Protect the soil that took thousands of years to form.
Soils take thousands of years to form. While erosion is a natural process, the amount of erosion that can occur and still allow soils to maintain their viability is quite small. Production practices need to minimize the potential for excessive erosion.
Erosion of soils is an inherent occurrence, but it happens at such a slow rate in the natural world that soils can maintain their productivity or build up over the years.
Most Illinois soils are incredibly productive for growing a multitude of crops and other plants. On the most productive and resilient soils, they can erode up to 5 tons of soil per acre per year and still maintain their productivity. While this sounds like a tremendous loss, it would not be noticeable to the eye. If you put your thumb and finger as close as possible to each other without touching, that would be the thickness of soil loss.
On less productive soils, the erosion of even 1 ton per acre per year may be considered excessive.
Excessive erosion causes loss of topsoil (the A horizon), which is the most important part of soil for plant growth. This layer contains soil organic matter, good structure, and other vital biological components.
Leaving the soil surface without cover increases the chance of too much erosion occurring. This is especially true when bare soil is allowing on sloping ground. Small gullies are areas where hundreds or even thousands of tons of soil are lost in a concentrated spot.
Controlling Excessive Erosion
Leaving residue on the surface instead of having bare soil greatly decreases the chance of excessive erosion. Residue can be remains of a previous year’s crop, mulch, or a thin layer of applied compost. Living plants in the form of cover crops can also reduce erosion rates, especially cover crops that overwinter.
Tillage and Erosion
Tilling soil increases erosion rates by allowing precipitation to wash away more soil. In addition, tillage decreases the size of soil crumbs (structure), which also allows more soil to erode, not to mention increasing the rate of soil organic matter decomposition. When tillage is necessary, it should be kept to the minimum needed for crop or plant growth.
Erosion and Extreme Precipitation
Precipitation trends show heavy events have become more frequent, and these are projected to become more common. These events bring intense precipitation over a short period of time. With this trend being expected to continue and potentially increase, what may have been a good management practice to control erosion may no longer be enough to keep gullies from forming. Areas where concentrated water flow occurs should be examined to see if additional control measures are needed.