With significantly higher than normal precipitation in eastern South Dakota, many producers will soon be seeking a Plan B for their flooded-out row crops. Annual forages often work well within the crop insurance system. 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 different production environments and goals, soil types, and management techniques.
Management Considerations
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.
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, see the University of Wisconsin’s Herbicide Rotation Restrictions in Forage and Cover Cropping Systems publication.
Insurance and Farm Service Agency Guidelines
Be sure to check with your insurance agent and FSA representative on all details regarding the seeding of your cover crop or forage crop. Although forages are typically allowed in “prevent plant” situations, your flood insurance may not operate the same way. Frequently asked questions and answers regarding insurance can be found on the Risk Management Agency website.
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 SD Cover Crop Poster lists common South Dakota cover crops and their purpose ratings, seeding rates, and seeding depths.
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 2025 in mind before planting. It is generally recommended to plant cover crops with various growth habits that are complementary to the subsequent cash crops. For example, consider planting primarily 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, and triticale. Some species, such as vetch and Italian ryegrass, can stay dormant for a prolonged period (hard seed) and germinate the following spring. This doesn't eliminate these crops as an option; it simply requires prompt spring attention and management, as these species may be valuable to utilize excess moisture in a potentially wet spring.
Weed Control
When planting a 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, radish, or turnips) can also aid in weed suppression.
Soil Fertility
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 check current soil test levels. In many situations, low nitrogen application rates (30 to 60 lbs./a) will provide considerable growth for cover crops (especially grasses); it is also important to apply the appropriate rate of nitrogen when planting for forage purposes to limit the level of possible plant tissue nitrate-N accumulation should plants experience drought or other stresses. 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. 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 rather than most warm-season crops. 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.
Silage/Forage Considerations
If corn silage is not an option, and possible replanting could occur soon, consider a couple close alternatives, such as forage sorghum, or sorghum-sudangrass. In some studies, forage sorghum was ~85% the feed value of corn silage. Additional grain could be included in diets to meet performance objectives compared to feeding corn silage. Sorghum-sudangrass with the Brown Mid Rib trait may be slightly lower in energy content, but produces fiber digestibility similar to corn silage. Although forage sorghum can be an excellent feed alternative to corn, it generally has a short cutting window at mid-to-hard dough, and it can be difficult to harvest at the proper moisture (62 to 72%), especially if the crop is direct cut (not wilted prior to chopping). In some cases, non-heading types will require a killing frost to get plants dry enough for ensiling, which causes quality losses. If forage sorghum is too wet at harvest, corn grain or other forage dry matter can be added to the pile or bunker. Keep in mind that prussic acid poisoning can be a problem with either of these grasses. It’s found in highest concentrations in the leaves and new shoots following a freeze, making cattle susceptible to poisoning. For more information regarding feeding sorghum or sudangrass forages see this ISU Extension resource.
The Bottom Line
Although there are many factors to take into consideration, annual forages and cover crops can be an excellent tool to mitigate the challenging planting season. Cover crops not only reduce fallow acres, but also enhance soil health and provide supplemental forage. For more information, please do not hesitate to contact your nearest SDSU Regional Extension location or local NRCS office for cover crop/forage crop recommendations and other assistance.
