Field burning alternative lets grass plants breathe

John Schmitz/for the Capital Press Craig Pope, owner of Agriweld in Monmouth, Ore., built this grass seed crown sweeper with the help of OSU Extension grass seed specialist Tom Silberstein. The unit got its first tryout this fall.

Crown sweeper exposes soil to spring warmth, inhibits rhizome growth


For the Capital Press

A new piece of equipment on trial in the Silverton Hills of Oregon could well give grass seed growers there an economical alternative to field burning, while at the same time maintaining seed yields.

A cooperative effort between Oregon State University and Agriweld, the bright red implement is designed to clear straw from the tops of creeping red fescue plants -- or any grass plant for that matter -- after harvest.

"To me, farming is vegetation management," said OSU Extension grass seed specialist Tom Silberstein, who helped design the machine. In the case of fescue plants, he wants to encourage crown regeneration as well as discourage weeds and other undesired materials from growing between rows.

"Rather than (baling off) and chopping everything down, I'm just exposing an area I want to grow. If this works, it will be a really inexpensive way to do it."

If successful, the sweeper will give creeping red fescue plant crowns a better environment in which to regenerate next year's crop.

"By opening up it up, I get sun exposure down into the soil area, and this warms it up, and this helps (crowns) grow a little faster," Silberstein said.

Silberstein is also experimenting with row spraying, a practice common in south valley annual ryegrass seed fields.

As for clearing off and exposing plant crowns to the sun, "this has not been done before."

The crown sweeper features barbed discs that clean grass stubble off plant rows and move the debris to the side, piling it up between rows. One characteristic of creeping fine fescue plants is that they produce below-ground runners (rhizomes) that spread out and form new plants, thus the word "creeping." These new rhizomes will be held in check by the straw mulch heaped over them between rows.

One disadvantage of burning fescue fields year after year is that seed yields will eventually fall off due to plant congestion, a condition Silberstein wants to eliminate with the crown sweeper.

"The more plants you have, the more competition and the less energy they have to produce seed," he said.

"They don't produce seed heads. They just maintain a vegetative state."

Silberstein said that because of the shallow, rocky soil and steep hills in the Silverton Hills, it's difficult to use bulky flail mowers to chop straw after harvest. The practice can also be dangerous.

Silberstein is also working with an annual ryegrass seed grower in the south valley who is using a similar unit to clean rows off so that a new crop can be direct seeded.

Silberstein was planning on using the row sweeper for the first time towards the end of September. He won't know until harvest next summer what impact the machine had on yields.

The unit that Agriweld built cost around $8,000 and was paid for by grass seed research funds.

Should the prototype crown sweeper become a production item, the cost could drop by as much as a thousand dollars or more.

Freelance writer John Schmitz is based in Salem, Ore. E-mail:

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