By Jenny Rees
Late-season hail affected fields across Nebraska in 2018. Now that crop insurance adjusters have made decisions regarding many of these fields growers are asking for cover crop information for weed management, excess nitrogen uptake, and forage options.
Before Seeding a Cover Crop
Always be sure to check with your crop insurance agent before seeding a cover crop into hail-damaged fields. It’s also important to check replant, forage and grazing restrictions regarding the herbicide program you used and any delay necessary before seeding a cover crop and any forage restrictions to grazing a cover crop. (See Replant Options and Herbicide Rotation Restrictions and Forage, Feed, and Grazing Restrictions for Row Crop Herbicides, both excerpted from the 2018 Guide for Weed, Disease, and Insect Management in Nebraska, EC130.)
Figure 1. Severely hail-damaged corn field where the ears are the top-most part of the plant. Following severe hail damage, cover crops can offer a variety of benefits from using available nitrogen to aiding weed control.
Cover Crop Options
The following photos show three situations that we may be seeing now to varying degrees:
- corn crop with only ear and stalk remaining (Figure 1),
- seed corn field that may or may not be destroyed, depending on company determination (Figure 2), and
- soybean field where stems are dying and pods aren’t filling. It will most likely yield from 2-10 bu/ac if taken to harvest (Figure 3).
Figure 2. A seed corn field severely damaged by hail.
We’re hearing several concerns from growers. One is that weeds are emerging in these hail-damaged fields and they’d like to get a cover down to reduce light interception and help manage weeds. They’re also concerned that there’s nitrogen left in the soil that went unused by damaged crops or that has been scavenged by the soybeans. A cover crop can utilize that nitrogen and keep it in upper soil layers instead of allowing it to leach. Some growers are also thinking about the forage value available from soybean that won’t be harvested or the cover crop planted.
In general, we’re at an interesting time for making cover crop decisions. Typically we use September 1 as the divider between planting small grains such as oats that will winterkill and winter hardy cereals such as rye or triticale (planted after September 1). Even with brassicas such as turnips, collards, or rapeseed, we’d recommend the cutoff for seeding to be within the next two weeks. Because of this time frame, mixes may be beneficial because they’ll take advantage of whatever weather we have for the rest of the season. Simple, inexpensive mixes may allow for at least something to become successfully established.
Figure 3. Severely hail-damaged soybean field where stems are dying and pods aren't filling.
Your cover crop seed supplier can help with cover crop options and seeding rates. The following are a few recommendations:
Table 1. Cover crop considerations for late-season hail-damaged crops
| COVER CROP | USE/GOAL | WHEN TO PLANT | HOW TO SEED | RATE
(PER ACRE) | ADDITIONAL NOTE |
|---|
| OATS | Weed Management | By Sept. 1 | Drill best. Can fly on. | 30-40 lbs | * |
|---|
| OATS/RYE MIX | Weed Management | By Sept. 1 | Drill best. Can fly on. | 30 lbs each | * |
|---|
| OATS | Forage | By Sept. 1 | Drill best. Can fly on. | 80-90 lbs | * |
|---|
| OAT/RYE MIX | Forage | By Sept. 1 | Drill best. Can fly on. | 30-40 lbs of rye and 50-60 lbs oats | * |
|---|
| BRASSICAS (TURNIP, COLLARD, RAPESEED)-NOT OILSEED RADISHES | Cover ground, forage, nitrogen uptake | By Sept. 1 | Fly on for quicker establishment. | 5-6 lbs | — |
|---|
| RYE | Weed management, cover ground, forage, nitrogen uptake | After Sept. 1 | Drill best. Can fly on. | 50-60 lbs | * |
|---|
| *If adding a brassica to any of these small grain options, only 2 lb/ac is needed. Rapeseed isn’t as well known, but is an inexpensive and good option for consideration. |
Other Forage Considerations
Conclusion
There are a variety of options to consider now depending on the grower’s specific field situation and goals. A cover crop can help remove excess nitrogen, cover the ground to aid in weed management, and provide a forage option. Regardless of the goal, timing matters now, and because of that, mixes may be a better option to ensure at least something gets established to meet the goals.