Kable Thurlow and Christina Curell, Michigan State University Extension
(Previously published online with MSU Extension – Cover Crops: August 27, 2019)
Cover crops can be a good option for grazing.
Last year, the wet weather during the spring left many fields unplanted. Those fields severed as a great place to seed an annual crop for fall grazing. Best forage yields are obtained when cover crops for fall grazing are planted July up to August 1st in Northern Michigan and August 15th in southern Michigan. After these dates, yield potential decreases as the remaining growing season vanishes. Therefore, we are at the point where they should be planted soon. [Luckily for us here in Ohio, we still have time remaining to get these crops into the ground before yield reducing weather sets it].
Annual cover crop mixtures can make very nutritious and economical grazing crops for spring, summer, fall and early winter grazing in Michigan. Fall grazing is especially beneficial because it can fill the gap as perennial pasture grasses go dormant for winter. Mixes of four or more plant species all planted together at the same time and same depth at a seeding rate total of 28-40 pounds per acre can be economical and nutritious for fall grazing livestock. These same mixes can also act as soil improvers, suppressing weed growth and mining nutrients from deep down in the subsoil and bringing them to the soil surface. With their aggressive growth, they also increase soil organic matter both from the grazing animal’s manure and from the decaying plant’s leaves, stems and roots.
Fall cover crops for grazing work best following a wheat harvest, oat harvest or an idled field. Depending on the species planted, you usually need 70-120 days of growth before temperatures drop into the low 20’s. Plantings made from late July to mid-August turn out the best, given the fact that we are at the end of that window, now is the time to plant those crops. To provide a healthy, nutritious blend, consider a mixture of brassicas, small grains, legumes, and cool season grasses.
If rotating from a sod crop like hay or pasture, weed control is necessary. But if seeding within 10 days of combining wheat or oats, it is not. The volunteer wheat or oat seed that was lost on the ground from the previous crop harvest can become part of the new seeding mix. The risk of insect and disease pressure will increase if the same plants are seeded on the same sites annually.
According to Paul Gross, MSU Extension Field Crops Educator, “On rare occasions deep rooted cover crop roots, specifically from oilseed radish, have reached the tile lines and were blamed for plugged tile. Roots plugging tile lines is not a new phenomenon so farmers should not jump to the conclusion on the cause. Other factors may contribute to tile plugging, such as improperly installed tile with low spots where sediment and water can accumulate, thus attracting roots. What can be done if tile plugging is a concern? Plan to manage cover crop growth. Consider planting the cover crop in mid to late August and schedule more intense grazing in fields where tile plugging may be a concern. Change the seed mix to include more shallow rooted species or winterkill cover crops. Tile plugging from cover crops is very rare. A warm late fall gives cover crops a long window for growth and increase the chances for roots to grow deep into the soil profile.”
Following soil test recommendations is always advised–these cover crops are expected to provide enough growth to feed livestock. Usually manure or 50 to 60 pounds of N/acre is a minimum requirement. The non-legume plants really respond to nitrogen.
Be aware of livestock health risks that are dependent on the plant species used. Bloat, nitrate toxicity and others are a possibility, especially if hungry animal overeat on a new pasture. To reduce risk, make sure livestock have a full stomach before turning them onto a new type of pasture and provide access to hay. Including oats and other grasses with brassicas and legumes also reduces the risk of bloat. When these precautions are followed the risks are low.
Any time fields are grazed while wet, soil compaction can be a result, especially on heavier ground. Late fall and early winter grazing is often done in wet soil conditions, and some compaction will result. The best site locations are on lighter, well-drained soils. But research studies have shown that if management pulls the grazing animals out during times of excess moisture, the benefits of fall grazing will out-weigh the compaction issue. Soil fertility and crop yields often improve after cover crop grazing.
Here is some insight on the plant species to consider for cool season mixes seeded in late summer for grazing after November 1 in Michigan.
Seed 6 to 12 pounds in mixes. Oats are great for fall grazing, will stay green into December and will die out in January. Oats may start producing seed 45 – 65 days after planting, which may be a concern if producing grass fed beef.
Wheat, Rye or Triticale:
Seed 6 to 12 pounds per acre in mixes. Wheat, rye, or triticale will have less fall growth than oats but will survive the winter and provide substantial spring growth. Be aware of crop insurance spring-time termination guidelines for cover crops to be eligible for insurance on the following year’s cash crop.
Seed 6 to 10 pounds per acre in mixes. Annual ryegrass is short-lived (one to two years depending upon variety), highly nutritious grass that establishes fast in the fall and will survive most winters providing more growth in spring. Annual ryegrass can become a serious weed in fields rotated to grains the next year if proper herbicide timing is not followed.
Seed 2 to 3 pounds per acre in mixes. Turnip need 60 to 90 days to mature. Leaves, stem and bulb are highly nutritious. Turnip hold their feed quality well after a killing frost and are cold tolerant to 20 degrees Fahrenheit but eventually will winterkill. Some will just produce an edible leaf and stem but no tuber. Some will re-grow after grazing.
Seed 2 to 4 pounds per acre in mixes. Rapeseed needs 45 to 100 days to mature. Most can be re-grazed. It produces a highly nutritious, edible leaf and stem but no tuber. Some are cold tolerant to -5 F.
Seed 1 to 2 pounds per acre in mixes. Radish needs 70 to 85 days to mature. It has vigorous fall growth of highly nutritious leaf and tuber that livestock like and do well on. Radish holds nutrient value well after killing frost. Taproot hairs can penetrate compacted soil hardpans and mine nutrients from the subsoil.
Seed 2 to 4 pounds per acre in mixes. Red clover will provide some fall growth but will be more productive the next spring for spring grazing. It can last for 2 to 3 years, so if rotation crops are planned the next summer, termination options should be factored in. When given the chance to mature, it will produce residual soil nitrogen that can benefit future nitrogen-loving crops.