By Josh Britton
Doorways to diversity
If you are interested in getting increased diversity and complex mixes of cover crops into your rotation, you may need to look closely to find the appropriate window for seeding. Many cover crop species, including clovers, millets, brassicas and radishes must be seeded by September or even July for successful establishment.
Typically, this means seeding them behind a small grain harvest such as wheat or rye. Without these species in your crop rotation, there are few windows to bring in some of the unique cover crops to help address compaction, scavenge nutrients and build organic matter.
If you are looking for an easier entryway to cover crops in a corn/soybean rotation, consider identifying the window to plant wheat or rye after fall harvest.
Temperature troubles
When planting late season cover crops, rye becomes the go-to option as it has the latest seeding deadline, according to NRCS specifications (Nov. 1). However, farmers planting cover crops outside of a cost-share program may be inclined to push that seeding date even later, especially in years such as 2017, when crops were late to come off across much of the region.
Soil temperature is a key factor in successful seed germination and for our late season cover crops such as wheat and rye, the minimum soil temperature required for germination is around 40 F.
Using data from the Ohio Agricultural Research and Development Center in Wooster, we can look at the impact planting date would have had during the past fall. For instance, if the cover crop was planted on Oct. 15, the next 26 days would have stayed above 40 F.
Soil temperatures
If the cover crop was seeded just two weeks later on the first of November, there are only eight days until the soil temperature drops below 40 F. Finally, if harvest was delayed and cover crops got planted after the seed deadline and were planted on Nov. 30, daily low soil temperatures would have remained below 40 F for the remainder of the year, with the average soil temperature only climbing above 40 F on two days in December.
Short-season success
One option to explore to expand the window for planting late season cover crops is to look at an earlier maturing variety when selecting corn or soybean seed to plant this spring.
The 2017 Ohio Soybean Performance Trials examined 159 soybean varieties, with relative maturities from 2.3 to 3.9, at their Northern location in Sandusky County. The results on that farm showed no direct relationship between average yield and the relative maturity of the variety.
What changes can you make to make cover crops a priority on your farm? Do you need additional time to ensure you are able to get those cover crops planted?
Consider talking to your agronomist about selecting an earlier maturing variety. Do you need to find a window for summer cover crops?
Think about adding a small grain to your rotation. What other erosion or water quality issues need to be addressed on your farm? The winter is a great opportunity to talk to your local soil and water conservation district and begin the process of developing a conservation plan.
