Farmers are eager to harvest soybeans and corn but the fields are very soggy in much of Ohio. The danger of causing soil compaction is therefore high. Let’s look at ways to increase the resilience of the soil to compaction, to avoid compaction, and ways to alleviate compaction.
Resilience is a term used by ecologists to describe the ability of an ecosystem to resist perturbation or disturbance by resisting damage and recovering rapidly. Soil can be made to resist compaction by eliminating tillage, increasing organic matter content and maintaining a living root system in the soil for as much time as possible. Any long-term no-till farmer will testify to the fact that tires do not sink as deep as in tilled soil. Soil that was tilled this spring or even in last year’s spring, will be more susceptible to compaction than a soil that has been in no-till continuously.
Increasing organic matter content will also increase the resistance of the soil to compaction, because the spongy humus maintains porosity and also increases aggregate stability.
Finally, a living root system at time of traffic would increase the resistance of the soil to compaction. While it is uncommon to see living root systems at harvest time, some exciting work is being done at Penn State University with establishment of cover crops into standing corn or soybean, combined in one pass with herbicide application and side-dressing. Resilience also includes the concept of kicking back after disturbance. To make soil kick back from the effects of compaction, it is important to try to establish a cover crop after harvest. The roots of the cover crop will help alleviate compaction that has been caused. It is also a practice that helps increase biological activity in the soil – the mycorrhyzae and bacteria growing in the rhizosphere of cover crops produce glomalin and other organic substances that improve aggregation of the soil. If manure is available to give the cover crop a boost and supply additional food for soil microbes that will also be helpful.
It should also be noted that without soil disturbance and leaving soil covered with mulch smaller and larger organisms such as nightcrawlers will be much more prevalent and active than if soil is tilled and left bare. Therefore, fall moldboard plowing should be avoided especially, and even chisel plowing in the fall will reduce the activity of these organisms that can help soil kick back from the effects of compaction while also improving drainage of the soil.