cover crop radishes

Aug 23 2010

Radish planted with wheat (at seeding time) adds yield? There are a bunch of farmers saying “yes, it does!”

While in northwest Ohio in the Fall of 2010 for a manure management field day, some area farmers told me that wheat producers are adding 2-4# of cover crop radishes per acre to the wheat in the drill…and experiencing excellent results.

Some reported gaining 5-7 bushels per acre by adding the radishes. Others even reduced their nitrogen application by 20% and still got a 5 bu/acre increase where the radishes were planted with the wheat versus where there were no radishes.

As one gentleman said, “It is like having a bunch of ‘french wells’ in the field.” The ground dries faster, the radishes scavenge N and hold it until spring…then slowly release the N to the wheat crop in the spring…cool huh? These won’t be the “state fair” size radishes when planted that late, but they will be 5-12″ deep, maybe the size of your ring finger. It’s an idea to consider!

Aug 04 2010

May planted Radish Plot final results 8/4/2010

RADISH PLOT 8-4-10 009 — GroundHog Radish consistently had the larger and deeper tuber of all varieties tested. This photo is from the ~5#.acre seeding rate plot.

RADISH PLOT 8-4-10 012 — 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.

RADISH PLOT 8-4-10 005 — This variety had the single largest radish...but only the one radish was of any size. This was from the ~5#/acre plot.

RADISH PLOT 8-4-10 024 — 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.

RADISH PLOT 8-4-10 007 — 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.

RADISH PLOT 8-4-10 015 — You can see big differences in these two varieties both shown at the ~5#/acre rate.

RADISH PLOT 8-4-10 003 — 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.

RADISH PLOT 8-4-10 023 — Columbia from the ~12-15#/acre plot.

Jul 15 2010

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.

Jul 15 2010

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

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.

Jun 30 2010

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!

Radish Root depth — Research done in the 1950's shows Early Scarlet Turnip White-tipped radish roots can go over 4' deep!

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