A forage expert with Saskatchewan Agriculture says it is possible for producers to direct seed forages into terminated forage stands.
However, success depends on weed control, soil conditions and the ability to seed the new crop at the proper depth.
Michel Tremblay told forage producers at the Western Beef Development Centre’s field day in Lanigan, Sask., that they can save time and money by direct seeding into forage stubble.
Spraying and direct seeding is less expensive than tillage and reseeding and can produce good results under the right circumstances.
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However, producers should assess field conditions carefully before making a decision.
“Not all fields are candidates for direct seeding forages back onto forage stubble,” he said.
“It’s important that you take a critical look at what you’ve got out there in your fields.”
Tremblay said he has had mixed results.
Seeding depth is a critical consideration, which means ground that is rough, uneven or infested with pocket gophers will pose a problem.
Forages should be ideally seeded at a uniform depth of about one or two centimetres.
Planting deeper will reduce chances of emergence and establishment.
Producers with rough ground may be able to level their fields using a land roller or a levelling device that can be dragged across the surface.
However, direct seeding should probably be avoided if the land is too uneven.
Control of existing vegetation, including old forage plants, is another key issue.
“You’ve got to get rid of the existing and undesirable vegetation and try to start out with as clean a slate as possible.”
The most common weeds in forage stands are dandelions, quackgrass, Kentucky blue grass and foxtail.
Producers should pay special attention to those species, but they should also look for a good kill of existing forages.
“You’ve got to control your forage stand or remnant plants to eliminate the competition and make it possible for those new seedlings to establish in there,” said Tremblay.
Producers must be honest with themselves when assessing candidate fields, he added.
“Like my dad used to say, there’s never enough time and money to do (a job) right but there’s always enough money to do it twice.”
A tank mix of glyphosate and a Class 2 herbicide such as 2,4-D will probably provide adequate control if populations and densities of trouble weeds are reasonably low, although other tank mixes can also be used with good results. Producers don’t have to worry about getting 100 percent control, but the cleaner the field, the better the chances of establishing a new crop.
Studies conducted in north-central Saskatchewan tested the efficacy of glyphosate tank mixes on controlling alfalfa and dandelions.
Fields were sprayed in late May, mid-July and late in the growing season before freeze up.
The tests suggested that later application dates provide better vegetation control.
Producers should also budget for a second herbicide application the following spring.
“There’s no getting around that,” Tremblay said. “You’ve got to get out there and give it another kick in the spring.”
Autotoxicity can also affect new stand establishment.
Some plants, including alfalfa, produce phenolic compounds that inhibit the growth of other plants, including new alfalfa seedlings.
The above ground material, including leaves, is the most toxic in alfalfa.
Soil covered with a lot of new alfalfa litter is more prone to auto-toxicity, but Tremblay said warm, healthy soil with good organic matter and ample moisture will break down phenolic compounds more quickly.
Autotoxicity problems should diminish significantly in fields that are sprayed in the fall and seeded the following spring.
Tremblay said good forage seeding practices should always be used, but they are particularly important when direct seeding into forage stubble.
He recommended using good seed, inoculating and carefully checking the seeding depth.
Shank mounted openers behind each opener are recommended.
“It’s never a good idea to cut corners when you’re seeding a forage and certainly if you’re using the technique (direct seeding), I would double that emphasis,” he said.
