Managing Forage Stands Under Water
Impact of Flooding
Flooding reduces oxygen in the soil, which roots need for survival. Plant response varies by species, stand age, health, fertility, and flood duration.
- Alfalfa: Least tolerant
- Grasses: Most tolerant (e.g., reed canary grass)
- Clovers: Intermediate tolerance
Harvest delays are common due to slow spring growth and saturated soils.
Alfalfa
- Tolerance:
- Alfalfa: 1–2 weeks
- Alsike clover: 2–3 weeks
- Red clover: 3–4 weeks
- Assessment:
- Check when fields dry and alfalfa reaches 6 inches.
- Stem density guide:
- 55 stems/sq. ft = good yield
- 40–50 stems = moderate yield
- <40 stems = consider replacement
- Management:
- Severely damaged stands: cultivate and reseed if stand is less than 2 years old. Beware of autotoxicity of older stands.
- Partial damage: expect weed issues; limited herbicide options for dandelions.
- Reseeding:
- By mid-June with a companion crop (½ rate oats/barley).
- Harvest cover crop early as silage.
- Late summer seeding (August) possible without cover crop; allow 6 weeks growth before frost.
Grasses
- More flood-tolerant than alfalfa.
- Bromegrass: >3 weeks
- Meadow fescue, meadow foxtail, timothy: ≥6 weeks (dormant)
- If reseeding is needed, delay until August for proper seedbed preparation.
Annual Forage Options
For producers short on hay or pasture when perennial forage crops need to be reseeded:
- Greenfeed/Hay/Silage:
- Oats: 1.5–3 bu/ac (55–115 kg/ha)
- Barley: 2–3 bu/ac (106–160 kg/ha)
- Harvest at late milk–early dough stage (~8 weeks after planting).
- Pasture Mixes:
- 10 lb/ac (11 kg/ha) annual ryegrass +
- 1.5 bu/ac (53 kg/ha) oats or
- 0.3 bu/ac (20 kg/ha) fall rye
- Ready for grazing in 6–8 weeks; fall rye mix provides early spring pasture next year.