What's Up at the USDA Office?
Deadlines/Dates
August 2: Primary Nesting Season Ends
August 12: Deadline to submit an SDRP application
Grazing Cover Crops: A Practical Tool for Feed, Soil Health, and Nutrient Cycling
Cover crops are already a valuable tool for protecting soil, reducing erosion, and improving water quality. When managed well, grazing those cover crops with cattle, sheep, or other livestock can add another layer of benefit, turning a conservation practice into a source of feed and farm flexibility. When planned correctly, cover crops can provide fall or early spring forage, reduce stored feed needs, protect highly erodible soils, and recycle nutrients back into the field.
Small grains such as cereal rye, oats, triticale, barley, and wheat are among the most common cover crops used for grazing in northeast Iowa. Cereal rye is especially winter-hardy and can provide early spring growth before corn or soybean planting. Oats grow quickly in the fall but usually winterkill, making them a good option ahead of early spring fieldwork. Brassicas such as turnips, radishes, rapeseed, and kale can provide highly digestible forage, while legumes such as crimson clover, red clover, or winter peas may add protein and, in some cases, nitrogen credits.
Seeding date is one of the biggest factors affecting forage production. In northeast Iowa, cover crops intended for fall grazing generally perform best when seeded as early as possible after silage harvest, small grain harvest, or early soybean harvest. Aerial seeding into standing corn or soybeans can add growing days but depends on rainfall and canopy opening. Drilling typically gives the most consistent stand. For spring grazing, cereal rye seeded after corn silage or soybeans is often a reliable choice.
Producers should match grazing plans to forage supply. Generally, cattle should not be allowed to graze cover crops too short. Leaving at least 3 to 4 inches of residual growth helps protect the soil surface, maintain root function, and reduce erosion risk. On sloping ground, maintaining residue cover is especially important. Avoid grazing when soils are saturated, as hoof traffic can cause compaction, pugging, and reduced infiltration.
Strip grazing or rotational grazing is usually more efficient than continuous access to the entire field. Temporary electric fence can be used to allocate one to three days of forage at a time. This improves utilization, reduces trampling losses, and gives producers better control over residue height. Portable water systems or access to existing water sources should be planned before turnout.
Nutritionally, many cover crops can test very high in crude protein and energy, especially lush cereal rye or brassica growth. Because feed quality can vary widely by species, maturity, weather, and fertility, forage testing is recommended. Livestock should be introduced gradually to lush cover crops, particularly brassicas or rapidly growing small grains, to reduce the risk of digestive upset.
Producers should also be aware of possible nitrate accumulation, especially following drought stress, heavy nitrogen application, manure application, or frost events. Testing for nitrates is a low-cost risk management step.
Cover crop grazing also supports nutrient cycling. A significant portion of consumed nutrients is returned to the field through manure and urine. While distribution may not be perfectly uniform, managed grazing can help return nitrogen, phosphorus, potassium, and organic matter to the soil. Over time, living roots and residue can contribute to improved soil structure, increased biological activity, better water infiltration, and reduced runoff.
Before grazing, producers should review herbicide labels from the previous cash crop. Some herbicides have plant-back or grazing restrictions that may limit which cover crop species can be planted or when livestock can graze.
Grazing cover crops is not a one-size-fits-all practice, but it can fit many crop-livestock systems. Success depends on early planning, selecting the right species mix, managing livestock access, protecting soil conditions, and testing forage when needed. For Allamakee County producers, cover crop grazing can help stretch feed supplies while keeping conservation goals front and center.
Feel free to come into the USDA office with any questions about cover crops and grazing opportunities.
William Kopp
Yellow River Watershed Project coordinator
William.Kopp@USDA.gov
Yellowriverwatershed@gmail.com
(563) 568-2246 ext 3
Allamakee Soil & Water Conservation District
770 11th Ave SW
Waukon, IA 52172
