Plant Cover Crops

Learning about the benefits of planting cover crops.

cover crop radishes

Cover Crop Field Day Set in Blooming Prairie, MN

PileDriver at Hagan Farms 2 33 days
This Radish was planted in late July 2013 and after 33 days has tremendous growth. This mix included oats and crimson clover and radishes.

Cover Crops will be the main topic of discussion on September 4, 2013 at a cover crop field day and meeting in Blooming Prairie, MN. I have the privilege of speaking at this event as we look at cover crops on prevented plant acres.  We will also look at what cover crops work best in the upper Midwest.  We will be on Brad Hagan’s family farm and possibly look at Dale Ramsey’s farm too.  Please note that we will be looking in root pits (where the action really is)!

I received this note from Legacy Seeds representative Andrew Heath about the field day/meeting:

“We  plan on structuring the event much like an open house with designated times where you will be able to address the crowd. We will start the event at 10 am and have you speak from 11 to 11:45 and again at 1 to 1:45. There will also be transportation to the cover crop plot and some of the field that you, TJ, Brad and I visited earlier with root pits dug. This will happen from 12 to 1 and 2 to 3.”

I have seen the plots and have added photos here on this post to entice you to come if you are in the region.

As a side note, Hagan farms will be no-tilling corn into these fields in 2014.  We’ll follow-up on these fields next spring and see how these fields compare to others that did not have a cover on them.

This prevent plant field had plenty of nitrogen from manure to capture. Hagan farms used a hybrid brassica and spring barley to secure the nitrogen and Berseem clover to produce more N and provide better soil health.
This prevent plant field had plenty of nitrogen from manure to capture. Hagan farms used a hybrid brassica and spring barley to secure the nitrogen and Berseem clover to produce more N and provide better soil health.

Cover Crops and Prevented Planting Guidelines

There are thousands upon Thousands of acres - mainly in the upper Midwest not planted in early June 2013.
There are thousands upon thousands of acres – mainly in the upper Midwest still not planted in early June 2013.

Over the past few weeks I have heard from countless farmers in Wisconsin, Minnesota, Illinois, Missouri, Michigan, and Iowa that are considering taking prevented planting on all or parts of their farms. Growers Edge just published an excellent piece Prevented Planting Guidelines. 

Also see my articles on Prevented Planting Row Crop Acres – Which Cover Crops Can Help? and Summer Annual Grasses for Cover Crops for Prevented Planting Acres that may also be helpful.

Be Aware of Dormant Seed in Cover Crops

As Oregon and other west coast farmers try to keep up with the demand of getting seed back to the Midwest from their newly harvested crops, we are beginning to see some potential issues with just-harvested seed.

In the past, supply was usually greater than demand at harvest time. However, seed companies and farmers now have been clamoring for the seed…it seems from right out of the combine in Oregon!  In some ways this is very exciting, but in other ways it’s challenging.

One of the the bigger challenges outside of logistics is seed dormancy.  In the following few paragraphs we will look at two species that seem to have risen to the top of the heap when looking at seed dormancy issues.

Seed Dormancy Issues

Radishes

Here are just the few events I’ve personally witnessed with radishes:

  • In the fall of 2010 I saw pictures of big radishes in dry beans in the thumb of Michigan.
  • In May of 2011 I saw pictures of radishes 15″ tall (as tall as the corn).
  • In the spring of 2012 I saw radishes coming in the corn at our family farm.
  • In the fall of 2012 I saw radishes and annual ryegrass coming up from seed that was planted in September 2011.

How do these events happen?  I know that for sure the weed control on our home farm was “excellent” all season long and that there was a “follow-up” herbicide application to make sure that there was outstanding weed control.  However, there they were!  We had BIG radishes in the soybeans at harvest time.

Beans are ready for harvest but radishes can create a headache if not controlled with season long scouting.
Beans are ready for harvest but radishes can create a headache if not controlled with season long scouting.
How would you like these running through your bean head? Me neither. Thankfully they did not cause any issues but we need to be watchful and use full season herbicides if we don’t want to ever see this.

How could these radishes be in the soybeans?

Radishes have a small percentage of “hard” or “dormant” seed.  Usually 4-5% of what is sown will not germinate right away, but will instead come up at a later time, from 1 season to 50 seasons later.  While this will rarely ever cause problems, we need to be aware of it.  The 2012 drought, combined with the heat and later rains, proved to be a great environment for radishes to start growing in August.  By harvest time in October we had very big radishes.

Be sure to talk to your seed supplier about when your radish seed was harvested. You will possibly have less issues with radishes that were harvested the previous summer instead of the previous few weeks.

These radishes were easily killed with the second spray of the season. However, I wish that the initial residual herbicides had controlled them as we anticipated they would have.
These radishes were easily killed with the second spray of the season. However, I wish that the initial residual herbicides had controlled them as we anticipated they would have.

Annual Ryegrass

Annual ryegrass gets a lot of hype and also a lot of guff.  I’m not sure which one bothers me the most.

Annual ryegrass has many outstanding qualities as well as some challenges.  Dormant seed is one of those challenges.  Annual ryegrass needs to “cure” for a time – or to dry fairly thoroughly for its germination to be consistent – the 90-95% that we expect and appreciate.

However, when we go from “combine to airplane or drill” in a very quick time period we are “rushing” the seed so fast that some of it lays dormant for a time.  How long?  Maybe a few months or maybe a year.  On our home farm we had an outstanding kill on our annual ryegrass (and everything else).  Yes, it took two applications to accomplish that but we were very well pleased with the kill on our cover crops.  And we were thrilled with the results!

However, when we were looking at our corn plots in August I gave the “uh-oh” to Hans Kok, Dan Towery, and my brother Don Robison.  As in “uh-oh, we have annual ryegrass coming up.”  In this case it was not a big deal because it didn’t bother the corn harvest and we’re planting soybeans in the spring.  But, what if we were going to wheat?  We would have sprayed and killed the young seedlings if we noticed them becoming a problem.

In the middle of August we were seeing annual ryegrass and radishes coming up that had been SOWN THE PREVIOUS SEPTEMBER!
By November we had vigorous growth and a thicker stand than we had the year that the cover crops were actually sown.

There is no doubt that cover crops are a valuable tool.  But with the demand for cover crop seed, I think we will have issues that some of us never dreamed of –  in addition to the benefits that are beyond our imagination.

To achieve the best possible benefit and profitability we need to manage well.  The cover crops that came back into our corn should be of great benefit to next year’s soybean crop – even though we didn’t plant them in the fall of 2012, but rather in the fall of 2011, a year earlier!

So should we NOT use annual ryegrass or radishes?

Of course we should use them. They are outstanding species for cover cropping.

Should we buy seed a year in advance?

That is probably not feasible for most farmers and you surely need a rodent proof storage area!  And good luck finding enough “extra” seed.

Manage Well

Since we’re learning that cover crops increase profitability on the farm, our focus needs to be on proper management. Very simply, use a long-lasting residual herbicide, scout and spray as needed, and be aware that some cover crops species have dormancy issues.  If you are going to follow with wheat, be sure to apply herbicides that kill annual ryegrass in the fall so the annual ryegrass  does not live and cause issues in the wheat the following summer.

It all comes down to managing your cover crop well.  Most farmers have few if any problems, but stay alert. You must be on guard to achieve the greatest benefit from your cover crops.

Is it Ever Too Early to Plant Cover Crops?

Is it ever too early plant cover crops?  YES.

As many of you have figured out, I sell seed for a living.  I also have been a farmer or involved on the farm since I was a little boy.

But first and foremost I am an agronomist.

The temptation of a seed salesman is to recommend planting a cover crop either too early or too late – and then somehow justify it. However, as an agronomist and a former farmer, I simply cannot do that. I also want to be able to look at myself in the mirror without guilt.

Cover crops have to work for the farmer, not the seed salesman.  There are several fantastic seedsmen out there and I do not want to disparage that fine profession.  I feed my family by being a seedsman and marketing seed. Most seedsmen are a trusted source of information and quality seed.

Questions I Get A Lot

The planting date question comes up a lot. For example:

  • How soon can a farmer plant cover crops after wheat has been harvested?
  • Can a farmer plant clovers into corn at “the last cultivation?” (even though only a few farmers still cultivate).
  • When is it too early to plant radishes?
  • When is it too late to plant radishes?

Money has not always been good in agriculture and I doubt that this current boom will last forever (it never did before).  So I want to give answers based on sound agronomic practices that will work 90% of the time.

Question: Can you plant crimson clover at “lay-by”?

Yes you can.  My granddad did that practice back in the 1950’s.  Of course he planted in 38″ rows with 16-18,000 plants per acre.  He did not use herbicides but he did cultivate.

However, how many of us farm like my granddad did?  A few of you might –  with good reason to do so (specialty corn or organic production).  But, can it work with modern herbicides and plant populations pushing 35,000 plants per acre?  Maybe, but not consistently – and probably not.

I think I tried to say “no” but I’m aware that some farmers have done it.  But, can we do a practice if it is not going to work 90+% of the time?  Not on a large scale.  Can we afford to try it on a few acres?  Maybe.

Here is a northeast Indiana farmer’s testimony of his success spreading crimson clover into his growing corn at sidedress time.  I am sharing this exactly as it was sent to me – trusting that it is accurate. I do not know the farmer who submitted the testimony.

I broadcast 10 lbs/acre of crimson clover at sidedress time this year. I seeded it on 6/6. We got essentially no rain from the first week of May until the last week of July. I figured the clover wouldn’t grow, but it laid there until we got rain and by harvest we had a nice stand. I’m not sure how this would work in a ‘normal’ year, but it sure worked good this year. I left some check strips and the clover didn’t affect the yield.   The seeder was just an old 12V spinner seeder I clamped onto our N toolbar. I’m attaching pictures of it and the clover stand. 

Photos provided are below.

My Observations

My guess is that this farmer used only glyphosate and no residual herbicide.  It was also terribly dry this summer and this seeding would have been more like a “dormant seeding”.

This was not at all typical for an Indiana summer. It was the driest July on record and June and August were also very dry.  Note how short the corn is in the photo with the corn head.  There was a lot of corn 3-5′ tall this year in Indiana.  I’d guess that a 5 foot height would cover the corn height in this field.  If the crimson would have been planted in a “normal” year I would be surprised if he would have had success like this.  But, boy, it sure is a beautiful stand in these photos!

If you try this practice, just experiment with a few acres to see what works on your farm.

Seeding Crimson Clover at “lay-by” in June in NW Indiana.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Note how short the corn is in the photo. Contrary to the belief of Illinois and Iowa farmers, this is not typical for NW Indiana corn! Most likely the rains that came in August were adequate to germinate the clover and there was plenty of sunlight getting to the ground so the seedlings had heat, moisture, and sunlight. What a beautiful cover crop!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Here is a beautiful stand of crimson clover between rows of harvested corn! Unfortunately the lack of corn fodder shows that the corn was under severe stress in 2012. While achieving a nice cover crop is important, I would prefer 200+ bushels/acre corn and a less advanced stand of clover at harvest time.

Question: Can you plant radishes right after wheat harvest?

No.

Even if you use an excellent radish,  it will bolt.  I don’t care which radish you use – it WILL BOLT if you plant it too early in the summer.

Bolting means that it will try to produce seed.  Generally a radish that bolts has a smaller and shorter tuber and most of the plant energy goes to seed production instead of root tuber production. If you wait until early August and use the proper radish you will see very little if any bolting.

I have been in several fields this fall that had no plants bolted.  I have also seen many fields that had a high percentage of plants that bolted.  Some claim that the exceptionally high soil temperatures in the summer of 2012 caused the August planted radishes to bolt.  That may be the case.  One thing I know for certain, if a radish is planted in July, it almost always bolts and can produce viable seed in the fall – and that could create potential problem for years to come.

Dave’s Best Advice

Wait until August to plant your cover crop radishes.  Use the few weeks between wheat harvest and planting cover crops to clean up weeds that were in the wheat field and also control volunteer wheat.  Patience is a great virtue.  It is important that you see an excellent return on your investments that we make in cover crop seed and seeding cost.  Our goal should not be “to be done first” but rather to have the best cover crop and healthiest soil.

I hate seeing fields like this as I know there was potential for seed to be produced and dropped to the soil possibly creating some issues in future years. Was this field planted too early or was the wrong radish planted? I do not know but I do know that farmers should chose wisely on planting time and what radish to plant.  Thankfully not every plant bolted so there are still plenty of plants “doing the radish thing” in the soil very well.

Cover Crops Provide Improved Corn Yields in On-Farm Trial

All of what is reported below was accomplished after only one year of cover crops.  This work was inspired by a conversation Don and I had last winter with Dr. Eileen Kladivko from Purdue University.  As I say in cover crop meetings,

Don’t expect a miracle the first year – but look for one.

Over the exceptionally dry and super hot late-spring/summer months of 2012 my brother Don Robison collected “plant-health” related data on our corn field at Robison Farms near Greenwood, IN.  Don took data on the corn  from each area of the cover crop plot we planted last fall over the top of a soybean field as well in the “check area” (no cover crop area).

The data he took throughout the summer included plant chlorophyll readings, plant height, and compaction readings.  I presented some of the chlorophyll data on the CropLife Webinar and at several cover crop meetings this summer (and more is posted below).

On August 15th Don and I took hand harvested yield checks from each area and from the check area.   The data on the corn yield was almost identical to what we found with the chlorophyll data and compaction data. Where we had the healthier plants all season long (more “green-ness” and deeper roots) we had higher yields.

To figure yield we utilized this formula we found at a Purdue University agronomy website.

Each cover crop treatment out yielded the “no cover crop check”. The top three yielding plots also had the least compaction and highest chlorophyll readings through out the drought stricken summer.  The check plot yield was 105.24 bushels per acre.  The top yield estimate was 164.82 bushels per acre.

 

The area where the plot was had a 24″ water line was installed by the county in 2009; so it was intended to be a “rescue disturbed soil trial”.  The corn was not harvested directly over the water line but it was where the soil from the water line was mixed in with the top soil.  In 2011 the field was in Soybeans and yielded 48 bushels/acre.  In 2010 the field was corn and yielded 198 bushels/acre.  The whole field has been no-tilled for most of the past 20 years (there were some years with conventional tillage done – mainly in the early 90’s).  175 Units of N were applied (100 units (28%) with the chemical burn down application early season and 75 units side dressed (28%) in early May).

Rainfall from May 1 to July 31 was 2.24″ (with only 0.75 from May 1 to July 19).  There were 42 days over 90 degrees and 8 days over 100 degrees during that time.  All time record dry and heat was recorded in July, 2012 in the area.

Don took chlorophyll readings weekly (one week missed in July due to a family vacation).  He took 30 chlorophyll readings per plot per sampling date.  He also took multiple plant height readings each time as well.  He followed the manufacturers instructions on the chlorophyll readings and penetrometer tests.  Don spent a lot of time in this field so we could all have this data!  Thanks to The CISCO Companies for providing the seed, equipment, and Don’s labor to collect this data.

 

This chart shows the percentage above the no cover crop area (the “check”) compared to the different cover crop mixes. The two comparisons on the far right are from a soybean study we ran where we had cover crops two consecutive years compared to one year (more data and a post coming soon on this study).

Observations:

  • The plot areas that rated healthier (more green-ness and taller) yielded the best.
  • The plots areas where there was less compaction yielded the best
  • The plots with annual ryegrass did not fare as well as some others in this drought year – yet was still considerably above the check.
  • Not all plots with radish were “top” yielding – however two of the top three yielding plots had legumes plus radish.
  • Plots with legumes were generally healthier all season long and their yield reflected that.
  • I doubt that the whole field will average over 100 bushels/acre.  As with all hand yield tests they are estimates but I believe that the comparison is very accurate.
  • The Austrian Winter Peas, Crimson Clover, and Appin Turnips overwintered “beautifully” and were growing aggressively when sprayed at burndown.
  • There was a considerable amount of earthworm activity in the cover crop area but only a few earthworms were found in the “check” area. That is unfortunate because 2 acres were covered and 48 acres were not!
  • There were more corn roots in the plot areas we dug vs. the check area (watch for a new post coming on this soon).
  • There was more moisture in the soil where the cover crop plots were compared to the check area.
  • The soil structure was considerably better in each cover crop plot vs. the check area.
Don recorded over 180 chlorophyll readings in each cover crop plot and check plot over the summer.

 

The check plot had 175 units of nitrogen plus the whole field had been soybeans the previous year. While the annual ryegrass blend plot was above the check all season long it was not up to the desired level until after the July 19 rain event.

 

The plot with the Oats and Rye and Appin Turnips was impressive most of the spring and summer. It was at or above the desired rating until August. It was very impressive right after the July rain event and that is possibly why it had the second highest estimated yield. By the way, the turnips did live through the winter.
All season long I was convinced that the plot where the Austrian Winter Peas and Radish were was going to have the highest yield based on the data shown above (and plant height readings). It beat the second place entry by less than 1/2 bushel in the yield estimate.