Plant Cover Crops

Learning about the benefits of planting cover crops.

Education

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!

May planted Radish Plot final results 8/4/2010

GroundHog Radish consistently had the larger and deeper tuber of all varieties tested. This photo is from the ~5#.acre seeding rate plot.
This photo shows the GroundHog Radishes dug from the ~12-15#/acre rate plot. Note how much smaller the tubers are than the 5#/acre rate.

It’s been 10 1/2 weeks since I planted my Radish test plot in my garden.  I have recorded photos and reports in previous posts and now this is the “FINAL JUDGMENT” of the different varieties that were included this spring.  I’ll report mainly via photos and captions.  Just a reminder, about 5 weeks ago I thinned out plots of each variety so I’d reflect 2 different seeding rates; ~5#/acre, and ~12-15#/acre.  The goal was to see if seeding rates matter and also if we can use fewer radishes and still accomplish great results.

I’ll be planting another radish plot in a week or so to see how a mid-summer planting plots might differ.  I’ll also add some of the other popular varieties/brands and two more experimental varieties folks are sending for us to test.

This variety had the single largest radish...but only the one radish was of any size. This was from the ~5#/acre plot.
This is from the ~12-15#/acre plot area. One of the radishes was of good size but the others were quite small when compared to GroundHog.
I don't know how to say I'm disappointed in a variety...but this one sure surprised me. At first I called it "stubby". Later I found it "intriguing" because it had such a long skinny tap root. Now I call it "disappointing". I was anticipating lots of long skinny roots 15" deep or so...and all I got was what you see above. This is from the ~5#/acre rate plot.
You can see big differences in these two varieties both shown at the ~5#/acre rate.
This variety was one that I pegged early as one I thought would be the "best" radish. Needless to say, I was wrong. This is from the ~5#/acre plot.
Columbia from the ~12-15#/acre plot.

Cover Crop Radish – Rate Per Acre

Radish plot 7-10 028
Two different cover crop radish varieties both had larger tubers in the area where I thinned the plants to 4" apart (shown).

In my cover crop radish plot I have thinned some rows to 4″ between plants and in two rows I have left them thick (I figure I’m at the 12-15#/acre range). After 6 weeks there are some pretty telling signs that 12-15#/acre is too thick and possibly a waste of money.  Most of the varieties that have been thinned to 4″ have larger tubers than in the thicker plots.  That is not always the case, but I think it’s safe to say that the heavier planted radishes do not have the larger of the tubers.

Radish plot 7-10 011
Cover crop radish tubers planted at the 12-15#/acre rate after 6 weeks.
Radish plot 7-10 013
Here is the same variety at 6 weeks when thinned to the approximately 5#/acre rate.

Cover Crop Radish Plot from July 10, 2010

Radish plot 7-10 022
Groundhog cover crop radish was consistently the largest tuber in the plot
Radish plot 7-10 013
This variety is one I called "Stubby" 2 weeks ago...I'm not sure what to call it now! Maybe "the most interesting radish in the world..."

My cover crop radish plot was planted on May 29, 2010 and now 6 weeks later we can see some characteristics even different from 2 weeks ago. 

A variety that was 8-9″ deep 2 weeks ago still appears to have that same depth. 

Another that I called “Stubby” is now looking quite interesting! 

Yet another variety, Groundhog, is showing the best depth and girth so far…at least the biggest girth at 8-9″ deep. 

One variety has a very long tap root but very little girth at all…in fact it looks like a small turnip with a 15″ tap root! I’ll leave the plot in for another few weeks but then rip it out and plant some late squash for the family.

Winter Cereal Rye

One of the most popular cover crops is winter cereal rye.   It is a very versatile cover crop that has few disadvantages.  While it does not have the deep, nor fibrous root system that annual ryegrass has, it reportedly has had 45″ deep roots found in north-central Indiana in May.  Winter cereal rye can be planted later in the fall than other cover crops and still have an excellent stand the next spring.


Advantages of Winter Cereal Rye:

  • Excellent winterhardiness
  • Very good for erosion control
  • Good root depth
  • Can be planted later than other cover crops
  • Makes very good haylage
  • Early maturing so following crop can be planted earlier
  • Assists in weed control for subsequent crop
  • Good scavenger of nutrients
  • Very good for aerial application
  • Very good for winter and spring grazing
  • Makes very good “green manure” if plowed in
  • Mixes well with oats and turnips

Disadvantages of Winter Cereal Rye:

  • Potential for alleopathy issues with following crop (not likely)
  • Not the top choice for erosion control or rooting depth
  • Spring growth can “get out of control” if not killed early
  • Not much fall growth for forage
  • Not the top choice for forage quality

To view a video on Cereal Rye and Radishes watch below!

Grazing Cover Crops in the Winter

Over the past 9 years I have worked with Ed Ballard from the University of Illinois on grazing cattle over the winter.

During the first 4-5 years I was much more concerned about the “above ground” aspect of the cover crop and weight gain by the animals.

However, these past 4-5 years have shown me the dual benefit of this amazing plan.  The mix I use is 1-1/2 to 2 bushel per acre of oats, 1 bushel of winter rye and 5# of Appin Turnips.

This mix works well flown into standing corn or drilled right after the corn harvest.  I have attached a You Tube video to show the wonderful benefits cattle producers can get using this cover crop.

How deep can radish roots go?

GroundHog Radish at 6 weeks 001
I imagine that the finer roots went deeper than 15"...and maybe much deeper from what I am learning!

After 6 weeks my GroundHog Radish is around 12″ deep and 1″ in circumference at the top.  How deep can radish roots go?  Because we need to know things like that I have been doing quite a bit of research.  The attached chart shows how deep some radishes can go…over 4 feet deep!  WOW!

http://www.soilandhealth.org/01aglibrary/010137veg.roots/010137ch17.htmlRadish Root depth
Research done in the 1950's shows Early Scarlet Turnip White-tipped radish roots can go over 4' deep!

Radish Plot Report from June 26

Radish plot 013
This is is the variety I called "Stubby" in the previos post...it's very shallow rooted versus the other varieties in the test. Let's hope that this is not the variety that someone sells as "Big Bubba" Radishes for your cover crops!
Radish plot 006
This variety was among the deepest rooted in the trial.

I planted a cover crop Radish plot over Memorial Day Weekend (5/29) in my garden plot.  I have 5 varieties in the plot from around the world.  My goal is to see what differences there are in the different Radishes being sold in the USA for cover crops.  I replicated the plots so that each variety would be in 2 times with one variety as a check in each of the 4 rows.  My children and I did some plot work on June 26, 4 weeks after I planted the plot.  We thinned out on rep so that there is approximately 4″ between the radishes.  The other two reps are thick…too thick actually, but I want to show what happens at an approximately 12#/acre rate (as some seed company folks recommend).  When thinning the rep I measured the roots of each variety.  BOY, what a difference I found!  Two varieties  have around 8- 9″ deep roots.  two varieties have around 4-6″ deep roots, while one variety has 3″ deep roots.  Now, when purchasing a VNS Radish you might get any of these…or all of them mixed together.  I am also testing these varieties because companies want to sell these on the market as deep rooted cover crop radishes.  They will be called “Big Bubba” Radishes or something like that, but buyer beware.

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.

Cover Crop Radishes – differences in varieties

On May 29th I planted 6 different cover crop radish varieties in a plot.  In those 16 days we’ve had good moisture, and I did apply some 30-0-5 fertilizer around 60 days ago (with slow release N).  I had to thin the plots to have 1 radish per 4″ (recommended distance between radishes by those who seem to know those things).  I am doing this experiment for three different Oregon companies that sell cover crop radishes.  I have this same experiment going on in Michigan, central Indiana, and NW Ohio.

The goal…to identify the “best” cover crop radish.  I hope that by planting in spring and late summer,  we will be able to choose the radish variety/selection that works best for cover cropping in the Midwest.

I brought 4 varieties up from the plots to show the differences after 16 days.  2 varieties have nice long tubers already.  The other two have some catching up to do!  I have a feeling that they never will.  I’ll keep you posted!

Radish plot 016
cover crop radish plot...16 days old (and needing weeded!).
Radish plot 017
4 different varieties of "cover crop radish." 1 on far left I'll call "Stubby;" 2 just to the left of the stick look promising so far; 1 just to right of the stick I'll call "Shorty;" and the far right selection also looks very promising. all 16 days after planting.