We applied a burn-down herbicide application on May 8 to terminate the cover crops and control other weeds. On May 9 we planted a group 2.7 soybean. This included planting with a drill into standing cereal rye, wheat and annual ryegrass. This has become a fairly standard practice among experienced cover croppers. Sometimes the cover crops are controlled after planting with an early post application. The standing cover crops do not usually created a problem planting into – you just need to make sure your planter is set up correctly. As the cover decomposes it creates a mulch layer which can be a big help keeping soils cooler and retaining moisture during hot, dry years.
Keep in mind that with corn you can have a problem with a high carbon to nitrogen ratio creating a deficiency situation early in the growing season, particularly with cereal rye, but this is not an issue with soybeans.
Early May was a very dry period for this part of Indiana. I took some pictures on May 25 (not included). The beans were up but barely and I was a little worried about complete termination. We received some rain last week, about 1.5″, and things changed completely with good elimination of the cover crops and what looks like a nice stand of soybeans.
Hopefully with the shorter season beans and an early May planting we’ll be able to get our fall covers in place in a more timely manner than we’ve been able to do the last 2 years. For the start of the growing season things look very good.
We had a great day March 30 for our Cover Crops Workshop and Field Day. We had 32 in attendance, 24 farmers and while we had to work around thunderstorms we did find a window where we could go out and look over the plots – unfortunately the soil pits had filled up with water from the rains.
The morning program included a presentation from Corey Lacey. Corey is a Purdue University graduate student working with Dr, Shalamar Armstrong on whether nitrogen taken up and stored in cover crops is available the following crop year. Research is ongoing with this but the ultimate answer is, “some is available but it will take more research to determine exactly how much.” Hopefully at some point there will be enough research where this impact can be determined more precisely. We also discussed termination, herbicide carryover, and how this can impact cover crop selection.
As there was a morning window when it wasn’t raining, we took advantage of the situation to head out to the plots. NRCS Soil Scientist Mike Wigginton discussed what he found at the plots and in the soil pits with attendees.
The pits had filled up with water from a combination of water infiltration (it’s been a wet spring here) and rain the night before so these pictures are from the day before when we dug the pits. I’m focusing on root depth because while top growth is nice to look at and offers some benefits, beneath the soil surface is where things are really happening. It may be difficult to see the roots themselves in the pictures so look for the golf tees. Keep in mind that cover crop roots:
Increase water holding capacity and infiltration by forming channels
Provide a pathway for crop roots to travel, allowing more access to water during dry periods
Provide habitat for soil microbes
Through decomposition improve soil organic matter and increase nutrient availability
Help break up soil compaction layers
In the case of legumes provide nitrogen fixation
The cereal rye plot had some good spring growth going on and there were very few weeds present. Mike found roots to 32 inches deep, down to the glacial till layer. As you can see from the picture, the pit started to fill with water running right above that dense till layer as soon as it was dug.
The second strip was planted to barley, rape and hairy vetch. The growth wasn’t quite as lush as the cereal rye strip but it was coming. Mike found living roots in the soil pit down to 26 inches, right above the glacial till layer.
The final strip with spring growth was planted to annual ryegrass, hairy vetch, crimson clover and rape. The rape and vetch were just getting going, the clover was coming in well but was still fairly small and the annual ryegrass had a lot of growth. Mike found a lot of roots in this pit, down to 36″.
One of the interesting “finds” was that even though short, crimson clover had already started nodulation meaning it was starting to add nitrogen to the soil. I have no idea if this will be a significant amount for the corn we’ll be planting but it will be something to look for this fall during harvest (as I type this we are planning to terminate on April 17 if the weather holds).
We always plant one strip to oats and tillage radish because this is a great mix for farmers just getting started with cover crops. Oats and radish both winter kill so it takes away any termination concerns. While you lose some benefit because of no spring growth, it still provides quite a bit. We did not dig deep pits for this or our “check” strip with no cover crops as we would not have found living roots. Keep in mind that last fall we planted the strips on October 18, well past the recommended September 15 date for both of these, based on the Midwest Cover Crops Council Selector Tool. The oats and radish did come up last fall but were pretty small. However even with this situation, the weed population was significantly less than in the straight no-till plots. The main weeds we found were dandelion, chickweed and purple deadnettle. Evidently, even though we planted later than recommended, the cover crops inhibited the germination of the winter annual weeds.
While we are not arguing that planting cover crops means you can do without weed control the next year (is anyone arguing this?) since purple deadnettle is a host for soybean cyst nematode (SCN), this mix, even planted late, may provide an advantage when planted ahead of soybeans.
While our plots are for demonstration and education, not research, I did find myself thinking it may be worth doing some weed counts in the future.
Following the plot tour we had a farmer panel featuring Zach Cain, a Montgomery County farmer, Clint Orr, a Clinton County farmers and Justin Mohler, who farms in Boone and Clinton counties. We had a good discussion. Much of it was on specifics such as planting equipment and setup, mixes that did and didn’t work, termination issues – really the nitty-gritty of cover crops.
This was a good day. I hope everyone learned a lot. On the evaluations several farmers said they intended to start planting cover crops and others mentioned new mixes they would try. Thank you to Boone County Farm Bureau for sponsoring lunch and, as always, to the many farmers, agribusinesses, lenders, etc., who have assisted with this project. I look forward to our next field day, sometime this fall.
Our next Cover Crops Field Day Will be held Thursday, March 30 from 8:30 a.m. to around 3:15 p.m. The program will be held in the Annex Building at the Boone County 4-H Fairgrounds, 1300 E 100 S, Lebanon, IN.
Speakers for the day include Mike Wigginton from the Natural Resources Conservation Service, Corey Lacey from Purdue Agronomy, Brian Daggy from Boone County SWCD, Curt Emanuel from Boone County Extension and a farmer panel featuring Bruce Guernsey, Zach King and Clint Orr. Topics will include a discussion of the financial benefits of cover crop, species selection, herbicide management, how cover crops can impact available soil nitrogen, and touring cover crop plots to discuss production systems and impacts on soil health.
The program has been approved as a Private Applicator Recertification Program (PARP). Lunch, sponsored by the Boone County Farm Bureau, will be provided. There is no cost except for a $10 fee for those seeking pesticide credit. Pre-registration is requested to help with meal planning. To register call the Boone County SWCD at 765-482-6355, ext, 134 or e-mail Sheryl Vaughn at the SWCD. Much of the program will take place outside at the field plots so participants should dress accordingly.
One of the most important issues related to cover crops is termination. Cover crops are great – until they compete with cash crops for nutrients, water, sunlight, space, etc. In a normal field situation a farmer will plant one cover crop or at least a single mix. In our case we had four different cover crop “treatments” to contend with. Despite this, we didn’t have any trouble terminating the cover crops in the entire area with a single herbicide mix.
The herbicide application we used was a burn-down of 1.5 lbs active ingredient(AI) glyphosate with 1 oz Sharpen (saflufenacil) sprayed/broadcast on April 16. There is little residual activity with this mix however, as you can see from the picture, it was very effective in terminating the cover crops as well as taking care of what weeds were present – which weren’t a lot, from what I saw, mainly chickweed and dandelion though I didn’t scout the field after the March 24 field day.
In 2014, the last time this field was planted in soybeans it had quite a bit of marestail (sometimes called horseweed, Latin name Conyza canadensis). In central Indiana marestail is often glyphosate-resistant and even when it isn’t, control becomes difficult once it gets above 6 inches tall. For this reason we will be using a Liberty variety of soybeans once it becomes dry enough to plant.
It’s been cold and wet here for the past couple of weeks but we were fortunate to have some warm weather right after the burn-down which certainly helped with that application – as a general rule, daytime temperatures above 50 degrees for several days after herbicide applications increase the effectiveness. According to the National Weather Service daily highs in Indianapolis were at or above 80 degrees on April 17 through 20 (and 77 on the 16th), nearly ideal conditions. Hopefully things will dry up so we can provide a planting update in the near future.