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An Excellent Cover Crop Mix Ahead of Corn
The mix pictured above is Nutribuilder Mix. It’s a three way mix of annual ryegrass, clover, and radishes.
This field was planted on August 18 at 25 pounds per acre. The included pictures were taken on October 30. The plan is to plant this field into corn next year.
The growth in this field shows the importance of a timely planting date. This is especially important for the radishes, since they will winterkill – and the farmer will want maximum benefit from them before they die.
Benefits
Each component in this mix will enhance the performance of the soil and improve the productivity of the following year’s crop. And of course, the long-term benefits associated with the ongoing use of cover crops are hard to quantify.
But what are some specific things to expect from each of these components?
Annual ryegrass
Annual ryegrass provides one of the best cost-to-benefit ratios of any cover crop, maybe the best. It’s inexpensive, versatile in application (aerial, broadcast, drill), and provides tremendous value to the soil. Annual ryegrass breaks up compaction, allowing better water infiltration. The depth of the roots provide access to parts of the soil previously unavailable to the cash crop. The fibrous root system near the soil surface helps prevent erosion. Annual ryegrass is an excellent scavenger of leftover nutrients, holding them for use later in the growing season.
Crimson clover
Crimson clover is an excellent choice for building nutrition into the soil. If you’re looking to build nitrogen for your cash crop, crimson clover provides that service. Since it will survive the winter, it will provide biomass as well. The crimson clover will also help the annual ryegrass and radishes to grow bigger and provide more benefit to the soil as well, as demonstrated by this video.
Radish
Cover crop radishes have been the super stars of the cover crop world. Their benefits have been noted over the years. They:
- scavenge nutrients from the soil (especially nitrogen).
- penetrate the soil, therefore reducing compaction.
- enhance soil percolation and aeration.
- provide an excellent environment for earthworms.
- provide deer and cattle an excellent wintertime feed.
- die in the winter.
Conclusion
Taking all of this information into consideration, this type of mix is an excellent choice to plant in the fall before planting corn the following spring. Keep in mind that only the radish will winterkill, so you will need a plan to terminate both the annual ryegrass and the crimson clover.
Austrian Winter Peas
Austrian Winter Peas are a good cover crop for producing nitrogen. These peas have better cold tolerance than Canadian Field Peas yet still grow well when planted after wheat or other summer annuals. It’s preferred to plant them in August after the hottest days are normally past. Below I list the advantages and disadvantages of Austrian Winter Peas.
Advantages
- Produces 60-120#/acre N
- Generally Winterkills
- Easy to kill with herbicides
- Mixes very well with Oilseed Radish
- Relatively inexpensive to use as a cover crop
Disadvantages
- Best to be planted 1/2″ or so
- Aerial application provides challenges for stand establishment- but has worked!
- Generally Winterkills
- Needs 5-6 weeks growth for best results
- Only one grazing/harvest can be expected
Cover Crop Selection – What to plant after wheat or other cereal grains?
I was in a meeting yesterday and the gentlemen from SWCD asked me:
“What should we recommend for our producers to plant as a cover crop after the wheat comes off?”
After running through a number of scenarios I determined that I’d better make sure I don’t confuse folks with too many ideas. So, here are a few scenarios that I hope you find useful.
If you want to scavenge Nitrogen and other nutrients, then a good choice would be Oats and Radishes mixed together. This mix generally should be planted at 1 1/2 bu Oats and 2-5# of Oilseed radish/acre. This mix also requires manure or around 40# N applied for it to be the ideal mix for this situation. This mixture will die in the winter and provide excellent winter annual weed control. Best planting time is Mid August…so you have plenty of time to get weeds killed and manure applied.
If you have livestock to feed, other great nutrient scavengers to plant after wheat are Sudangrass, Pearl Millet, or Sorghum-Sudangrass. These summer annual grasses require 100+# of N or equivalent manure. Tonnage of 4 1/2 tons Dry matter/acre have been common in northern Indiana following wheat the past three years. These grasses are excellent soil builders as well. Mycorrhizae fungus find the roots of these plants a very good place to multiply and build soil structure.
If you want to produce nitrogen and also scavenge nutrients as well, then an excellent choice will be Austrian Winter Peas mixed with Oilseed Radish . This mixture works very well without the addition of additional nitrogen. Count on the peas to deliver 60-120# of N and the oilseed radishes to keep most all of it in the top soil root zone. This mixture does a great job of controlling weeds. The radishes will die in the winter and the peas will “probably” die too…depending on your location, planting time of the mixture, and snow cover. If they overwinter they are easily killed in the spring.
If you are looking mainly for nitrogen production with a species that will winterkill, then choose cowpeas. The past few years cowpeas have been very expensive to plant. Be sure to check pricing and also be sure to inoculate the seed at planting time. Sow 60-100#/acre of cowpeas.
If you want the nitrogen production with a crop that will overwinter, then crimson clover is a top choice. Excellent new varieties have come on the market the past few years. Be sure to inoculate this seed as well. Sow 20-25#/acre of crimson clover.
There are several other options but these will certainly give you a good start in making selections.
Cover Crop Radishes – What they do
Cover crop radishes are “all the buzz” these days in the cover crop world. Cover crop radishes should have fairly large tubers that penetrate the soil and add many benefits. The main benefits are that they enhance percolation and aeration. Additionally they provide food for earthworms like few other cover crops. It is quite common to find 3-5 earthworms per tuber.
The question that many producers and researchers are asking is “how big” do the radishes need to be to be effective? My friend Barry Fisher, NRCS Agronomist in Indiana, leans towards several smaller tubers being better than the “State Fair” type that may be confused for a baseball bat! While the larger tubers make newspaper ads and are great for photo ops, I’m not convinced that they are necessary. On the other hand, the larger tubers do a better job of “lifting” the soil around them. It is not uncommon to find soil built up around the larger tubers at least 1/2″. (See photo)
Cover crop radishes scavenge nitrogen and other nutrients from the soil. To achieve the larger tubers it is important to have good fertility like manure or a legume planted with the radishes. If there are few nutrients to scavenge, the radishes will rarely become very large.
The main benefits of cover crop radishes
Cover crop radishes:
- scavenge nutrients from the soil (especially nitrogen).
- penetrate the soil, therefore reducing compaction.
- enhance soil percolation and aeration.
- provide an excellent environment for earthworms.
- provide deer and cattle an excellent wintertime feed.
- die in the winter (around 25-29 degrees).
Cover crop radishes may also:
- increase yields on corn by as much as 9-10 bu/acre (recorded in central Indiana).
- reduce soybean cyst nematode populations.
- improve control of winter annual weeds (this is usually the case).
When planting cover crop radishes:
- Drill 1-3# or broadcast 3-5#/acre for larger tubers.
- Drill 3-5 or broadcast 6-10#/acre for more, smaller tubers.
- Use improved selections (varieties) for more consistent results.
The main detriments of cover crops radishes
Cover crop radishes:
- stink when they deteriorate!
- may head out if you plant them too early in the summer. A late-summer planting (August-September) works best.
- need 6-10 weeks of growth for best results.
- may contain hard seed, which when sown in the late-summer, may germinate in the spring.
- may develop very deep roots in very sandy soil…which may get into field tiles…even 32″ deep tiles
Earthworms…valuable resource on farm ground
Earthworms are exceptionally valuable builders of healthy, fertile topsoil. Jill Clapperton stated that a good sign of a healthy topsoil was that a “shovel-full of soil” should have 8 earthworms in it. In my field diggings I have found anywhere from ZERO to 10 erathworms per shovel-full. I found 10 in crimson clover, 8 in annual ryegrass, 7 in my Austrian winter peas, 10 in my annual ryegrass/crimson clover mix and ZERO where I had no cover crop.
[Read more…] about Earthworms…valuable resource on farm ground
When to aerial apply cover crops into corn
A few years back many said “August 15-25” was the right date to aerial seed cover crops into corn. However, we found out very quickly that “dates” cannot be set…but timing can be. While we know that August 15-25 often can be correct, we also know that following the calendar (like in the 2009 crop) can be a mistake. So let’s set a few guidelines that should help all of us have better success when aerial applying cover crops into standing corn.
Guidelines for success when aerial applying cover crops into standing corn:
- Aerial apply cover crops when the corn plant is dried approximately to the ear.
- Aerial apply cover crops when approximately 50% of the sunlight can reach the ground between the rows. (Walk in the field a few rows to determine this).
- For success, do not fly cover crops into corn that is immature (still very green). The seeds will most likely germinate and then mold (not enough sunlight to conduct photosynthesis and too moist of conditions).
When is it too late to aerial apply cover crop seed into standing corn?
- You need 5-6 weeks of growing time for cover crops going into the winter for best winterhardiness and performance.
- Winter Cereal Rye is more “flexible” than annual ryegrass or other cover crops when it comes to the lateness of application.
- If corn will be harvested soon after an aerial application can be made, consider the cost of other types of cover crop applications (i.e. drilling the cover crop in after harvest). Utilize the lesser expensive application.
Cover Crop Seeding rates DO matter
As an agronomist I try real hard to recommend the correct seeding rates. For instance the “recommended” seeing rate on radishes has been 10-12#/acre but in reality only 3-5#/acre does a lot of good in mixes and 10-12 is WAY too thick (and expensive). Annual Ryegrass rates for cover crops is 1/2 that for forage. In fact, some producers use 12-15#/acre now and achieve very nice stands. Cutting seeding rates helps save the producer money and that is almost always a good thing, right?
However, there is another side of the coin. We do need to achieve adequate coverage to reduce erosion. Thin stands of cover crops might provide some purpose but they may also give a false sense of “security” that you’ve actually “done enough” to help. I guess the question is “what IS enough to help?” I’d suggest that 50% ground cover is not enough to give erosion control.
With the help of NRCS, past experiments in MI and OH, and other cover crop friends we determined that 35#/acre was going to be thick enough for Austrian Winter Peas and Radishes. Crimson Cover with Radishes seeded at 17-20#/acre looks just right.
So how do we know what the right seeding rate is? As I said earlier, I work with NRCS experts and do a lot of test plot work. In the fall of 2009I helped plant over 15 different cover crop test plots in OH, MI, and IN. Most of the plots are identical but in some of the plots we are experimenting on new mixes and different seeding rates. We take notice of plots that look thin and determine why. Did we get a good catch? Were the legumes inoculated so they can grow aggressively? Or, did we just plant too low of a rate?
In the plots in Southern Illinois I wrote about previously there were some plots that were quite thin. I wish I had taken photos of them. They had about 30% ground cover. The Hairy Vetch was not inoculated and it had few nodules and it was growing very slowly compared to the other inoculated legumes. I did not put those entries in the plot, but I wondered if they’d be thick enough when I saw the seeding rates they used.
It’s one thing to try to save money for the producers…and I’m all for that, IF the savings are actually savings. I guess it depends on the producers goal. Would producers plant their corn crop at 1/2 or 3/4 rate to save money?
What do you think?