Plant Cover Crops

Learning about the benefits of planting cover crops.

Radishes

Cover Crop Turnips – A Good Choice Over Radishes?

Cover Crop Radishes or Turnips as a Cover Crop – or Both?

Cover crop radishes certainly receive a lot of press. I have researched them quite a bit over the past four years. On this blog alone I have over 20 posts about radishes. They are fun to take photos of, dig around in, research, and even play baseball with.

It is hard to pick up a publication that mentions cover crops and not read about radishes and their benefits.  Some industry and university cover crop research leaders like Steve Groff and Dr. Ray Wiel (University of Maryland) have researched radishes for over 10 years.You might say that cover crop radishes are the “Rock Star” of cover crop species these days.

What About Turnips?

The Oats are nearly 30" tall and the turnips are around 18" in this Oactober photo. The Cereal Rye was about 6" tall at this time. This mixture was planted in late August and the photo was taken Oct 22 - approximately 8 weeks after planting. My daughter Grace was the model..
The Oats are nearly 30″ tall and the turnips are around 18″ in this Oactober photo. The Cereal Rye was about 6″ tall at this time. This mixture was planted in late August and the photo was taken Oct 22 – approximately 8 weeks after planting. My daughter Grace was the model..

Why are turnips used as a cover crop so little compared to radishes? Are they the “ugly step-sister” of the Brassica family?

Let’s look at some of the benefits of turnips. Some newer varieties (Appin in particular) provide a bulb that is almost entirely in the soil and a deep root system (though a smaller bulb/tuber than the radish).

Benefits of Turnips

  • Turnips are very palatable for grazing cattle and sheep.
  • Most turnips survive the winter and hold onto nutrients into the spring (longer than radishes).
  • Turnips sequester nutrients in a similar fashion and amount as radishes (see data below).
  • Turnips are easy to kill in the spring.
  • Turnips do not have the odor problems that radishes have (therefore they can be planted more “safely” in areas closer to towns or neighbors).

“Problems” with Turnips

  • Not all turnips are created equal. The old purple top (or that type) turnip and even the tankard type turnips have very little of the bulb in the soil – thus less soil activity.
  • Most turnips survive the winter and then need to be killed in the spring. Yes this can also be a benefit.
  • The turnips “bolt” in the spring and want to produce seed. Kill them as early as possible.

    Turnips will overwinter in the spring. The turnips above flowered out in March 2012 in central Indiana. This is nearly 5 weeks before “normal”

Frequently Asked Questions

  1. If we mix turnips and radishes together, is that okay?  YES – for grazing or for just using as a cover crop.
  2. If we plant turnips instead of radishes is that okay?  Yes – just be aware of the differences and that the turnips will most likely survive the winter.
  3. What if we are just looking to graze and only care some about the cover crop?  Choose turnips.
These three brassica types were collected from a Loundonville, OH farm in the fall. Pasja Hybrid Brassica (L); GroundHog Cover Crop Radish (C); and Appin Turnip (R). Note the difference in tops versus tubers.

 

Nitrogen tested in Radishes/acre from Loudonville, OH dairy farm  averages 200 units of N (data collected November 2010)

Nitrogen tested in Appin Turnip/acre from Loudonville, OH dairy farm showed nearly 300 units of N (data collected November 2010)

The turnip tops had nearly 200 units of N/acre.  This was NOT scientific but it is instructive that turnips are an excellent scavenger of N.

Planting cover crop radishes with wheat? How do you plant them?

Planting Cover Crop Radishes with Wheat – A Growing Practice

Cover crop radishes planted with wheat at seeding time?

Last year I posted about how farmers in NW Ohio are seeing increases in wheat yields by 4-7  bu/acre by planting 2-4# of cover crop radishes in with their wheat seed. In the fall of 2010 there were more acres of wheat planted in Indiana, Ohio and lower Michigan than in many years before, and several of those acres had radishes planted with them with the hope of increasing yields.

Several test plots were planted as well. Unfortunately, the seed was planted into very dry soil and it did not rain until late October or early November so the radishes grew very little (if at all).  So the grand “radish seed planted in with the wheat seed” experiment was pretty much a flop in 2010 in the eastern Corn Belt.  However, I heard reports from Oklahoma and New York that claimed to see value in this practice.  By the way, 2# per acre is plenty.  4#/acre is too much seed.

How to Mix Cover Crop Radish Seed with Wheat Seed

As I have shared about this potential practice around the Midwest I often-times get the question, “How do I mix the radish seed with the wheat seed?”

Option 1

I first mention the “coffee can and paddle” approach of adding the seed.  As you fill the drill add some radishes and use a paddle (or even a tree limb) to stir it in.  With that approach I usually get a confused and almost angry look from producers that think I am mocking them (Seriously, I am not!).

Option 2

Since most farmers are more sophisticated than that I recommend adding the radish seed to the wheat seed at the seed house.  Then I get angry calls from the wheat seed suppliers about adding a “weed seed” into their bagging system!

Option 3

So I have concluded that the easiest way (and the way to recommend that will not get me in hot water) is to add the radish seed with the fertilizer that will be applied just before or after the wheat is planted.

Option 4

I’m open to suggestions.  If any of you do this differently will you please help out our fellow wheat producers?  Thanks!

These radishes are about the size we should expect to see when the season ends if planted with wheat. These radishes show the potential growth in just over 6 weeks since planting..

 

 

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

Cover Crop Radishes…be a good neighbor!

As I look at the forecast for Valentines week I see mid-4o’s on the way!  Hallelujah! With many areas from Colorado to Virginia under ice or snow this will be a very welcomed relief.  But with warmer temperatures on the way I think it’s important to “be a good neighbor”.  We want our neighbors to be excited about us using cover crops, right?  Well, when the radishes “start to a smellin'” we should make sure that the neighbors know what is going on.  Also, let the local gas company, local fire department, local farm store, local grocer, local postal worker, etc…know that the smell that is emitting around your fields of radish is the smell of good stewardship!  Click here to see that Radishes have many benefits!

Radishes have great benefits and grow well with minimal water (as seen on Mike Werling's farm in 2010). However, when they start smelling bad, let the neighbors know what is going on...so they will "enjoy" the fact that you are doing great things for the soil and groundwater.

The main challenge with Radishes is the odor they emit as freezing and thawing occurs.  As good stewards we should consider using them…and being forthright with our neighbors.