Annual forages or summer and/or fall cover crops can be a helpful forage alternative in drought situations. There is no ‘hard and fast’ blanketed mix or species that can be recommended to all producers, as each grower is in a unique circumstance with a different production environment and goals, soil types and management techniques unique to their operation. Rather than seeking the ‘go-to’ crop or mix of your neighbor’s choosing, ask yourself a few fundamental questions before planting an alternative option.
Factors to Consider
Herbicide History
Before planting an alternative to your intended crop, consider your crop rotation, as well as haying/chopping and grazing restrictions of herbicides previously applied; this includes herbicides applied in the previous growing season. For more considerations regarding herbicide carry-over, view the resource, Herbicide Rotation Restrictions in Forage and Cover Cropping Systems, courtesy of University of Wisconsin Extension.
Purpose
Always begin with the end in mind. Livestock feed, soil health, weed suppression, nutrient capture, soil moisture management, additional harvested forage, and grazing may all be common reasons to plant a cover crop. Try focusing on your own objectives when creating a planting plan. The U.S. Department of Agriculture Natural Resources Conservation Service’s South Dakota Cover Crop Table lists common South Dakota cover crops and their purpose ratings, seeding rates and seeding depths. The Midwest Cover Crop Council also offers a Cover Crop Selector tool that can assist in choosing a cover crop mix in South Dakota and surrounding states based on grower goals and management practices.
Insurance and FSA Guidelines
Be sure to check with your insurance agent and Farm Service Agency representative on all details regarding the seeding of your cover crop or forage crop, especially following an insurance claim on your cash crop. Frequently asked questions and answers regarding insurance can be found on the Risk Management Agency website.
Seed Availability and Price
Each year, demand for annual forage/cover crop seed varies, and some species may have risen in price due to demand. This is important to take into consideration before choosing a species or mix to plant. Although most producers want to keep costs low, do remember that forage crops and/or improved soil health comes at a price, and some investment will be necessary.
Crop Rotation
Keep your previous crop and intended crop for 2024 in mind; it is generally recommended to plant cover crops of diverse growth habits that are complementary to the subsequent cash crops, for example, broadleaves prior to grass cash crops and vice versa.
Termination
Many cover crops will winter kill or die after a late chopping. However, some species may survive the winter, such as cereal rye, winter wheat, triticale, and others. Some species, like vetch and Italian ryegrass, can stay dormant for a prolonged period (hard seed) and germinate the following spring. This does not eliminate these crops as an option; it simply requires prompt spring attention and management, as these species may use valuable spring moisture intended for a cash crop. Conversely, they are helpful in taking up moisture during a wet spring.
Weed Control
When planting a diverse cover crop mix, it can be nearly impossible to chemically control weeds during the growth of the cover crop. If a mix is well planned and raised under ideal growing conditions, the cover crops can usually out-compete weeds. However, if particular weeds are a concern, control issues should be considered before selecting cover crops. A thorough burndown before planting also helps with weed suppression. Cereal/winter rye is known for its inherent allelopathic characteristics, or its ability to suppress weeds by the production of biological chemical substrates that are harmful to other surrounding species. Other cool-season grasses and sprawling, or more ground covering, broadleaf crops (such as vetches, or radish and turnip) can also aid in weed suppression.
Soil Fertility
Generally speaking, if a producer is intending to use cover crops as forage, applying lower rates of nitrogen at planting can be cost-effective in the end. Consider previous crop credits if legumes were planted and current soil test levels. In many situations, low nitrogen application rates (30 to 60 pounds per acre) will provide considerable growth for cover crops (especially grasses). In drought situations, it is important to consider whether nitrogen fertilizing combined with dry conditions could cause high nitrate build-up in the plant. Therefore, if planting a forage crop after harvesting a cash crop that was salvaged for feed, no nitrogen fertilizer may be recommended. Knowing your soil test levels and monitoring the field as plants progress is a best practice in determining whether additional fertilizer may be needed. Check the South Dakota Fertilizer Recommendations Guide for suggested soil fertility guidelines for major South Dakota crops.
Planting Time
As most cover crops are grown in blends, it is difficult to establish an exact seeding date based on individual crop species. However, there are suggested planting windows for crop types based on the proportion of different cover crops species in the blend. Warm-season species (such as forage sorghums, sorghum-sudangrass, buckwheat, sunflower, teff grass, and others) should ideally be planted from late spring into early summer. After the third week of July, as average daily temperatures tend to decrease due to lower nighttime temperatures, cool-season species (such as small grains, peas, clovers, vetch, and brassicas) are recommended instead. When planted within these suggested guidelines, cover crops should have ample growth time for forage harvest near or after September 1. Due to growth habit, some species in the mix may mature faster, which should not inhibit forage harvest. When dealing with drought conditions, it is important to watch for a forecasted rain before planting, in hopes of getting your alternative forage crop started. With dry soils and no rain in the forecast, many producers choose to wait to invest in planting seed until the chance of moisture improves.
Choosing a Forage Species
Cool-season species that utilize less moisture than others and may handle moisture-stress well; options include forage barley, field peas, wheat, and forage oats. Drought-tolerate warm-season options include hay millets, (Siberian foxtail millet often outshines other millets in drought), sorghum, sudangrass, sorghum x sudangrass, or teff grass. Winter annuals can also provide options for growers looking forward to 2024; winter rye or winter triticale may provide grazing or hay in the spring if adequate moisture is present. This does not mean other forage species cannot be planted, but be aware the some cover crops require more moisture than others do.
In Summary
Although there are many factors to take into consideration, annual forages and cover crops can be an excellent tool to boost forage production, reduce fallow acres, and enhance soil health. For more information, please do not hesitate to contact your nearest SDSU Extension Regional Center or your local NRCS office for cover crop/forage crop recommendations and other assistance.
