Tubers tested for ability to tap nutrients, aerate soil

Deep tap roots increase available nutrients for next year

MEDICINE HAT, Alta. — Scott Lehr is trying to solve a soil compaction problem. He’s experimenting with tillage radishes to see if that problem can be solved without dragging out the iron.

Lehr, who farms north of Medicine Hat, planted 300 acres of tillage radishes this year along with winter wheat and triticale.

“Because we’re silaging this land, there are manure trucks on it and we’re grazing cattle on this land all winter, I’m getting a bit of a compaction issue, so I’m hoping that these will break up that compaction so I don’t have to go in with some sort of deep tillage device,” he said during the Farming Smarter conference in Medicine Hat, Alta., Dec. 5.

It’s the first time Lehr has tried the crop, which is new to Western Canada but more widely used in the United States.

“They seem to grow quite well,” he said.

His cattle are grazing winter wheat and the radishes, though they seem to prefer the former.

“We’ll see in spring how it turns out,” said Lehr. “If I get a yield boost, it will be a bonus.”

Patrick Fabian of Fabian Seed Farms in Tilley, Alta., said 10 southern Alberta farmers planted the crop this year on less than 2,000 acres. He is eager to see whether they get a yield response in 2013 on land now seeded to radishes.

The U.S. data he uses in his sales pitch suggests a five to 10 bushel yield increase on soybeans planted on radish acres. Corn yields increase by 10 to 20 bu. per acre and wheat by seven to 10 bu., he said.

The rationale is that the deep tap-rooted radishes will pull nutrients from depths unavailable to most cereals and oilseeds.

Subsequent crops can use nutrients that are now closer to the surface once the radishes winterkill and the tubers begin to decompose. The tubers and roots also break up the soil and improve water infiltration and soil tilth.

“Is it magic? No, it’s not. It’s just common sense,” said Fabian.

“It’s pulling the nutrients from down below so you’re basically supplementing your crop with additional nutrition. So basically you’re making a withdrawal from your investment account.”

Investment it is, at $3.45 per pound and a recommended seeding rate of three to six lb. per acre.

However, Fabian said it could provide savings on fertilizer or deep tillage equipment.

The radishes are ideally seeded after July 1 by a Valmar or aerial seeding into existing crop. They can also be planted with fall cereals.

Three consecutive nights of -9 C will kill the radishes. Cattle or sheep can graze the tops, and decomposition will release the stored underground nutrients when the ground thaws.

Fabian said radishes can also be a good hedge against soil erosion on sandy land in wind-prone areas.

“There’s a whole host of benefits here and the neat part is, we’re not looking at something that’s a whole new technology that we have to buy iron and equipment for,” he said.

“Conventional seeding equipment works just fine.”

Radishes are members of the brassica family and subject to the same pests as canola. Fabian said later seeding allows them to grow when most pest issues are less severe.

He is planning an experiment on one of his fields this spring in which he will plant radishes with a Valmar on a cereal crop after herbicide spraying. His GPS tracks 90 feet, and the Valmar is 40 feet, so any differences in subsequent crop should be obvious.

“I’m really looking forward to that.”

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