White radish: It's hot stuff as a cover crop 2012.01.18

Written by David Green. Posted in Feature Stories

By DAVID GREEN

radish rootIt’s the latest greatest thing in cover crops, says Nathan McNett, a soil technician with the Natural Resources Conservation Service office in Adrian.

He’s talking about what’s known as the daikon radish in the Far East where the root crop is eaten.

Here in the corn country of Lenawee County, the daikon is called white radish, oil-seed radish, fodder radish, groundhog radish or forage radish.

It’s also commonly known as the Tillage Radish, but that’s a trade name owned by a Pennsylvania company that claims its radish is the best.

Although it’s been used as a cover crop in parts of the United States for several years, this marks the second year of planting in Lenawee County, as far as McNett knows.

McNett isn’t surprised by the growing popularity of radish because the benefits are many.

“It seems to be really great,” he said.

While most people might picture the radish as a small round root crop enjoyed from the summer garden, the white radish produces a long tuber that can easily reach a foot in length and several inches in circumference.

All that organic matter enriches the soil and releases nitrogen. The tap roots can grow several feet deep, and the main body of the radish bores a good size hole into the soil.

It’s adding organic matter and breaking up soil at the same time, McNett said, and with heavy equipment operating on fields, soil compaction is a problem for many growers.

The crop’s root system can alleviate the need for deep tillage, and as the roots decompose, channels are opened in the soil that a subsequent crop can take advantage of. The process is know as “bio-drilling” and it improves root access to subsoil moisture. The result is a more resilient crop if drought conditions arrive.

“When the radish rots away, it leaves a gaping hole,” McNett said, “and that lets a lot of water in. We hope it will allow equipment to get in the field earlier.”

There’s no need to cultivate the radish in the spring because of its quick decomposition and that’s going to lead to a reduction in fuel used.

Researchers have looked at the allelopathic characteristics of the radish—biochemicals produced that suppress the growth of other plants. The radish has been found to interfere with the growth of some weeds even after it’s died off over the winter.

According to University of Maryland soil science professor Ray Weil, the radish takes up nitrogen and other nutrients from both the topsoil and deeper soil and stores it in tissues near the surface. This makes nitrogen available for the next crop, he said, and also prevents excess nitrogen leaching into groundwater during the off-season.

So much for the subsurface work of the radish. There are more benefits on top of the ground.

When planted in the early fall, the radish quickly forms a dense canopy that suppresses weeds and this leads to a savings on herbicides and cultivation.

Compared with traditional cover crops or winter weeds, the radish allows seedbed soil to warm and dry out faster in the spring.

The canopy of the radish helps prevent soil erosion when the plant is growing, and after it’s decomposed, the holes left behind collect rain to trap sediment before it leaves the field.

Research is pointing toward increased crop yields in many cases where radishes are grown.

Just north of Morenci, Gary Gallup of State Line Farms has radish planted in rows, but some growers fill in the empty space with winter pea or another cover crop.

McNett said a few test plots were grown last summer at the Raymond-Stutzman Farm that involved radish mixed with other crops.

McNett wanted to get some personal experience with the radish and planted a few in his garden. He’s looking forward to the benefits of bio-drilling in the compacted soil of his own back yard.

Gallup wonders how many people are enjoying the radishes he has planted along M-156. Cars are occasionally spotted off to side of the road, with someone in the field investigating the odd-looking vegetable.

“We had one for our Thanksgiving dinner,” Gallup said. “It tastes just like a regular radish.”

There will be an odor

Among the multitude of benefits of the white radish, there’s one characteristic that might not be enjoyed. When the weather warms after the winter kill-off, there’s going to be an odor. The decaying plant gives off a sulphur smell.

Last year in several areas of Ohio, fire departments were getting calls to investigate leaking propane. The searches proved futile until the real culprit was found.

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