You planted cover crops on your prevent plant acres to reduce erosion, compete with weeds, reduce fallow syndrome, retain nutrients in your soil, open the soil up to increase infiltration, and to keep the soil organisms active, excellent! Now the covers are growing and may be wondering what to do with the biomass you’ll get this fall and managing it next spring. This will be dependent on the species you planted as well as your crop in 2020. Let’s start with the easy one, if you’re planting soybeans next year, management of your cover crop is very easy, soybeans grow just fine with residue. If your cover crop will overwinter, plant your soybeans green and terminate the covers after planting to make planting with high residue easier. If you terminate the covers before planting, you may have issues with the residue wrapping and having difficulty with seed placement-it’s easiest to plant into standing covers.
If you’re growing corn next year and you haven’t been using soil health practices for long, it is recommended to kill a winter hardy cover crop about 2 weeks before planting to reduce potential pest issues. If your soil biology is robust, we don’t see issues planting corn green and terminating covers after planting.
If you have large amounts of biomass from grass/grain species, you’ll want to front load your nitrogen so your corn gets it while the covers are decomposing-the longer the residue takes to decompose, the longer the nitrogen will be tied up. Using species that fix nitrogen and/or break down faster (broadleaves) will help break down the high carbon residues (grasses/grains) to release the nitrogen faster. It’s all about managing your Carbon to Nitrogen ratio!
When planting into covers-dead or alive-your most important piece of equipment is your planter (as well as your combine) but getting the settings right so you’re getting proper seed placement and closing will be what to focus on in the spring.
The covers will be working this fall, winter, and spring to improve your soils, working your fields in the spring may seem tempting to manage the residue but that will undo most of the benefits your cover crops are providing you. We’ll be breaking the soil structure which will increase compaction, reduce infiltration, reduce oxygen flow, burn carbon (organic matter), disrupt soil biology so they have to start over building their communities instead of benefiting crops, and can lead to issues with residue and root balls.
Tilling covers such as annual or cereal rye, sorghum sudan, and other high biomass species can make planting very frustrating-the covers may replant themselves and act like a tumor and go nuts and seed placement will be difficult.
Grazing or haying covers can be a good option for biomass management. No livestock? No problem! Check out the Cropland Grazing Exchange to find others to graze or get forage http://www2.mda.state.mn.us/webapp/GrazingExchange/MDAHome.html
Talk with our farmer mentors, neighbors, or stop into your local conservation office for more information!
NRCS: https://www.nrcs.usda.gov/wps/portal/nrcs/mn/contact/local/
SWCD: https://www.maswcd.org/SWCDs_On_The_Web/swcds_on_the_web.htm