cover crop radishes

Jun 30 2010

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.

Jun 14 2010

Cover Crop Radishes and Turnips…what are their differences?

Radish plot 010 — Cover Crop Radish on top and forage Turnip below. There is quite a different root structure!

Radish plot 014 — Note the number of root hairs on this turnip tuber. It may have more root surface area than the radish.

The cover crop radishes and forage turnips that I accidentally planted in my wife’s wildflower garden just over 4 weeks ago lets me make some observations about the differences between the radish and turnip roots.

The radishes have a fairly “hairless” root that has very quickly reached 7 ” deep.

On the other hand, the turnips are only 4 inches deep.

So which one is better for the soil? Look at the fibrous roots on the turnip. While the turnip is not as deep, I’d estimate it has more root surface area than the radish!

Unfortunately (or fortunately) I planted several radishes and turnips in the front flower garden (sorry honey). But that allows all of us to keep tabs on the differences as the summer progresses!

Jun 14 2010

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.

Jun 06 2010

Cover Crop Radishes – What they do

2009_11172covercropsfall20090124 — Cover Crop radishes drill deep into the top soil. Some claim that they break through the plowpan.

Cover crop radishes are “all the buzz” these days in the cover crop world. Cover crop radishes should have fairly large tubers that penetrate the soil and add many benefits. The main benefits are that they enhance percolation and aeration. Additionally they provide food for earthworms like few other cover crops. It is quite common to find 3-5 earthworms per tuber.

2009_11172covercropsfall20090511 — Larger tubers of cover crop radishes "lift" the soil around them, "building" the soil. Note the smaller radish to the right...it is also an effective soil builder.

The question that many producers and researchers are asking is “how big” do the radishes need to be to be effective? My friend Barry Fisher, NRCS Agronomist in Indiana, leans towards several smaller tubers being better than the “State Fair” type that may be confused for a baseball bat! While the larger tubers make newspaper ads and are great for photo ops, I’m not convinced that they are necessary. On the other hand, the larger tubers do a better job of “lifting” the soil around them. It is not uncommon to find soil built up around the larger tubers at least 1/2″. (See photo)

Old radish hole — A hole where a radish tuber had been. Note the lifted soil!

Cover crop radishes scavenge nitrogen and other nutrients from the soil. To achieve the larger tubers it is important to have good fertility like manure or a legume planted with the radishes. If there are few nutrients to scavenge, the radishes will rarely become very large.

The main benefits of cover crop radishes

Cover crop radishes:

scavenge nutrients from the soil (especially nitrogen).
penetrate the soil, therefore reducing compaction.
enhance soil percolation and aeration.
provide an excellent environment for earthworms.
provide deer and cattle an excellent wintertime feed.
die in the winter (around 25-29 degrees).

Cover crop radishes may also:

increase yields on corn by as much as 9-10 bu/acre (recorded in central Indiana).
reduce soybean cyst nematode populations.
improve control of winter annual weeds (this is usually the case).

When planting cover crop radishes:

Drill 1-3# or broadcast 3-5#/acre for larger tubers.
Drill 3-5 or broadcast 6-10#/acre for more, smaller tubers.
Use improved selections (varieties) for more consistent results.

The main detriments of cover crops radishes