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Cover Crops for Prevent Planting (07/04/19)

In eastern North Dakota, most farmers have at least one field that will qualify for compensation under the USDA-RMA Prevented Planting Program.

In eastern North Dakota, most farmers have at least one field that will qualify for compensation under the USDA-RMA Prevented Planting Program. The week of June 17, Dr. Wick at NDSU organized a series of Prevent Plant (PP) Café Talk meetings in the southeast quarter of North Dakota, in cooperation with the ND Corn Council, ND Soybean Council and ND Wheat Commission, and what follows are highlights from the discussion.

Cover crop seeding into PP is not mandated by the program, but it is encouraged by NDSU scientists because past history in North Dakota indicates that farmers that have a cover crop planted on their PP acres are much less likely to repeat their PP application for those fields the following year. Without something using up water in the PP fields, there is a strong possibility that PP would be repeated if precipitation next spring is close to normal.

Until recently, the RMA rules were that cover crop could not be grazed or cut for silage until November 1, which was OK if you farmed in Kentucky, but did not help ND farmers out, since sometimes that date is the start of winter. Last week, the rule changed to September 1, which means that ND farmers can hay or graze PP acres in cover crops after September 1. The cover crop species is not regulated, so anything can be seeded at any seeding rate; no rule on that either. However, it cannot be harvested for grain.

Planting cover crops not only serve as ‘biological tile drainage’, but they also serve to suppress weeds, which are already difficult to control depending on the species.

Cover crops to consider-

Rye- Cereal rye is the go-to for a grass cover crop that can over-winter. However, if the field can be seeded in the beginning of July, the rye seeding should be delayed until late July or early August to increase its over-wintering chances. Planting it too early has been shown to decrease winter hardiness. Also, if corn is the crop for 2020, the rye should be terminated a couple weeks before corn planting to avoid yield depression. Soybean is very tolerant to rye and can be planted into the rye ‘green’. Termination then depends on soil moisture. If the spring is dry, terminate the rye earlier.

Annual ryegrass- NDSU Extension does not recommend this grass, because it can easily become a weed in subsequent crops.

Sorghum-sudan alone or in a mix- Sorghum-sudan uses a lot of water and produces a lot of biomass in the heat of the year. Its use is particularly useful if the field will be grazed, or cut for silage (not hay). In a mix, the rate of seeding is 2 lb/acre. Any more than 2 lb/acre, the sorghum-sudan will take over the field, because it is a strong competitor. If planting alone, the rate is 10 lb/acre.

Oats- Oats are almost as tolerant to salts as barley. Since it is a short season crop, its planting should be delayed until about August 1. Oats can also be used as a ‘relay’ cover crop to provide cover and water use early, then it can be terminated and rye or something else can be seeded to complete the growing. If planted earlier than August 1 it will likely be at haying stage before September 1. Haying later will reduce the quality of the hay. This recommendation is also for forage barley.

Barley- barley is our most salt tolerant crop. Since it matures quickly, waiting to seed until August 1 would be wise, planting a relay crop before, or growing weeds and controlling their seed production with mowing, terminating them before the barley is seeded.

Spring wheat- Spring wheat can also be used as a cover crop, but it is not quite as salt tolerant as oats and barley. Seeding should be delayed until the beginning of August.

Millets- millets are good water-users and grow well in hot conditions and can be used both for haying and grazing. German millet seed is in shortage.

Winter Camelina- camelina is an extremely small-seeded broadleaf that overwinters. Plants usually do not survive the winter if planted earlier than the last week of August. It does not use a lot of water in the fall, but it uses quite a bit the following spring. If weed pressure will allow, seeding it with a grassy companion crop such as barley or oats would be best.

Field pea, faba bean, Austrian winter pea- These cover crops are legumes that work well in mixes. Field pea has the habit of bending over near maturity, so heavy stands will be difficult to seed into the following spring, so seeding rates should be low. Faba bean is an upright-growing plant, and turns black after freezing, lending itself to easy planting the following spring. Austrian winter pea has shown good winter survival (>50%) in Wyoming, Bozeman, MT, and Idaho, but not in North Dakota. Be sure to get the most benefit out of a legume by inoculating.

Sunflower, soybean- sunflower is not as salt tolerant as many think,, but adding it to a mix will increase deep water use if it is planted in July or early August. Seeding rates should be low, 1 lb per acre or less. Soybean is one of our least salt-tolerant crops, so its use if the EC is > 2 would be a waste. Its use in a mix would be its best use in fields with low salt content. Also, soybean or other SCN -host crop shouldn’t be used if you suspect you have soybean cyst nematode (SCN) in your field. Clovers- clover seed is expensive, and most clovers planted this late in the season will have little growth by freeze-up. Some growers might think that their contribution of N due to nodulation would be worth the risk, but they need to consider that any legume will use soil N before they ‘pay’ the nodulating bacteria to make their own.

Weed control in cover crops-

Herbicides are available to control weeds in pure grass stands, and pure broadleaf stands. However, if the cover crop mix contains both, then the grower needs to choose which would be best to leave alive. Group 4 herbicides like 2,4-D or dicamba will work well in grass cover crops, while Group 1 herbicides like clethodim will work well in broadleaf crops. In historically weedy fields, weed control should probably be prioritized over other agronomic factors.

If one chooses not to use cover crops, then mowing and tillage also are viable options for weed control. Please be aware that if tillage is used, there is a great deal of time before seeding in 2020. If the soil dries and the wind blows, much topsoil can be lost, and, often, there is not much topsoil left to lose. We would not recommend spending money on residual herbicides because weeds will eventually emerge in the absence of a crop canopy. Repeated applications of non-selective herbicides like glyphosate, glufosinate, and paraquat can be used in the bare ground situations.

The insurance representative-

It is most important that whatever is done, and whenever anything is seeded, communicate with your insurance provider to make sure they understand what you intend to do. Insurance agents are backed up in visiting fields, but a phone call can usually result in the ability to charge ahead with a plan. Asking forgiveness is the worst option.


Dave Franzen

Extension Soil Specialist



Abbey Wick

Extension Soil Health Specialist


 Marisol Berti

NDSU Plant Sciences

Forages and Cover Crops Researcher


Joe Ikley              

Extension Weed Specialist

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