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.
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?