Photo: No-till planter cutting and planting through cover crop residues
Have you ever wondered what goes on down at the farm when the cash crops come off the field? Every operation manages their field a little differently depending on whether this year’s crop is corn, soybeans, vegetables, or blueberries, for example. Regardless of the type of crop, a farmer has a choice on whether to leave their fields barren until the next crop or growing season or invest in their soil. One conservation practice that New Jersey Audubon’s Stewardship Department has been working with farmers to adopt across the state to help protect and support their soil health is cover cropping.
A conservation practice is an activity that protects or reduces important natural resources, like soil, water, plants, or animals. A “cover crop” is a type of conservation practice where an annual plant is seeded after a farmer’s cash crop is harvested, rather than leaving fields without any cover or plant material. It creates a blanket for the soil, which protects soil quality, water quality, and can even create temporary wildlife habitat. Cover cropping typically requires little to no inputs after seeding, including irrigation, fertilizers, etc. To reap the full benefits of this practice, farmers leave the cover crop in the ground from the time of planting right up until they are ready to terminate it to plant their next cash crop, rather than harvesting the cover crop for income. Each farmer has their own reason for planting cover crops year to year, as they can serve several purposes including, but not limited to, reducing soil erosion; reducing sedimentation and nutrient runoff to waterways; building soil health through the addition of organic matter; improving soil structure and water infiltration; breaking compaction; reducing weed, pest, and disease pressure; and providing resources for wildlife.
Some plant species are better suited to address certain resource concerns than others, so there is no one-size-fits-all cover crop. Sometimes, a mix of different cover crop species can be tailored to each farmer’s operation based on their need to treat several different concerns on the farm. Selecting cover crop species to plant also depends on the time of year a farmer is planting the cover crop, as there are several different warm season plant species for spring and summer cover crops, and several different cool species for fall and winter cover crops. For instance, if a farmer is mainly concerned about erosion control over the winter when rain and wind levels are relatively high, annual rye would be a great cool season species to plant as it is a grass that can provide thick coverage protecting the soil surface from erosion. But if the farmer is concerned about erosion, compaction, and depleted organic matter, a good cool season mix to plant would be rye for erosion protection, crimson clover for adding nitrogen and nutrients back into the soil, and daikon radish for breaking up compaction. Similarly in the summer, if a farmer wants to give their ground a rest and build up soil organic matter and structure, they might plant a sunnhemp cover crop. If they have an additional concern of treating weed pressure over the summer, they might add buckwheat to their mix as well.
Remember, the farmer never removes the cover crop from the soil. When they are ready to plant their next cash crop, they will complete “termination”. “Termination”, or killing the cover crop, can be carried out in several different ways. Some cover crops terminate on their own via what’s called “winter killing”, where the winter temperatures get cold enough to kill cover crop species on their own. This can be very advantageous for a farmer as it reduces the number of passes they need to make over a field via the following intervention methods. Disking or tillage are mechanical methods often used to terminate cover crops and incorporate their biomass into the soil, especially on vegetable farms and others using conventional tillage for field preparation. Disking and tilling involves turning over or plowing up the soil. Herbicide application is another termination method commonly used by no-till operations. After the chemical is applied and the cover crop is killed, their specialized seed drills can cut right through the cover crop residue left on the soil surface when they want to plant their next crop. The residue acts as a mulch layer which provides weed suppression and protection from erosion. No-till operations do not use planting practices that till or plow up the soil to avoid soil erosion and weed infestations. Another mechanical termination method, called roller-crimping, can be used for termination as well. This method works by rolling over fields with a large, heavy, ridged rolling pin-like tractor attachment that lays down and damages the base of each plant enough to kill it therefore creating a mulch like layer for no-till operations. Cover crops may also be biologically terminated by grazing livestock over fields. The lifecycles of cover crop species and timing of control measure plays a large role in the success of termination. If termination, regardless of the method used, does not take place before the cover crop sets seed, it can re-germinate while a cash crop is in the ground and become a weed issue itself throughout the growing season.
In addition to the challenge of perfectly timing termination, cover crops can also be seen as a risk to farmers in that, even though they are typically not irrigated or fertilized, they are still plants that require moisture and nutrients for growth. Some farmers are concerned that, in times of drought, the cover crops may “use up” naturally existing water and nutrients within the soil profile leaving it deficient of those resources for the cash crop that follows. When used in conjunction with other conservation practices that benefit soil health, this is often not a worry because water conservation and soil nutrient retention is already occurring. Another common hesitation with planting cover crops is that they are perceived as an added expense to farmers because they aren’t profiting from them directly. However, there is an indirect monetary profit via increasing productivity of soils and therefore reducing the need for expensive inputs (like purchasing fertilizer) and increasing crop yields. Lastly, farmers can receive cost-share to help offset the cost of purchasing and planting cover crop seed through the USDA and North Jersey RC&D.
New Jersey Audubon provides technical assistance to farmers interested in implementing cover crops and can help them design the appropriate seed mix to treat their resource concerns, decide on the appropriate timing of the seeding, termination type and best seeding rate. New Jersey Audubon has hosted several outreach events and networking opportunities for farmers interested in cover cropping and other conservation practices, which have provided opportunities for their peers to share stories of success, failure, trials and tribulations, and assist one another in making the best decision for them and their farm.
For more information on cover cropping in New Jersey, contact Alyssa Bright, NJA Stewardship Specialist- Agriculture & Wetlands at [email protected]
Photos and Blog by: Alyssa Bright, Stewardship Specialist- Agriculture & Wetlands
