Compaction damage will haunt you
Damage from soil compaction can have significant impact on water infiltration, root development and, ultimately, grain yield the following season. It’s generally estimated that yield loss due to soil compaction caused by wheel traffic ranges between 10% to 20% depending on the extent of the compaction.
Over the past decade, the size of Iowa farms has increased, leading to larger and heavier equipment. An axle load from a 12-row combine with full grain tank is estimated at 26 tons per axle and a single-axle fully loaded grain cart is estimated at 22 tons per axle.
Avoiding field conditions prone to soil compaction will likely be something you won’t be able to do this fall. Farmers will try to get grain harvested without further field preharvest yield losses and worsening grain quality. Soil compaction will be worse the wetter the soil conditions are.
Follow these tips
Tips to minimize soil compaction during and after harvest
1. Dedicated travel lanes. Many combine operators use “on-the-go” unloading into a grain cart to speed harvest. In areas that have received excessive rainfall since Sept. 1, farmers may want to consider having dedicated travel lanes for the grain cart. It has been documented that 60% to 80% of soil compaction occurs from the first wheel passes, subsequent field operations account for a much smaller amount of compaction.
2. Don’t run at full capacity. Reduce the axle loads of both the combine and grain carts by not loading them to full capacity. This may not be an attractive option in high-yielding cornfields and where harvest has already been delayed. This is much easier to do in soybean fields where the grain volume is much less than corn. A compromise may be to try and keep axle loads lower in the far reaches of fields and achieve the highest axle loads (full capacity) nearest the end rows where grain will be transported out of the field.
3. Tire size and inflation pressure. Use appropriate tire sizes for the conditions and adjust tire air pressure to match the axle load being carried. Larger tires with lower air pressure provide more surface area, allow for better flotation, and reduce pressure on the soil surface.
4. Concentrate nonharvest activates near field’s exit. While it’s tempting to move semi-trailers and tractors with wagons along the field edge as harvest continues, this practice increases compaction along the end rows.
5. Harvest around the wettest areas. The wettest areas are the most at risk for soil compaction but are also an accident risk that ultimately could lead to longer harvest delays. Additionally, buried equipment may come with large financial penalties. Come back to these areas later in the fall once the soil conditions are drier or have frozen.
6. Avoid or minimize tillage. Hold off tillage operations until soil conditions are drier than field capacity. It’s important to consider soil moisture at the depth of tillage. Tillage in wet conditions results in further compaction and smearing of soil instead of the intended fracturing of the soil. If it’s necessary to cosmetically fill in ruts, use a disk unless soil conditions are dry enough for fracturing of the soil through use of more aggressive implements.
In wet conditions, the best choice farmers can make is to stay away from the field and avoid traffic on wet soil to reduce soil compaction. How you approach fieldwork after a heavy rain event can impact your soil for future growing seasons.
This article was written by Mark Licht and Mahdi Al-Kaisa and was featured in the Corn & Soybean Digest. Mark Licht is an ISU Extension cropping systems agronomist at Ames. Mahdi Al-Kaisi is a professor of agronomy and extension soil and water specialist at Iowa State University.
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