When Columbus left the safety and comfort of his home to find the New World, people thought he was crazy; everyone knew the world was flat. Instead of finding India, Columbus found North America. Not what he was looking for, but a remarkable discovery. What does Columbus have to do with agriculture? Products that were developed for one market can be a remarkable solution for a different problem. Tillage radish is one of those products.
In 2001 Steve Groff and Dr. Ray Weil from the University of Maryland started developing tillage radish as a cover crop to improve soil health, break up soil hardpans and control weeds. After years of experimenting, fine tuning, and local agronomic development, Cover Crop Solutions now markets tillage radish as a wonder plant with many uses, widely adapted to different climates.
A cover crop is planted to cover the soil. This practice can manage soil fertility and quality, control pests, create a disease and insect break, control erosion and nutrient loss and provide a grazing opportunity. Cover crops are not common in Western Canada but are used indirectly. Greenfeed crops, annuals used for grazing and green manure crops can be referred to as cover crops. In most cases cover crops are a monoculture, or sometimes two or three crops mixed together. These work, but a true cover crop is made up of multiple species grown together to get the best effect.
Multi-species mixes will include both monocot and dicot (grass and broadleaf) species. Of the broadleaf types, most mixes will try to include pulses and, warm season and cool season types.
The idea is to mimic nature by creating diversity in the stand. This diversity ensures that different parts of the soil will be used, that the stand will be made up of plants that grow to different heights at different times under different conditions, and that there are a variety of effects on the soil.
Pulses will fix some nitrogen, cereals add fibre, and brassicas will scavenge nutrients. But most of these species’ roots tend to colonize only the top six inches of the soil. Enter the tillage radish.
Of all the forage radish line, tillage radish has been selected based on top growth and a straight root that produces good loosening action deep into the soil. Oilseed radishes produce roots similar to canola. The tillage radish produces a “super carrot” type of root, driving down two to four feet and creating root pressure measured at 290 psi. Aggressive top growth allows the plant to smother the ground and choke out weeds.
Tillage radish can be seeded almost at any time after June 20. Seeding after the summer solstice allows the plant to produce more root mass and more vegetative mass. (Corn responds the same way when seeded later than normal for grain production.) For root growth, researchers recommend allowing 40 to 60 days of growth before a killing frost, three consecutive nights of -8 C.
One common concern is seeding into cover crop residue. Because cover crop species should be picked based on compatibility to spring breakdown, most species are well rotted by spring. Tillage radish leaves are mostly basal with high moisture and high protein, leaving a tight carbon-to-nitrogen ratio. This results in a quick rot in the spring.
The roots will dry up, and the root channels left by the rotting tubers will have the appearance of a major gopher infestation. These channels will reduce compaction and allow the soil to warm up quicker. Cover Crop Solutions’ research has shown significant nitrogen and phosphate accumulation in the root of tillage radish. This is released to the next year’s crop as it rots. Next year’s soil will have a lower pH and nutrients will be released slowly, resulting in higher yields.
Once it’s growing, the tillage radish will drive its root down. If it encounters a hardpan, it will send out root hairs. When a root hair finds a crack, it will develop into a root, cracking the hardpan open. Since the Prairies have seen well above average moisture and not much soil frost, there is a lot of hardpan in the soils, limiting crop development and moisture infiltration. Tillage and seeding operations will accelerate hardpan development.
If the goal is to break up hardpan with a pure stand of tillage radish, researchers recommend using seven to 10 pounds of seed per acre. Higher seeding rates are used on heavy soils with good moisture. The goal is to produce lots of small roots to break up as much of the hardpan as possible.
For grazing, a mixture of species is a must. Tillage radish has high feed values, and is high in protein. It’s best to mix in 50 to 60 per cent grass, along with pulses and potentially other brassica species, rates depending on plans for next year’s crop and the animals grazing the mix.
On our farm we saw production of nine to 17 wet tonnes per acre from our tillage radish, seeded at four to 10 pounds per acre on August 1. Root production ranged from five to nine wet tonnes per acre (97,000 to 157,000 roots per acre).
We also had a trial where we broadcast seeded Tillage radish into our standing corn crop after we had a plugged run. We broadcast with a hand-held lawn seeder with no incorporation. The plants covered the ground by freeze-up. Grazing showed fantastic results, and the cows thanked me for doing it!
Research in the U.S. has shown significant yield increases in the years following radish. All published yield reports (from the U.S.) show a five to 12 bushel per acre increase in winter wheat yields when seeded with two to three pounds of tillage radish; a 10 per cent yield bump in soybeans after tillage radish; and, an 11 per cent increase for corn. Lots of places aerial broadcast tillage radish into five to six foot corn. Farmer testimonials seem to support yield increases even under drought conditions.
Tillage radish has potential for grazing, soil improvement, nutrient recovery, weed control, grazing, and erosion control. There is also a human consumption market. Overall, Tillage radish is a management tool with potential for both grain and livestock producers. On our farm, we’ll continue to trial innovative ways to use Tillage radish, helping to improve the soil, increase plant health, and net us more dollars while we reduce our risk and input costs. †