Prevented Planting and Crop Cover Considerations
By Stephen K. Barnhart, Department of Agronomy
There continue to be questions about cover crops and prevented planting options. With the ‘no grazing or harvest until after Nov. 1‘ qualifier, here are my initial thoughts.
‘Spring cereals’ – oats, spring triticale, barley, spring wheat
If planted in June, they will mature and likely shatter seed by mid to late summer. Shatter seed may produce some volunteer plants in the fall. If the ‘rules’ permit mid-season management, then disking the mature cereals in late summer would effectively ‘plant them’ for significant fall growth and retain erosion protection.
If planted in late summer, they would provide decent fall growth, but are subject to frost kill.
‘Winter cereals’ – rye, winter triticale, winter wheat
Brian Lang, an ISU Extension and Outreach field agronomist in northeast Iowa, planted rye in spring 2012. He clipped some and left some unclipped. The unclipped overwintered with noticeable winterkill. The ‘late summer clipped’ overwintered very well. Winter triticale would probably behave similarly; winter wheat would be more susceptible to winterkill. If planted in June, all would provide some forage after Nov. 1.
If planted in late summer, these crops should overwinter OK, but would not produce lots of fall harvestable growth. They would provide some grazing. If planted early to mid August, they would produce more fall forage.
Ryegrass planted in June would probably be OK; there should be some forage for grazing in November, maybe enough for mechanical harvest.
I wouldn't recommend planting perennial forage grasses and legumes (including clover) in June for future hay fields unless there is good season-long vegetation/competition control to keep light availability to the establishing forage seedlings.
Perennial forage grasses and legumes (including clover) for future hay fields could be planted in early to mid August. This might be considered a better planting time if there is adequate soil moisture and likelihood of average or better rainfall.
Annual forage legumes, such as crimson clover, Berseem clover and field peas or cowpeas, may not provide enough useable growth (or die prematurely) before Nov. 1 to justify their cost. Most of these also require a special rhizobia inoculant for adequate nodulation and nitrogen fixation.
Annual, warm-season, forage species (such as Sudangrass, sorghum x Sudangrass hybrids, millets and teff) are all frost/freeze sensitive and will likely winterkill and deteriorate by Nov. 1. They will provide cover and ‘scavenge’ or hold existing soil nutrients, but will not likely provide highly desirable forage by Nov.1.
Buckwheat will provide summer cover and ‘scavenge’ or hold existing soil nutrients.
Brassicas (turnips, kale, forage rape, ‘radishes’) should be planted from late July into August for best forage yield and quality by Nov. 1. If planted in June, most of these will likely ‘bolt’ and produce seed by fall. They can be planted with a cereal grain such as oats, triticale or rye. They are not legumes, but will intercept and hold soil nutrients like grasses. The brassicas will winterkill; however, depending on the cereal grain used, the cereals may regrow the following spring.
In addition to the economic decisions about cost and return alternatives to late planting, prevented planting, failed planting, insurance payments, etc., you also should consider the following:
- How the field is managed through the summer – weed management, erosion protection, etc.
- Whether you want the cover to winterkill or persist into the next growing season
- Seed availability
- Pre-applied nitrogen
- Susceptibility of these alternative cover or forage crops to carry-over herbicides
- Forage quality after Nov. 1; whether it will be grazed or whether there will be a stored forage option ( silage, hay).
Stephen K. Barnhart is a professor of agronomy with extension, teaching, and research responsibilities in forage production and management. Barnhart can be contacted at (515) 294-7835 or by email firstname.lastname@example.org.
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