Start by assessing the stand. If 75% or more of its production still comes from desirable species and the plant counts are reasonable, improve its management and fertility, or seed into the existing stand. Less than 50% from desirable species points to poor production, and that's when breaking and reseeding is worth weighing, against its cost and the time the field is out of production.
Assess First
The Alberta Forage Manual sets out what to look at:
- Plant counts: 6–10 plants per square foot (65–110 per square metre) of bunch-type grasses and legumes should be enough for reasonable production.
- Alfalfa stems: in a pure alfalfa stand, 45–55 stems per square foot (485–590 per square metre) gives maximum yield.
- Species mix: good stands get 75% or more of their production from desirable species; under 50% points to poor production.
- Soil test: sample the areas showing poor growth or weed invasion separately, to find nutrient problems.
Then find the underlying problem and fix it, whether grazing management or soil fertility: an invasion of undesirable species can be a symptom of either. Fixing it cuts the need to rejuvenate the field again.
Option 1: Fix Management and Fertility
Rejuvenating without removing the stand keeps the field producing and avoids the cost of breaking it. Fertilizer is the method where the soil is short of a nutrient, and it helps a "sod-bound" stand, where production is low though plant numbers are high, most often in creeping-rooted grasses such as smooth bromegrass. Herbicides can suppress weeds, but the benefit won't last unless grazing or fertility changes too, and most herbicides that control broadleaf weeds also suppress or kill legumes.
Option 2: Seed Into the Stand
Seeding into the existing stand can thicken it, but new seedlings establish more slowly than in a conventional seeding, and success depends heavily on the weather, especially rain while they establish. It works better in bunch-type stands, such as alfalfa or orchardgrass, than in an old stand of smooth bromegrass or creeping red fescue, and the old top growth should be grazed or cut off first. To thicken a poor alfalfa stand, seed into it while the stand is still young: established alfalfa releases toxins into the soil that hinder new alfalfa.
For the seeding, Great Plains makes no-till drills such as the 1206NT, which can seed up to three different seeds at three different rates at the same time. GPK can supply most Great Plains and Kverneland equipment for this work.
Option 3: Break and Reseed
Breaking the stand and reseeding gives you a fresh start with new species, but it's costly, it interrupts your supply of pasture and hay, and it raises the risk of soil erosion, surface runoff and a loss of organic matter. You may need to reduce livestock numbers or find other pasture or stored feed while the field is out of production.
To remove the old stand, the manual finds conventional tillage generally less effective than spraying it out with a non-selective herbicide, which also lets you seed straight into it without tillage. Spraying in late summer or early fall gives better control than spraying in spring, and leaves a better seedbed for seeding the next spring.
Common Questions
Can I just fertilize?
If the stand still has good species and density, fertility and management may be all it needs. A soil test will tell you.
Can I reseed alfalfa straight after alfalfa?
No. The manual says to leave at least one growing season between the time all the alfalfa plants have died and reseeding alfalfa.
Which species should I seed?
See our posts on the best grasses and legumes for hay and for pasture in the Peace Region.
Sources: Alberta Agriculture's Alberta Forage Manual (2nd edition, 2009), Pasture and Hay Rejuvenation; Great Plains' 2024 Product Guide.
