Here is a long awaited update on our current trials. This post will focus on our main cover crop trial at Spindletop that was established in 2014. (We have another cover crop trial in the ground, and a trial looking at weed management in canola. I’ll update you on these trials in a later post, as well as some work we did this summer with chia! (Yes, chia. As in the seed with high omega 3 fatty acids and B vitamins. Also as in ch-ch-ch-chia!)) CYou can read about the history of this main cover crop trial in previous blog posts. This was in soybeans in 2015, and I will update you on the research findings in a post later this winter. But I’ve gotten a lot of emails about when it is too late to plant legumes, so wanted to post some details about this trial and some photos of our stands. We harvested the soybeans on October 6, and planted cover crops the next day. There are four treatments in here—bare soil (we will spray off winter annual weeds), winter annual weeds allowed to grow, oats (50 lbs/acre) sown with crimson clover (20 lbs/acre), and cereal rye (50 lbs/acre) sown with hairy vetch (20 lbs/acre). All cover crops were drilled. We planted a small grain and legume mixture because this field will be in corn in 2016. The legumes will provide some additional nitrogen for this corn—how much will depend on how long we let the covers grow in the spring. Grass and legume mixtures are an example of a well-established mixture that we know a lot about. You can read about the advantages of sowing these together on this SARE site. (BTW, be sure to check out the "links" section of this page!) However, sowing legumes in October is dicey! In Kentucky, we like to seed them by October 1 to ensure they establish sufficiently to survive the winter. We had a moderate frost on October 18 at the farm; so far the legumes look fine. It’s possible (maybe likely) that they were stunted by that frost, but it didn’t kill them. The oats also still look fine, though the frost on November 21 dinged them. In fact, given the warm weather that we’ve had this fall (frost on October 18 notwithstanding), the oats look better this year than they did last year. You can compare photos to blog posts from November and December 2014. Click on the photos below to see a larger version. Again, we expect the oats and maybe the crimson clover to winter kill. Kentucky is right on the edge of where the southern-adapted varieties of crimson clover will over-winter. There has been a variety of crimson clover released by the University of Kentucky that is more winter hardy in this area; it is currently undergoing seed increases and will be commercially available soon. The rye and hairy vetch are likely to survive the winter, assuming we planted them in time! But, we hope that both cover crop mixtures will help suppress winter annual weeds.
We did not do any burndown between soybean harvest and cover crop planting. We already had quite a few winter annuals emerging at this time. Last year’s winter rye cover crop was still helping to suppress these—see these photos showing winter annuals emerging in plots with and without rye. Depending on the situation, growers may need to use a fall burndown. This includes if there is any marestail coming up. We don’t have any fall-emerging marestail in this site. Yet. But, as the cover crops grow, I expect they will outcompete these winter annuals and we will have much less weed seed produced in these plots. We have counts of these in the plots (thank you Matthew and Sara Lawson!!!), and will track them. Check out these photos that show how the rye residue was still suppressing winter annuals almost six months after we killed it.
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AuthorErin Haramoto, University of Kentucky weed science Archives
May 2018
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