by Sonja Heyck-Merlin
Have you ever spotted a farmer wearing a “Don’t Farm Naked” T-shirt? Rather than alluding to nudity, it’s a proclamation to the importance of cover cropping. Vegetable growers report, however, that their increasing use of cover crops is posing some challenges. Chad Cochrane, a New Hampshire-based USDA-NRCS resource conservationist, and a group of Northeast growers discussed these challenges and some solutions at a New Hampshire Vegetable and Berry Growers’ Association roundtable.
Cochrane summed up the challenges: “You’ve gotten so good at growing cover crops that now you’re trying to figure out how to terminate and work around them. I always encourage people when they’re thinking about cover cropping or trying something new – new species, new timing, new seeding methods – to really think about how you’re going to kill it on the backend. Cover crops need to die or else they’re going to be a thorn in your side.”
For winter rye, growers said they typically flail mow the cover crop (some in both directions) in early spring and then plow and/or disc the residue under. This practice is effective at killing the cover crop, but if the ground is excessively wet, it can be impossible to get heavy equipment on the ground at the right time. On the contrary, Cochrane said that in drought conditions, growers may let their cover crops grow too long and steal too much moisture.
“I think sometimes we try to push the envelope as far as we can, but if it’s getting wet and you think you’re getting to a point where you might not be able to get onto the field, or it’s getting so dry that cover crops are stealing your moisture, I would just err on the side of terminating a little earlier than you want to,” Cochrane said. “If you can’t grow your cash crop you’re in a pretty bad place.”
Some farmers avoid winter rye altogether, instead using oats and peas, which winter kills. One grower said that to incorporate oats and peas in spring, they use a chisel plow followed by a Perfecta field cultivator. Then they will shape beds or direct seed directly behind the cultivator. According to them, this practice supercharges their soils, providing lots of extra organic matter and some nitrogen. By eliminating the need to plow or disc, as is customary with winter rye, they feel they are better maintaining their soil structure.
Some growers continue to plant winter rye because they’re able to plant it later into autumn, and they have found success in killing it with specific types of tillage equipment. In addition, they said a spring-style harrow can be added to their disc gangs, allowing growers to get on rockier ground and potentially have more movement in the gangs than with a straight frame. The downside to these disc models is they are very heavy and require a lot of horsepower.
Despite tillage, some growers reported frustration with cover crop residues impacting their transplanters. The top six inches of their soil are clean, but the cover crop residue still lurks underneath.
Cochrane said growers with these issues may be able to attach row cleaners in front of the furrow openers to their transplanters. Row cleaners are customary on no-till planters, working to clear residue and lightly till the planting zone, which helps to improve soil to seed contact. He advised, “Get row cleaners that float. Instead of being rigidly attached to the row unit, they’re on a hinge.” Floating row cleaners move with the contours of the soil and maintain better soil contact. They also avoid digging a trench in front of the row unit and won’t jostle the planter when hitting stones.
Growers may also consider water wheel transplanters, which have coulters that create furrows in the soil. They’re more labor intensive, according to Cochrane, but because human hands are used to set the plants in ground, people can simply work around any residue.
Finally, Cochrane advocated for alternatives to winter rye, such as wheat and barley. “Wheat is another hardy winter grain, and it grows about half as tall. It also matures later, so it gives you some more flexibility,” he said. Because of a general lack of availability of cover crop seeds, Cochrane said growers should contact their seed dealers mid-season.