Apologies for not posting recently. With spring 2018 coming up it seems as if a review of 2017 is in order.
This was a difficult spring in Central Indiana. We first terminated the cover crops in mid-April and then it turned cold and wet so we made an additional herbicide application in late May. We were finally able to plant corn on June 2, 2017. The growing season got off to an OK start with decent rains and fairly warm temperatures. Later it turned dry with very little rain in August. The rains returned in early September.
I went out and looked at the field in late July and there were some things worth mentioning. Keep in mind that for this project we plant cover crops in 40-foot wide strips. I wouldn’t say that corn looked better or worse in a strip but it did look like some strips were further along. We planted the entire field the same day, using the same equipment and the same settings however on July 31 some strips were well along in silking while the Oats and tillage radish strip in particular had just started to tassel and plants were about a foot shorter.
This continued through the growing season. I went into the field on August 31 to look at maturity and black layer formation (maturity) was just starting in two strips while in the no-till and Oats/Tillage Radish strips the corn was in early dent – just leaving dough stage. If I’d had no other information to go on I’d have said those strips were planted 10-14 days later than the others. Again, the corn didn’t look better or worse, just at different maturity stages. I can’t begin to reach any conclusions about that.
The plots were harvested on October 17. There were some yield differences between strips, much more significant than we saw the previous year with soybeans. Our thoughts are that because some corn matured later it was able to take advantage of September rains after a very dry August. The overall yield was 171.4 bushels which we were fairly happy with. It is also interesting that one of the cereal rye strips had a lower yield which is not surprising – planting corn into cereal rye can be a problem due to Nitrogen availability. However the other one did not.
This continues to be a learning experience for us and while field observations were interesting it’s hard to see anything that could be considered actionable. As with 2016, yields were comparable in the strips planted to cover crops compared with those in straight no-till, with the exception of the two northernmost strips.
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.
Curt Emanuel, Extension Educator, Purdue Extension – Boone County
On Tuesday, September 29 we planted three of the five cover crop “treatments” we’ll be incorporating into the project. Those treatments are:
Annual Ryegrass-Oats-Crimson Clover
Tillage (Oilseed) Radish-Oats
Late-planted (about November 1) Cereal Rye
Rain interrupted us before we could get the Radish-Oats mix planted and we’ll be planting some cereal rye later. Hopefully we’ll get the oats and radish in the ground by the end of this week. We performed no tillage and made no herbicide applications before planting. All of the cover crops are planted in 40′ strips and we did a replication (planted each treatment in two areas of the field). I’ll load a map in the near future.
This will make for an interesting educational opportunity. It’s pretty late to be planting radish so we may not get much top growth but it may surprise people when we dig pits next spring to see how much root growth went on underground. It really is amazing to see plots where very little vegetation came up where they have root systems two or three feet deep. It’s a nice example of how much good these cover crops may be doing even when we don’t see evidence of it from the surface.
EDIT: Oats and radish were planted by Brian on October 1, 2015.