Wet harvest conditions may result in soil compaction
The highly unusual wetter than average fall season had many of us harvesting fall crops in very wet soil moisture conditions. This resulted in leaving wheel tracks and ruts across the fields. Even where we didn’t rut up the field we may have compacted the soil to the point to where plant rooting and water infiltration will be affected. The question now is what we do to correct some of these issues we created.
If there are significant ruts across the field there may be no choice but to do at least some tillage to smooth out those areas just to facilitate future field operations. Probably not a big deal to those that typically do some tillage in their cropping system. But for us no-tillers we may have consider doing some spot tillage just to get the field smoothed back out. I would run the tillage implement just deep enough to fill in and smooth out the ruts. The type of implement you use may be somewhat determined to what is available but a vertical tillage tool may work the best. By design they are made to work shallow and smooth the ground.
That may take care of the ruts, but we still may have a compaction issue that was caused by heavy combine, grain cart and tractor wheel loads. But before we get to anxious about doing something we need to really determine how serious the compaction is. A soil penetrometer that measures the resistance, in pounds per square inch, as it is pushed into the soil works well to determine the amount and depth of the compaction. Another option would be to use a soil moisture probe and determine resistance by feel as the probe is pushed through the soil. There needs to be adequate soil moisture when using these tools to avoid getting false readings.
If we do have compaction that needs to be addressed there some options to correct it. If the compaction is not to severe and is shallow it may be best to let Mother Nature take care of itself. Through the winter the wet soil will freeze and thaw multiple times which will help loosen the soil to the depth that it freezes. In heavier clay soils the shrink-swell action when the soil wets and dries will also help with breaking up compaction layers.
If the compaction is significant, planting a cover crop, especially in fallow cropping systems, may be a good choice. Species with deep tap roots and robust fibrous roots should be a significant part of the seed mix. With the wetter than average conditions there should be sufficient moisture to get a cover crop established early next spring. The wetter soils will also help the plant roots penetrate through the compacted areas. After the cover crop is terminated and plant roots decay, channels will be left behind where new plant roots and soil water can follow through the compacted areas. The cover crop needs to be terminated timely to prevent excessive soil moisture use that may be needed for the next cash crop.
Subsoiling, or ripping, the field with a low disturbance ripper that leaves the crop residue on soil surface in place may also be something to consider. But before we go to that extreme we need to think about the cost, the amount of time it is going to take and what potential benefit we are going to gain. University research in the corn belt suggest that ripping done at the proper time, proper soil moisture level, and at the correct depth and speed can break up compaction layers. But typically, that benefit is short lived and after one or two tillage operations the soil consolidates and gets compacted again at the tillage depth.
For more information about this or other soil health practices you can contact me at [email protected] or any local NRCS office.
