I’ve seen more fields with harvest ruts this year than I usually do. There were several weather-related factors that contributed to this situation. The wet spring led to planting delays, delaying crop maturity. However, two weather anomalies in 2017 (seven consecutive days above 90 degrees Fahrenheit in September and the wettest October on record) were the main factors.
The hot and dry weather in September caused soybeans to dry down rapidly, and in many cases the crop was overly dry, having moisture contents of 8 to 9 percent. This situation reduced the net value per bushels by $0.20 to $0.40 due to the lost moisture weight in the grain and increased the potential for harvest losses due to shattering.
Producers that decided to not harvest the overly dry soybeans in September, or were not able to harvest due to late-maturing crops, missed out on ideal harvest soil conditions and ended up harvesting some of their fields when the soil was too wet. As a result, harvest equipment left ruts in these fields. In some cases, the ruts are more than 6 inches deep (Photo 2) and in others, they are only 2 inches deep.
Most of the harvest ruts I’ve seen are confined to localized areas within fields. However, there seems to be more fields this spring where deep ruts created by every pass of the combine can be seen (Photo 1).
In one field, the ruts ran up and down a gradual but long slope. In this case, the ruts need to be filled as soon as the soil is suitable to prevent soil erosion from turning them into deep gullies (Photo 3). All ruts deeper than your projected planting depth must be leveled prior to planting for planters and drills to perform properly.
When repairing ruts this spring, the objectives are to fill and level the ruts just enough to facilitate planting operations without causing further soil compaction. Loosening the soil at the bottom of or below the ruts should not be attempted because the tillage tools will need to be operated at greater depths and into soil that is probably too wet. This increases the risk of further soil smearing or compaction to occur. Root growth and crop yields will be reduced in the repaired areas.
Michigan State University Extension recommends secondary tillage implements such as disks, field cultivators, soil finishers and vertical tillage for repairing ruts 2-4 inches deep. For ruts deeper than 4 inches, a chisel plow may be necessary. Always operate the implements as shallow as possible to fill and level the ruts. Multiple passes may be required to achieve the desired degree of leveling.
Perform tillage operations when the soil at or just above the operating depth is dry enough to prevent soil smearing and compaction. Iowa State University agricultural engineer Mark Hanna recommends the following methods for assessing soil moisture conditions:
- Collect a handful of soil from an area between ruts and 2 inches above the operating depth of the tillage tool and form it into a ball. Then throw the ball of soil as if throwing a runner out at first base. If the ball stays mostly intact until it hits the ground, the soil is too wet to till.
- Take a similar soil sample in your hand and squeeze the soil in your fist and use your thumb and forefinger to form a ribbon of soil. If the ribbon extends beyond 2-3 inches before breaking off, the soil is too wet to till.
Remember, your objectives with spring rut repairs are to fill and level the ruts without causing further soil compaction. Attempting to loosen the soil below the ruts increases the potential for further soil smearing and compaction to occur.