Frost-seeding: Seeding a cover crop into an established crop in late winter to very early spring. Example: Seeding red clover into wheat in March.
Here are a few helpful hints:
Drilling: This is another good cover crop establishment method, as most drills are equipped with a legume/grass seed box. Drilling works well for metering small seeds (use the standard drill box for larger seeds) and gives good placement and seed-to-soil contact. Drilling can be especially successful in no-till management systems.
There are many variations on these methods. Watch different equipment in action on farms and at farm shows. Every piece of equipment is different, and individual farm needs depend on the management system in use.
Broadcasting by ground: This is the most popular and accurate seeding method and may be done using spinners, drop tubes or air pressure. The most critical factor is accurately metering seed before it is spread. Make sure the seeding pattern is appropriate for complete and even ground cover. Different seeds have varying spread patterns based on their respective weights, and heavier seeds spread further than lighter seeds. This can cause difficulties when heavier and lighter seed mixtures are applied. Broadcast seeders may be mounted on ATV’s, tractors, tillage tools or other implements.
Broadcasting by air: Cover crops can be applied from a broadcast seeder mounted on an airplane. This practice works well for larger seeds like rye and wheat, but is not recommended for small clover or grass seeds. Broadcasting by air allows for the overseeding of an existing crop or for planting when soils are too wet for ground seeding, although seed germination might be slower and a higher seeding rate may be needed.
Start by choosing a cover crop and a method for its application (see specific cover crop information sheets for recommendations). Some methods and equipment might include:
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The Michigan State University Extension cover crop team is releasing several videos to help farmers incorporate cover crops into their cropping systems. The videos provide overview of different topics and suggested recommendations for successful establishment. Below are videos on “Seeding Equipment for Cover Crops” and “Calibrating a Drill for Cover Crop Planting.”
If you would like to learn more about cover crops, how they can benefit your farm, or to find a cover crop educator, visit the Michigan State University Extension, MSU Extension Cover Crops website.
The most common seeding method is drill seeding. This is the most often used reliable method because of seed placement and good seed to soil contact. A second method involves using a row crop planter. Row crop planters usually result in the best cover crop establishment due to the good seed soil contact, depth control and consistent seed spacing. Other methods include broadcast with or without shallow tillage, slurry manure seeding and frost seeding.
These are all factors to consider for successful establishment of a cover crop.
Farmers can choose from a number of methods for seeding cover crops. Just like selecting the best species or mixture, selecting the seeding method that is best suited for your operation is one of the keys for successful cover crop establishment. When selecting a seeding method, consider your establishment window and answer the following questions:
Previous studies have shown that cover crops in eastern Nebraska usually have greater productivity when they are established before harvest than drill-planted after harvest. Cover crops with more biomass will better reduce erosion and run-off. High amounts of cover crop biomass mean more organic matter is returned to the soil.
Table 1 contains cover crop management and sampling dates. For rye, seeding rates (pure live seed) were 60 lb/ac, 90 lb/ac, and 120 lb/ac. Hairy vetch seeding rates were 40 lb/ac, 60 lb/ac, and 80 lb/ac. In the fall, we determined cover crop stand counts by counting the number of plants in two 5×1 ft frames in each plot. In the spring, we measured productivity by clipping biomass in two 5×1 ft squares per plot, drying and then weighing biomass (see table 1). We used analysis of variance to find statistically significant differences (α = 0.05).
When it comes to selecting a seeding rate for broadcasting cover crops, there is little research-based information. Broadcast seeds do not have good seed-soil contact which reduces the seeds’ ability to take up water necessary for germination. Thus, stand counts of broadcast cover crops are often lower than those of drilled cover crops. Could increasing the seeding rate overcome low stand counts and improve cover crop productivity?
With increasing seeding rates, seed costs of course increase. Table 2 shows the cost of seeding each cover crop at the three rates – while rye is one of the most inexpensive cover crops, hairy vetch is much more expensive. Considering the cost, it is important to give it optimum conditions for success, such as planting it early and inoculating the seed.
Despite low emergence, cereal rye was a productive cover crop when established by late-season broadcast interseeding. When broadcast interseeding cereal rye into corn, we found that a seeding rate of 90 lb/ac produced the most biomass in the spring. When broadcast interseeding into soybean, a seeding rate of 60 lb/ac produced the same amount of biomass as higher seeding rates. Vetch biomass production was low and was the same at the seeding rate of 40 lb/ac than at the higher seeding rates. Vetch needs to be established earlier than the mid-to late September seeding dates in our study.