Cover crops benefit plants, soil, waterways

Whether down in a soil pit or presenting in front of a screen, Ray Weil is clear that growing cover crops isn’t just a nice thing to do. In his state of Maryland, farmers are keeping tons of sediment and nutrients out of the Chesapeake Bay and on the fields where they belong by using cover crops.

About 90 Bartholomew County farmers and natural resource professionals were on hand at Sudan Farms last month to take it all in while listening to the professor of environmental science and technology at the University of Maryland.

It shouldn’t come as startling news that well-selected cover crops can provide some advantages. Writings as deep into history as those by Virgil (70 to 19 B.C.) describe the use of alfalfa, clovers and lupine for increased wheat yields. So what are those advantages? According to Weil and others, cover crops can:

Help to keep soil particles in place, reducing soil loss through erosion

Bring nutrients closer to the surface, where they can be used by the crop

Reduce soil compaction, making no-till practices more accessible

Improve the soil structure

Reduce weed seed germination

Capture nitrogen, keeping it on the field where it can be used by crops

Improve a crop’s resilience to drought, by holding on to soil moisture

Improve a soil’s drainage through improved pore space

If the last two items in this bullet list seem contradictory, it helps to see the cover crop as optimizing on a soil’s ability to shed and hold water, mostly through organic matter left behind. Better yet, the watershed by a field with a cover crop in its cropping system is likely to carry less sediment.

As for local data, the numbers from the Flatrock-Hawcreek Watershed Project are telling. According to Jenny Whiteside of the Bartholomew County Soil and Water Conservation District, over the three-year project period, the following quantities of material were kept out of those waterways, largely through the use of cover crops:

5,072 tons of sediment

13,132 pounds of nitrogen

4,498 pounds of phosphorus

So you can see that planting cover crops isn’t just a nice thing to do. It keeps soil, water and nutrients in place, and optimizes on several other soil properties.

But why do I want you to know this? Because agricultural practices can be easily misunderstood. For instance, what would be your first guess if you saw a plane making pass after pass over a field near you? It would be understandable if you guessed “pesticide application,” which might sometimes be the case.

Consider, when you see that crop duster that it may be flying on a cover crop. Yup, seeds. This time of year, some farms are putting cover crop seeds directly over a maturing corn crop. Aerial application is also used when a field is too wet and the weight of tractor and planter would bring on compaction.

Another opportunity for misunderstanding comes when fields, which neighbors may have gotten used to looking tilled and clean, look a bit weedy because that cover crop may not have the tidy look of bare soil, or of a crop growing in rows. The look (and smell) of a field of daikon radish may be a small price to pay for tons of sediment and nutrients staying in place.

It’s important to remember that cropping systems can evolve rapidly, or it might seem that way to those of us who don’t live farming every day. The annual succession of activity, while still driven by the growing season, might include some new and different steps.

For more information

For more on cover crops, go online at ctic.purdue.edu/Cover%20Crops/