Healthy soil and sustainable growing

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University tests show radishes good choice for cover crops
http://www.theprairiestar.com/articles/2009/10/12/ag_news/farm_and_field/field1.txt

By TERRI ADAMS, The Prairie Star
Friday, October 9, 2009 3:34 PM MDT
Radish tap roots can be 2 to 3 inches in diameter, as seen in this photo, and 
extended almost 2 feet into the ground. That root system breaks up soil 
compaction and increases deep water penetration and storage. Photo courtesy 
of Steve Groff.


Even though the window for planting cover crops is closed, it's not too early 
to take a look at a new option for next year.

Tests at five different universities show radishes offer more soil benefit 
and require less work from the producer than all other standard cover crops.

According to Steve Groff, partner at Green Tillage and CEO of Steve Groff 
SEEDS, LLC., radishes are gaining the attention of farmers around the 
country, and deservedly so.

Groff first noticed radishes when the University of Maryland began testing 
them as a cover crop on his farm back in 2001.


“I was amused at first but then I saw what they did for the soil,” said Groff.

He went to the UM research team, led by Dr. Ray Weil, and asked where he 
could purchase radish seeds for his own use and was informed that the best 
varieties for cover cropping were hard to get. They were not commercially 
available.


As with most intrepid farmers, a light went off in Groff's mind.

“We were able to get some seed and started propagating it and expanding it.” 
When they had enough seed to sell, they began marketing Tillage Radishes.

Since then sales of Tillage Radishes have doubled every year.

As farmers hear and see the results they are starting to plant radishes in 
their own fields, either as a stand alone cover crop or with cover-crop mixes.

“That's the next generation of this -cover-crop mixes or cover-crop 
cocktails,” said Groff. “It's not a fad; it's a trend and radishes are on the 
leading edge of that right now. Producers are saying radishes go in every 
mix.”

Ken Miller, who works with the Burleigh County Soil Conservation District in 
North Dakota and farms south of Mandan, N.D., agrees.

He has seen radishes work in his job and also on his own farm. In fact, he is 
now putting radishes in all his personal cover crop mixes.

“Even though they are a cool season crop, you can plant them with warm season 
mixes as early as July,” he said. “They stay in the canopy until September; 
then they really start to go.” He said radishes seem to thrive in cold, 
dryland areas like those found on the Northern Plains.

Groff agreed. “They really like the cooler weather,” he said.

Radishes also help improve water penetration. Most plants send out fine, 
hair-like root systems. According to Miller, “the radish gets a very deep tap 
root. In 45-60 days you can get a root that is 2 to 3 inches in diameter. The 
root tapers off at about a foot and a half and then sends out a very fine tap 
root that can go down to 5 feet,” Miller said.

That opens large holes in hard, dry soil; allowing for optimum and deep water 
penetration and storage and helps aid in the aeration of the soil, breaking 
apart compaction.

“They are the best plant I've seen for going through a hard layer of soil. 
Most other roots will hit a hard layer and then turn and go horizontal. Not 
radishes. They are aggressive that way. They will find a crevice and keep 
growing down.”

Groff said that those thick, long roots are also unique for another reason.

They scavenge all the nitrogen they can find, either from the soil or 
chemical applications, and store it in their root system until spring time.

Then, when it begins to thaw, the roots decompose. As they decompose they 
release all that nitrogen back into the soil, loading the soil with the vital 
nutrient just in time for the next season.

“A lot of these other cover crops, like rye grasses, when they decompose the 
nitrogen is used up by the microbes and they are only able to give it back 
incrementally. Not radishes. They give it all back,” Groff explained. “We say 
it's like a bank account. You invest nitrogen in it and then you get it all 
back in the spring with interest. The interest is that the radishes have also 
broken up and opened the soil, provided organic matter, and will increase 
crop yield.”

In multiple university tests those crop yield increases have run from eight 
bushels per acre to 41 bushels an acre in one corn test.

For colder climates, Groff says producers should consider planting radishes 
as a cover crop from mid July to the beginning of September. Producers should 
try to plant them no later than four weeks before the first killing frost.

When used as a stand-alone cover crop, radishes are seeded at a rate of eight 
pounds per acre. If radishes are seeded in a mix, the rate will be lower. 
Currently the price is $3.10 a pound without quantity discounts.

“We just mix everything together, the big seeds and the little seeds and put 
it all in our drill and go,” said Miller.

Once seeded, radishes germinate rapidly.

“Four days is what it takes,” said Groff. “We even had one farmer tell us his 
were up in three days, but four days is average.”

Once up, radishes grow rapidly, covering the area and suppressing weeds. They 
will continue to grow until a hard frost.

“Even if you have nights that get down into the teens, they're fine if the 
days warm up to the 50s and 60s. They like cool weather so it takes several 
nights down in the teens to stop them,” he said.

Once stopped, radishes overwinter in the soil, reducing wind erosion and 
trapping needed snow. In the spring, as the ground begins to thaw, radishes 
decompose on their own. No need to spray or disc the ground.

Miller said they decompose rapidly. “This is all done no-tillage,” he said. 
“You seed directly into the crop residue in the fall and in the spring they 
decompose on their own. You don't have to work to get rid of them. We call 
them the ripper crop because they eliminate tillage.”

Miller said there are many benefits. Cattle can graze radish tops from winter 
fields.

Radishes also “help feed the soil and get it in balance. It's a great 
fertility program and you get a tremendous crop response the following year,” 
he said.

Producers who are interested in learning more about Tillage Radishes can go 
tohttp://customers.clarycommunications.com/m/b7aGd05OJnKYjdebIGj1RC4YDzgnkN18cXqjTCL98Qr7narocg
 or www.tillageradish.com.