A living root: Ag science reveals benefits of cover crops
Planting a cover crop on fields between growing seasons is becoming more appealing to ag producers of late, particularly those who own livestock. Ryan Buetow is the area extension cropping systems specialist at the Dickinson Research Extension Ce...
Planting a cover crop on fields between growing seasons is becoming more appealing to ag producers of late, particularly those who own livestock.
Ryan Buetow is the area extension cropping systems specialist at the Dickinson Research Extension Center and he hosted an open house earlier this week to present the further benefits of keeping roots in the soil.
"The goal of the cover crop is to keep the ground covered so you can build your soil aggregation and get carbon into the soil," Buetow said. "You want to match it to your goals."
Enriching the soil can come in several ways, from creating an environment for pollinators like bees to thrive in to breaking up the soil and leaving large enough holes for water to saturate it easier.
One particular way that the extension center has been using cover crop is to perform a function called "nitrogen fixation." This, in essence, utilizes biological functions to create a means for plant and soil lifeforms to receive nutrients from the earth's abundant nitrogen atmosphere. By itself, nitrogen isn't something a plant can use-but on the roots of some legumes, like the peas nestled into the earth of the fields just north of CHI St. Alexius Hospital in Dickinson, a remarkable process allows this gas to be converted into sustenance for the soil.
"These nodules on the root ... that's a bacterial colony," Buetow said, unearthing a plant to show off its root system, where pale, fleshy blobs cling. It doesn't take much to pry them open, revealing a red pool within. "You see how it's red in there? That's something called leghemoglobin, which is similar to the hemoglobin in our blood ... that allows it to be an anaerobic (oxygen-free) environment. There's no oxygen and those bacteria need that environment to do their job ... the plant takes that nitrogen, turns it into a form the plant can use, and in return the bacteria gets energy."
The key to cover crops is to pick the best one for the purpose you want fulfilled.
"Sometimes the benefits are more underground than above ground," Buetow said. "Each plant has its own thing it specializes in."
If you want to break up your soil compaction layers, plant some radishes or turnips, which leave behind large holes that can bring water deeper into thirsting soil. Good pollinators would be the likes of sunflowers or phacelia, Buetow recommended.
It's important to be mindful of the consequences of picking the wrong cover crops too-if you plant cereal grains in proximity to wheat or winter wheat plants, for instance, you'll end up playing host to a type of mite that can spread a virus called wheat streak mosaic that can wipe out a whole harvest.
Another issue is the fact that a lack of moisture can make it tough to be able to plant cover crops period.
"We got lucky in August that after we planted our cover crops we got some moisture ... but you can't plan for a drought. You gotta hope you get rain," Buetow said, though he emphasized that something is better than nothing when it comes to having cover crops in the field.
"Whether it is leaving residue out in the field or planting cover crops after harvest ... you gotta make sure you're protecting your soil and keeping a living root out there."
Some resources to help farmers pick their best possible cover crops include the Midwest Cover Crops Field Guide, which can be found online here: https://ag.purdue.edu/agry/dtc/pages/ccfg.aspx and this NDSU publication freely available here: https://www.ag.ndsu.edu/plantsciences/research/forages/docs/Selecting_Co... .