By Kirsten Workman, Heather Darby, Matthew Ryan, and Aaron Ristow (Adapted by SWNYDLFC)

Northeast farms are planting over one million acres of cover crops, and momentum for this conservation practice continues to grow because of its crop, soil, and environmental benefit. Increasing financial incentives coupled with environmental regulations have pushed even more farmers to adopt cover crops. However, like any other crop grown on the farm, the benefits will only be realized with proper planning and timely management.

To make cover crops a successful part of crop rotation, especially in the Northeast, it is important to be creative and adaptable. Cover cropping works the best when it is an integral part of the farm's cropping system, not just an afterthought. With spring knocking on our door, our focus is on the best strategies to terminate winter cereal cover crops. Emphasis is on being flexible based on weather, field conditions, and management goals. The best plan is to always have a backup plan!

SPRING TERMINATION STRATEGIES FOR WINTER CEREAL COVER CROPS IN THE NORTHEAST

EARLY TERMINATION. Early adopters of cover crops may "fear the cover crop" especially come spring! The first impulse is to get rid of it as soon as possible so it doesn't interfere with cropping activities. In many cases if spring conditions are dry, it may be advisable to terminate the cover crop so that soil moisture is conserved for the cash crop. The cover crop begins to grow much earlier than most grass species and will actively remove moisture and nutrients from the soil. Early termination generally results in low cover crop growth resulting in minimal organic matter additions and nitrogen (N) credits. For farmers interested in higher cover crop biomass that still terminates early, consider sowing a winter tender species like oats, radishes or annual legumes that will kill with winter frost.

HARVEST OR GRAZE AS FORAGE. Harvesting or grazing a cover crop for forage provides a measurable benefit and return on a planting investment. In-season nitrogen return is generally minimal when the cover crop is terminated through herbicide application. However, this really depends (flag leaf or boot stage), between one and four tons of high-quality dry matter can be harvested in May, which can be especially helpful if feed inventories are getting low. Target highest fertility fields with the highest seeding rates (think lots of biomass), but don't ruin your soils with compaction if field conditions are not conducive to equipment or livestock - creating compaction and mud. Because a lot of biomass is removed from the field, a N credit is not reaped for the following crop. If manure is to be applied on these fields, applying in fall is best to avoid feed contamination, or it can be a great place for manure between cover crop harvest and cash crop planting. With increased total crop N removal, higher annual application rates in the nutrient management plan can be justified. Be realistic about how many acres of cover crop that can be harvested. Winter cereal grains grow quickly in the spring and can get overmature in a matter of days.

CONVENTIONAL TERMINATION TIMING. Many farmers terminate the cover crop just prior to corn planting (seven to 10 days) or before the stems begin to elongate. There are many advantages to terminating at this time/stage. First, if the cover crop is terminated through tillage, it is easier to incorporate and may take fewer passes through the field. It also is generally easier for most no-till crop to push through the biomass and less chance for the cover crop to impede corn seedling growth. Many farmers select the time of termination based on moisture content of the soil, letting the cover crop grow closer to planting to reduce soil moisture in wet years or terminating earlier if the spring is dry. Herbicide termination too close to the time of planting might cause issues with the planter as the cover crop can become wiry and wrap-up around the coulters and row cleaners and ultimately plug up the planter. Manure can be applied on these fields as soon as field conditions are good in the spring, minimizing losses, but also getting it on soon enough to not impede cover crop herbicide termination.

PLANTING GREEN. Planting corn directly through a living cover crop prior to terminating it has become a popular approach because of the flexibility it allows the farmer to plant corn when the conditions are right without needing to worry about terminating the cover crop first. This maximizes the benefits of the cover crop by allowing it to grow as long as possible without getting overmature. It is often easier for a corn planter to work effectively, as the cover crop is still green and anchored to the soil, preventing wrapping on row cleaners and closing wheels or pinning residue in the furrow. However, once the corn is planted it is important to terminate the cover crop quickly to keep the cover crop from impeding corn growth and development. If the cover crop has elongated and heads are visible or nearly visible, the corn crop may require additional early nitrogen since the cover crop will be slower to decompose and release N. This approach also offers a lot of flexibility for manure applications as manure can be applied anytime from the fall through spring on a living crop, reducing nutrient loss and runoff risk.

ROLLING AND CRIMPING. Cover crops can be mechanically terminated with a process that involves rolling down of the cover crop while simultaneously crimping the stems. This practice is gaining favor as a tool to manage cover crops that have "gone by" and with organic farmers interested in reducing tillage. Farmers are generally striving to terminate the cover crop before it begins to head/ flower to minimize issues with planting of the cash crop. However in wet years many farmers have found it difficult to get in the field and terminate the cover crop whether they have planted green or not. Once the cover crop has fully headed, biomass quantities can be very high and herbicides are less effective. The cereal grain is tall and even if the corn or soybeans are already planted, it can severely impede corn growth and development due to shading and nitrogen tie up. Rolling and crimping the cover crop is a proven method to terminate a cover crop that is flowering and can be done before or after the annual cash crop is planted. Special equipment (a roller-crimper) is required and can even be mounted on the planter. Benefits to rolling and crimping include soil erosion protection, weed suppression, and keeping the soil cooler and retaining moisture during the hot summer months. It does, however, take intensive management and there are many considerations to take into account. This strategy can work particularly well for soybeans and is covered in much more detail in this guidebook: blogs.cornell. edu/scslab/organic-no-till-plantedsoybean-production-guide/.

HARVEST FOR GRAIN, SEED, OR STRAW. Many farmers have been interested in taking the winter cereal grains to produce their own grain, cover crop seed or straw. Growing grain for seed may require additional equipment such as a combine, drier, seed cleaner, and some type of storage. However, it can save the farm input costs and help to diversify the farm rotation. Winter cereal grains are harvested between July and August depending on location in the Northeast. Yields can range from one to four tons depending on the environment. Even at a low yield of 3,000 pounds per acre is enough seed to plant 30 to 40 acres of cover crop. The straw is then available for bedding, feed or to sell off-farm for additional revenue. The crop is harvested early enough to allow for a summer new perennial seeding or a legume cover crop ahead of corn or sorghum the next year. It also opens a summer window to spread manure.