Plant Cover Crops

Learning about the benefits of planting cover crops.

Improved Varieties

Cover Crop Radish Research reveals interesting data and information

In the summer of 2010 I entered a number of “cover crop” radishes into research plots in Michigan and Minnesota.  Some of the products I entered were given to me from a supplier in Oregon. They had collected seed samples from Europe that had been touted as cover crop worthy.  They weren’t. Fortunately those varieties never hit the US market – that I am aware of.

I also entered two other radishes that actually performed very well.  What we found is that not all cover crop radishes are created equal.  While many of the top selling radishes grew the way you would hope, there were some that did not perform well at all.

Here’s what I mean: The “lesser performers” either bolted and went to seed production early, or they had very small tubers, or both.

Now in the summer of 2011 we have planted new plots in MI and MN along with some plots in my garden “agronomy plot” in Winona Lake, IN (NE IN).  I planted my plots WAY too thick as it was very dry and I was hoping to get emergence.  I watered two times after planting the plot and that helped quite a bit.  Over the last week we received nearly 5 inches of rain, so I have a very thick, robust radish stand.

What I am seeing after 6+ weeks of growth is interesting.  I purposely planted the “wild looking radish” (“VNS Daikon Radish” on the tag) that was sold out of North Dakota in the summer of 2010 so I could compare it to Oregon grown VNS Radish.  I included two named products, GroundHog and SoilBuster (a mixture of two varieties) in the plot as well.  On the GroundHog I entered seed from two different years 2009 and 2010 to check for consistency (GroundHog is actually a true single variety of radish).

VNS stand for "Variety Not Stated" and in some cases "Buyer Beware." The Oregon grown VNS Daikon Radish is a far superior radish for cover crops than the VNS Daikon Radish from North Dakota.

I have a few early observations on these 6+ week old radishes (planted August 19, photos taken Oct 6):

  • The GroundHog from both seed crop years look the same (green top on tuber, similar tuber type and size).
  • The Oregon grown “VNS Daikon Radish” is far better than the North Dakota grown “VNS Daikon Radish” (seed purchased from the Pulse Group).
  • The North Dakota grown “VNS Daikon Radish” looks like it did in 2010 – already bolting (it started bolting at 4 weeks) and very little root.
  • The Oregon Grown “VNS Daikon Radish”  has shorter top growth than both GroundHog and SoilBuster.
  • The Oregon Grown “VNS Daikon Radish”  has smaller tubers than both GroundHog and SoilBuster.
  • GroundHog had more top growth than SoilBuster.

My conclusion so far:

The two named radishes (that are actually varieties) seem to actually show more “value” (more top growth and larger tubers) than either of the VNS products.  What does that mean to producers?  That maybe the few extra dollars you pay per acre is actually money well spent.

Both named products showed larger tubers and more top growth than the Oregon Grown VNS Daikon Radishes.

 

 

 

 

 

 

 

 

 

 

The tag from the North Dakota VNS Radish. Notice the "ND" under origin in the upper right. Click on the image to make it larger.

 

Photo diary- Corn after a cover crop (after corn)

“Planting this corn field was like planting into a garden” said my friend Dave.   He has been a ‘cover cropper” for six years now.  This year Dave no-tilled approximately 50% of his acres.  Dave is one of the most innovative guys I know…but he’s also “cautious”; he does not want to lose money!  That’s why Dave loves cover crops…using cover crops he has improved his profitability.  In this photo diary we will look at photos from April, May and June where Dave had a cover crop consisting of Oats/GroundHog Cover Crop Radish/AU Robin Crimson Clover.  The previous crop was corn.

An April view of the field with the AU Robin Crimson clover that over wintered. The oats and GroundHog Radishes had died out over the winter as expected.

 

A May photo of Crimson Clover that could not be killed yet because the field (and all other fields in the area) was too wet to spray. Normally by the date the photo was taken the Crimson Clover would have been dead and the corn would have been planted.

 

No-Till Corn on Corn planted into Oats and AU Robin Crimmson Clover

What if a cover crop dies over the winter…was it still valuable?

As I take phone calls and conduct meetings I ask producers if they want to have the cover crop they are choosing to overwinter or die during the winter.  I’d guess that the answer as split 50/50. The biggest reason for wanting the cover crop to die is that producers don’t want to have “to mess” with killing a crop in the spring of the year.  Other advantages that folks mention is that they believe that the soil will be warmer if there is not a living cover in the field.

This mixture was planted on time but had very little moisture in the fall of 2010. All things considered it is a beautiful stand. However, the crimson clover is so short that I hope that it overwinters so the producer can get "maximum" nitrogen benefit for the 2011 corn crop.
On November 17, 2010 we found annual ryegrass roots 40" deep after just 10 weeks of growth. We want this field to overwinter...but we already have accomplished nutrient management goals by holding nutrients from the manure applications. If the field overwinters I believe we may find roots 70" deep when we dig in April 2011.

Advantages of having a “short-term summer/fall cover crop” is that you should still control the majority of the winter annual weeds, many legumes will still produce a good amount of nitrogen before winter (Austrian Winter Peas, Cowpeas, Crimson Clover, Berseem Clover, Field Peas, etc…).  Radishes and turnips will do their nutrient scavenging and plow pan cracking work before the killing freeze too. Even annual ryegrass might have produced a pretty good root system before it goes winter dormant (or dies) depending on the seeding date/fall growth. (See  details of what we found in an annual ryegrass field in the fall of 2010.)

So what would be the advantage of a winterhardy cover crop?  Improved spring erosion control, more living roots in the soil for a longer time period, more spring-time earthworm activity, more nitrogen produced (from legumes) and over a longer time period, minimal soil temperature change (versus a dead cover crop or no cover), a longer grazing time period, to name a few.

Disadvantages of the crop overwintering would include the risk of a very wet spring causing trouble getting the crop killed, possibly cooler spring soil temperatures, and possibly some reasons that don’t come to mind.

If using a legume like clover it seems to be advantageous to have it overwinter, however Berseem clover possibly produces the most N of any legume…and it is sure to winterkill in Midwestern winters.  And I like Berseem clover when it fits the producers situation.

So, does it matter if the cover crop survives the winter…even if it dies when you expected it to survive?  My answer is that there are still benefits on most cover crops IF they were productive in the fall/winter.  If you have a late planted cover crop that has minimal growth in the fall and then it dies…you possibly “wasted” money.  Do your best to plant cover crops in a timely fashion.  Give them the best opportunity to do their best!

You don’t always get what you want…but often get what you pay for!

This photo is from the Thumb of Michigan where we had great success with the Radishes (these were GroundHog Radishes). The seeding rate was 10#/ac and planted w/o a companion crop.

Over the past number of weeks I’ve noticed quite a difference in radishes growing in farmers fields.  Some are outstanding and consistent; deep and fairly large tubers (tuber girth seems to be related to fertility and age of stand).  In the thumb of Michigan I saw over 300 acres of fields planted at 10#/acre that were just what the farmer wanted.  We found tubers 8-12” deep and we could not really find the real bottom of the roots as we broke them off in the soil.

These VNS Radishes from North Dakota are fully headed out and now a weed for producers. Unfortunately, no one in the Midwest knew there would be a problem...but boy there sure was.

While some varieties have good tubers in other instances I have found real problems.  In a field in NE Indiana a SWCD director brought some radishes from a farmer’s field that did not look good.  The farmers planted around 100 acres of a VNS radish from North Dakota (labeled as “Daikon”) and he was not happy.  I don’t blame him…look at the photo below.

What makes this story even more interesting is that the VNS radish (VNS = Variety Not Stated) from North Dakota cost the farmer 30-40 cents less per pound than the GroundHog.  Unfortunately, he’s unhappy because his radishes are not performing.  I’ll say it again…”VNS could equal Very Nasty Seed”.  The farmer saved $3-4/acre and is frustrated.  Two things…and this is for dealers and producers…#1 –Choose to buy from a trustworthy source #2) IF there is a big price savings…beware there is a reason for that spread!  Saving 15-20% on seed is HUGE!  If there is that much saving ask questions and get good answers!

Big Differences in Cover Crop Radishes

This tuber of GroundHog Radish was fairly typical where there was good fertility. This came from a very sandy soil near Melvin, MI. The farmer is very pleased with the results on his 300 acres of radishes.

There are big differences in cover crop radishes.  Some are outstanding and consistent; deep and fairly large tubers (tuber girth seems to be related to fertility and age of stand).  In the thumb of Michigan I saw over 300 acres of fields planted at 10#/acre that were just what the farmer wanted.  We found most of the tubers 8-12” deep and we could not really find the real bottom of the roots as we broke them off in the soil.

These GroundHog Radishes were all within 30” of each other on a blow sand hill. While not all are big, they are all holding nutrients.
 

While some varieties have good tubers, in other instances I have found real problems.  In a field in NE Indiana a SWCD director brought some radishes from a farmer’s field that were verysmall.  The farmer planted around 100 acres of a VNS radish and he was not happy.  I don’t blame him…look at the photo below.

The three radishes to the left are VNS and the radish to the right is the GroundHog variety. The VNS had been in the soil for 3-4 more weeks than the GroundHog radish.

What makes this story even more interesting is that the VNS radish (VNS = Variety Not Stated) cost the farmer 30-40 cents less per pound than the improved variety.  Unfortunately, he’s unhappy because his radishes are not performing.   The farmer saved $3-4/acre and is frustrated.  Two things…and this is for dealers and producers…#1 –Choose to buy from a trustworthy source #2) IF there is a big price savings…beware there is a reason for that spread!  Saving 15-20% on seed is HUGE!  If there is that much saving ask questions and get good answers!

Crimson Clover; a jewel among the cover crop legumes

bee on crimson clover
Crimson clover is a top nitrogen producer and beautiful as well.

Crimson clover is a real jewel among the cover crop species.  Crimson clover is an excellent producer of nitrogen and there are some newer varieties on the market that are very winterhardy even into Michigan.  Dr. Eileen Kladivko measured how much nitrogen was produced by crimson clover in a test plot in western Indiana.  What she found was quite amazing!  After around 90 days the crimson clover had produced over 140# of nitrogen per acre!  Now, this was a limited test of one plot but the best of the other plots came in at just over 50# N produced.  That is a significant amount of nitrogen.

Crimson clover mixes very well with annual ryegrass (to help the ryegrass be healthier and growing better when there is no manure applied).  It also mixes well with cover crop radishes and or turnips.  Crimson clover is generally considered more shade tolerant so it works well aerial applied into standing corn.

Crimson clover MUST be inoculated for best success.

I have listed some advantages and disadvantages below:

Advantages of Crimson Clover:

  • There are some excellent new varieties on the market that are more winterhardy.
  • There are earlier maturing varieties that mature early enough to make more N in the spring before killing.
  • At around 90 days after wheat it can produce upwards towards 140 units of nitrogen.
  • Earthworms love the environment around the roots of crimson clover…it’s creates “earthworm heaven!”
  • It is easy to kill in the spring.

Disadvantages of Crimson Clover:

  • VNS and MOST older varieties will probably not survive the winter in the Midwest.
  • It has some hard seed so you may see some coming up some months after planting.
  • If it is a very late wet spring there is a slight chance the clover will re-seed itself.

Crimson in ARg
Crimson clover mixed with annual ryegrass is a great cover crop combination.
Crimsom roots
Properly inoculated crimson clover produces large and multiple nodules. Note the root hairs as well.