Alfalfa stands have a limited lifespan – usually three to five years. A lot of care and work is put into those stands. They age, and what to do with them is a concern. Converting alfalfa to grass and grazing pasture is a viable and economical way to revive an old alfalfa stand but farmers sometimes have a hard time parting with a good alfalfa even if yield is on the decline. And rightly so – it’s a hard decision to make.

As a general it’s usually best to quit while you’re ahead. Stand decline in alfalfa is inevitable. As an alfalfa stand ages stems become thicker and “leggy”, producing less green leafy material per square foot and fewer stems. Disease, winter injury, disease, stress, traffic from tractors, implements and wheel lines all take a toll.

Evaluate your Stand

Evaluate your stand in spring or early fall when plants are about 4-6 inches tall. You should have 3-4 plants per square foot or 25-30 stems in third-year alfalfa. Sample different areas of the field and average your results. In most alfalfa stands yield plateaus at about 45-50 stems per square foot.

Evaluating a pivot in Nevada. Great Basin Seed assisted the rancher in successfully converting 4 alfalfa pivots, including the one pictured, to pasture grasses for a calf operation.

Alfalfa Autotoxicity

It is tempting to simply plant new alfalfa seed into your stand to “thicken it up”. Resist the temptation and avoid this practice. Alfalfa plants release toxins into the soil as they grow and mature. It’s a phenomenon called alfalfa autotoxicity. New alfalfa seedlings do not carry the immunities necessary to survive in the toxic environment and will either never germinate or they germinate and quickly perish.

Combining Grasses and Alfalfa

The good news is that autotoxicity doesn’t affect the other forage species. Interseeding grasses into an old alfalfa stand is an excellent alternative to disking your alfalfa. You can convert it into a healthy, productive pasture. So what grasses are best to overseed into alfalfa? The following grasses are excellent choices for alfalfa interseeding:

Perennial Ryegrass
Tall Fescue
Meadow Brome
Annual Ryegrass
Intermediate Ryegrass

Interseeding Grasses or Mixes into Alfalfa

When converting alfalfa to grass and grazing pasture the time of interceding is important. Your new grass seedlings are competing for water, real estate and nutrients. Sow early enough that they have time to establish before the alfalfa becomes too competitive. No-till drilling is the most efficient and successful method of interseeding, but broadcast seeding will work. We recommend a light surface disturbance of some kind if the broadcast method is used. A spring tooth harrow works well. Where available, follow your broadcasting with a packer of some kind.

Winter or “dormant” seeding is a viable option for establishing pasture. Sown late winter/early spring (Feb/March) for best results. Winter or dormant seeding carries the risk of winter or frost kill, and results vary.

We recommend a seeding rate of:

15-20 lbs. per acre broadcast
13-15 lbs. per acre no-till drilled

Alfalfa Autotoxicity

Properly planned, executed and managed a grass/alfalfa pasture can add years of productivity. It can open grazing and rotation possibilities for your operation.

For help with your next project give us a call.

Converting Alfalfa to Grass and Grazing Pasture