Steve Groff has been experimenting with tillage radishes on his farm to find out how they impact wheat yields. The Holtwood, Pennsylvania, farmer says tillage radishes are a special form of radish. “It is a trademark name for the best radish selection found for use as a cover crop,” he says. “There are many other radish names out there that may or may not be tillage radishes.”
Tillage radishes are beneficial when used as a cover crop because they are generally unique to the soil. “They are a brassica. They are a different species that most farms have seen,” says Groff. “I think that alone is why they are doing so well. You are introducing a different species into the soil.” The new species affects the biology of the soil and can “wake up other critters in the soil,” he says. “We have tested calcium in the leaves in the radishes, and there is twice as much in the radish as in cereal rye. They have a great ability to pull up nutrients.”
Tillage radishes decompose quickly in the spring and release the nutrients, especially nitrogen, they have stored up into the upper portion of the soil. The radishes take in extra nitrogen from the soil and release it after they are killed off. The wheat then takes up what it needs to grow. Groff says this helps the succeeding crop by having the nutrients where they can be reached. “All of these components lead to higher yields,” he says.
An early application of nitrogen can wipe out the tillage radish affect, cautions Groff. Although this is the trend right now, Groff says further testing needs to be done to confirm it.
Groff saw the effect tillage radishes have when planted with wheat when a farmer accidentally forgot to clean out his drill. The farmer had planted a couple acres of tillage radishes and wheat at the same time. Groff reported he saw an 11% increase in his wheat yield where the radishes were planted. The farmer tried it again along with a few other neighbors, and each saw an increase—up to 18%—in their yields.
Replicated testing shows a five to 12 bushel per acre increase in wheat when radishes are in the mix.
By mixing 2 pounds of tillage radish at about $6 per acre, Groff says he can easily recoup his input costs in about 2 bushels of wheat. “There is no extra trip across the field, just a little bit extra time taken to get the radishes mixed,” he says. “It’s so easy and cheap, it needs to be tried.”
Currently, several farmer and university plots are being tested to see if mixing tillage radishes and wheat will work across the country. In Ohio alone, 80 farmers are running side-by-side comparisons to see what the trends are. “We want to learn why this works better sometimes than others,” he explains.