Planting mixed species of cover crops is the new normal.
Farmers can easily understand the theory of mimicking nature upon which this concept is based. But more importantly, they are seeing tangible results of achieving more benefits without additional costs.
Some farmers are taking it to a new level by strategically adding cover crops to some cash crops. This may be a stretch for most farmers, and it does have its limitations, but planting a cover crop with a cash crop is gaining momentum.
Where it all started
I was introduced to this concept while on a speaking tour in France during the spring of 2010. They were using fava beans, spring peas and flax planted with oilseed rape, commonly known as canola. The fields were test plots with various cover crop mixes planted with the cash crop to see which ones worked best.
In the context of oilseed rape or other winter annual cash crops, the goal is to grow beneficial cover crop species that will winter-kill, leaving the cash crop to grow by itself in the spring. In some situations, herbicides can be used to accomplish the same thing. I saw this being tested this past spring in Belgium on a rather large scale by Bayer Crop Science. The fact that the largest herbicide manufacturer in the world was testing herbicides with companion crops indicates strong validity to this concept.
In addition, large processors in Europe have been providing premixed oilseed rape to farmers with specific cover crops!
Legumes provide nitrogen in the fall along with potential for some nitrogen in the spring. With the addition of grass-type cover crops like spring oats that will winter-kill, weed control is also enhanced. The biological effects of multiple species of plants provides a synergy we don’t fully understand yet. Seeding rates need to be such that the added plants don’t interfere with the cash crop’s growth.
It does take some educated guessing or calibration of a planter to get the overall seeding rate just right.
Aside from basic synergistic benefits, these practices can positively affect a farmer’s bottom line.
For one thing, less nitrogen is needed due to the use of legumes that convert nitrogen from the atmosphere. Herbicides can be eliminated due to increased fall canopy of the mix, which shades out winter annual weeds. Insect pressure is almost always less, which results in less insect damage or the use of insecticides.
All these factors can add up to three fewer application trips across the fields, further cutting costs. And the yields are right up there with historical averages.
The fact that this practice is so widespread in Europe, and is now gaining traction around the world, further indicates its merit.
There is very little canola grown in the U.S. However, we can apply this principle to more popular cash crops.
Some farmers have grown winter wheat with 3 pounds of radishes added and have seen a yield increase of up to 6 bushels per acre. This past summer in Kansas, I saw some experimental plots of cash crop milo that included mung beans and several other species, including zinnias that attract beneficial insects that eat the problematic sugarcane aphids. By harvesting the taller milo with a row-type head, the hope was that most of the other mature cover crop seed would not go into the combine.
The coach’s closer
I’ve successfully applied this concept on my farm here in southeast Pennsylvania for the past three years by utilizing the European model with a cash crop of oilseed rape. I also grow hairy vetch, winter peas and oilseed rape that are harvested together and then cleaned and separated to be sold as cover crops.
How might you be able to use companion cropping on your farm?
Groff is a cover crop pioneer and innovator who farms in the Chesapeake Bay Watershed. Check out his website, covercropcoaching.com.