet, amplifying the damage heavy equipment and tillage implements have to the soil’s structure. The first step to minimizing soil compaction is to stay out of those wet fields when soil moisture is at or near field capacity, and let the field dry out before taking any heavy equipment into it.
Deep tillage can help break up the hard pans that can form deeper in the soil. But, University of Minnesota researchers note that the research has shown that it doesn’t improve overall soil structure and the benefits are usually limited to shorter time periods.
Equipment tire size and pressure can also impact compaction. Larger wheels and tires allow for better floatation and lower tire pressure spreads out the tire area, reducing the load on the soil. According to Iowa State University Crop Extension, researchers found that soil farmed with equipment exerting a maximum of 6-psi surface pressure yielded nine more bushels of corn per acre than soil farmed with more conventional tires exerting 16-psi surface pressure. Radial tires can be inflated as low as 6 to 8 psi, but growers should check in with their equipment dealer to confirm proper tire pressure.
Soil compaction can become a significant issue, but it can be addressed through management. Avoiding field operations when the soil is wet, use deep tillage when soil is dry enough to shatter, and consider the benefits of conservation tillage. Conservation tillage is the best long-term solution as it doesn’t disrupt the soil structure as much.
For more information, talk to your local agronomist or ag retailer.