With all the rain we've had this week I thought today would be a good time to talk about cover crops, organic matter and preventing erosion. We've had a pounding rain for two days this week, and I'm glad we got as much ground covered as we do. The very nature of how we use the land for the production of crops leads to potential erosion issues every time we have heavy rains. A "gully washer" can wreak havoc with topsoils in the middle of the summer. A thundershower often has torrential but brief downpours which also can lead to significant erosion. Sometimes dry soils will resist a heavy and fast application of water and that's when erosion can happen quickly and without warning.
So, what's the big deal about erosion? Erosion takes place in nature all by itself. Ever wonder why the rockiest soil is on the ridge tops while the deepest soils are in the valleys? The rain has washed the soil down off the hill for hundreds or thousands of years. Small soil particles move easier than large ones so the rocks are left and the soil is moved. This moving usually moves the same amount of materials that is made up new each year.
In an agricultural setting erosion speeds the loss of topsoil at an alarming rate. Topsoil is necessary for plant growth; without it you have nothing. It takes nature 100 years to deposit an inch of topsoil and that can be lost in one season or less. Agriculture disturbs the organic materials left on the surface by living, dying and rotting plant materials and exposes it to the ravages of the weather. A heavy rain is all it takes to wash the soil away. Land must be managed to achieve maximum crop yields while keeping and improving the makeup of our precious topsoil.
Crop land often removes plant roots that hold the soil in place. A crop of grass holds soil much better than a crop of carrots, but there must be middle ground somewhere. We need our crops but we need to preserve our soils to grow them; a circle indeed; one step relying on the others. So, in order to prevent losing our topsoil and preserving it for future generations, we need to develop a plan to enrich, preserve and maintain biological diversity in our soils.
Ways to prevent erosion:
- Avoid any more tillage than is needed. A neatly rototilled garden looks neat but a garden with plant material, dead or alive, is better for the soil. No recreational rototilling; all this tilling breaks up soil structure and leads to erosion.
- Leave no space bare. If you're not going to plant it, sow some cover crop seed that will hold and enrich the soil naturally and prevent erosion if even on such a small scale. Toss some wildflower mix on it as well.
- If planting a cover crop is not possible, then rough up the surface of the plot to stop the flow of water. This will make the water soak into the ground and not go racing down the hill taking soil with it.
- Plan your growing area to the contour of the land. No rows up and down the hill - ever. No planting where it's really steep unless a system to stop erosion is in place - like a bark mulch on berries.
- Leave crop residue in place. At the end of the season, leave crop wastes (now called crop residues) in place. No need to move those vines or remove the sunflower stalks. Leave the unharvested crops where they are; it's not important to remove all crop residues. Leave organic mulches in place as well. Add some organic matter in the fall; leaves, mulch hay, vegetable trimmings and bedding from the barn. I run over the garden with an old bedspring towed behind my four wheeler to level the surface without removing any surface residue.
Simple, common sense ways to keep our soils where they should be. Don't think that because you have a small plot that erosion control isn't important; it is. Everyone who works the soil shares the responsibility to preserve it for the generations that are yet to come.
Until next week, Brian