This morning, I received a timely question from a a farmer in New Jersey: “Is the ‘Tillage Radish’ that is protected / copyrighted a better product than say, Forage Radish from Fedco seeds?” Good question, and I had just been ruminating on the need to write about some critical details of how to get cover crop seeds and the best way to put them in the ground to prepare for no-till vegetables next spring.
Forage radish (Raphanus sativus L.) varieties
Researching forage radish and oilseed radish in the early stages of research at the University of Maryland (ca. 2004).
In our research at the University of Maryland, we have used Tillage Radish from Cover Crop Solutions. This is largely because the research evolved in collaboration with Steve Groff, the proprietor at Cover Crop Solutions. Tillage Radish is a patented brand, ensuring the quality from seed to seed and lot to lot. We are not in any exclusive arrangement with Tillage Radish, however, and we’re always investigating what’s out there, and what’s best for farmers in terms of production and value. Last fall, we did a trial with five varieties and found comparable results among all of them in terms of biomass production and N capture. This is not to say they are all the same… Graza radish has been bred for grazing and generally winterkills at colder temperatures. Good for further north, but perhaps not a good choice if you’re in the “border” states for winterkilling like Maryland.
Seed dealers
We have heard horror stories of farmers getting “forage radish” seed that turned out to be puny red salad radishes. These days, there is much more awareness of forage radish and it is unlikely something like this would happen, but it’s always worth buying from a reputable dealer. Walnut Creek Seeds in Ohio carries a few radish varieties and Ann Brandt is very knowledgeable about all of them. (They also carry phacelia if anyone is still interested in trying- I seeded some yesterday!!). The only dealer that carries organic forage radish (Tillage Radish) is Albert Lea Seeds. Don’t tell your inspector I said this, but for most growers, there are plenty of legitimate (as outlined by NOP) reasons why you don’t need to buy organic radish seed, so don’t strain yourself trying to do it. If you’re a dealer and you feel left out in this post, please make a comment and I can keep updating it– we’ve no intention to be partial, but want to give people information about where to source seed.* Managing Cover Crops Profitably has an appendix with cover crop seed sources.
Wildlife seed vs. cover crop seed
Before winterkill, deer enjoyed some radishes (look closely) but left plenty for the soil.
In my quest for cover crop seeds, I have ordered seed from various wildlife seed plot dealers. This can be a great way to get smaller amounts of seed. It is usually more expensive (per pound), but otherwise you may be stuck getting a 50 lb bag (see above note about Fedco, which carries 2 lb bags). It makes no difference whether they’re marketed as cover crops or wildlife crops, many of these plants are indeed tasty to wildlife. That’s just a side note that might deserve a post later. I can’t vouch for specific companies here, but just talk with the dealer and make sure you’re getting what you want. Cover Crop Solutions has also started selling smaller quantities of Tillage Radish on Amazon.
I am also an option for forage radish seed. If you want to try forage radish for no-till spring vegetables, get in touch with me and I can send you a couple of pounds of seed in exchange for some feedback. (While supplies last!).
Other cover crop seeds
Just a couple of notes about other cover crop seed. I’ve heard from the high-residue folks that it’s best to get specific varieties–not “variety not stated (VNS)”–of cover crops like hairy vetch. The reason for this is the need to minimize variability in maturation for mechanical termination. Another thing to discuss with a seed dealer.
Putting seeds in the ground
An Earthway seeder can be a mini drill. You can gang up several for efficiency.
If you’ve got a drill already, this part isn’t for you. Drills are a great, easy way to seed cover crops, usually enabling good seed-soil contact. For drills, the optimal radish seeding rate is 6-8 lb/acre. If you’re working on a smaller scale, seeding cover crops can be more vexing. Mark Schonbeck and Ron Morse have put together a great factsheet on seeding cover crops in small-scale systems. An Earthway seeder can be a great (and not that slow- really!) way to seed cover crops effectively. If you get annoyed by seeds getting caught behind the plates (and crushed), you can do an easy modification. Last year, I seeded an entire experiment with a single Earthway. The only criticism I have is that there is very little flexibility in the seedplates that come with it. The radish seedplate works ok for forage radish seed (8″ rows), but it uses more seed than other methods and can result in stands that are a little too thick. If you make the rows any wider, you risk losing some weed suppression. Remember- the forage radishes are edible, so you could always harvest some for market or yourself and let the others grow bigger.
Prior to seeding forage radish, it’s important to have good weed control. For most organic growers, this means some light tillage. Yes, this goes against “no-till,” but without spraying, it’s difficult to control weeds year-round. So, the tillage in this system occurs right before cover crop seeding, and then tillage is skipped before cash crop seeding in spring. With a very close mowing and a no-till drill, it would be possible to establish forage radish without spraying or tilling in a field without significant perennial weed pressure.
Monitoring forage radish as it grows
Despite the appeal in a silver bullet, forage radish is not one. There are plenty of things that can go “wrong,” leading to conditions that are not favorable for no-till seeding without herbicides in spring, but if you’re careful about seeding early, getting good seed-soil contact, making sure you seed at the right rate, and perhaps even irrigating, you should get good results. Below are some of the reasons for poor results.
Inadequate residual soil nutrients.
This sandy field in Maryland after wheat did not have enough residual N to support a productive forage radish crop (photo taken in mid-September). In this situation, overseeding with a legume is recommended and no-tilling without an herbicide in spring will not be possible.
Uneven stands
Where the radish is planted less thickly, it is visibly bigger and greener, but there is also bare soil visible. Where it is too thick, the competition between plants is too much. The right seeding rate is important for optimal growth and weed suppression. 5-8 plants/square foot is ideal.
Lack of water
Like all other crops, forage radish needs water to germinate and grow. Don’t be scared to put the seed over an inch deep if that’s where the moisture is. And, if you’ve got the ability, irrigate it. Irrigating can turn a spotty stand (above) into a fantastic stand. Farmers have told me they wish they’d irrigated their forage radish.
Get in touch if you want seeds or have questions.
