People who drive past Thompson Farms, near Osage City, KS, may do a double take at the soybean-streaked wheat fields.

Like many producers, the Thompsons (brothers Doug and Keith, and Keith's son, Ben) have tried — with checkered success — to get a head start on the season by planting soybeans in growing wheat.

But few are more persistent at relay cropping. After trying several planting dates and methods, the Thompsons have developed an interseeding technique that succeeds with both wheat and beans.

“Relay cropping is a timing tap dance,” says Keith Thompson. “You need to plant beans early, before wheat begins to joint. But soybeans planted this early are subject to late frosts, and grow too tall and leggy by the time wheat is ready to harvest. The beans will grow above the wheat by harvest, so the combine clips soybean plants below the growing points.”

The Thompsons found a solution last year, with help from Lan-dec Ag, Monticello, IN, and Claude Butt, its senior agronomist. Landec Ag supplies soybean seed that is coated with a phase-change polymer called Intellicoat. Intellicoat, in effect, forms a timed-release capsule around the seed that delays germination by about two weeks.

“Last year, we planted coated Group IV soybean seed on April 5,” recalls Keith Thompson. “They came up in 12 days. That's about the same time our main-crop soybeans would be germinating.”

The Thompsons made another change in their relay-cropping strategy.

“Our wheat drill is on 7.5” spacing,” says Keith Thompson. “We plug every fourth drill hole to leave a blank row every 30”. Then, we come in and plant beans with a 30” planter in those blanks. We use a six-row planter that meshes exactly with our 15' drill. This way we don't have to buy any new equipment.”

That blank row gives soybean plants more room and sunlight so they branch out more than when planted directly in drilled wheat. At the same time, the wheat in rows on either side tiller more. Yields are reduced by only 10-15%, compared with solid-seeded wheat.

“When we combined wheat, the sickle was clipping only a few top soybean leaves; nothing below the growing point,” says Keith Thompson. “Our wheat made more than 40 bu/acre, and relay-planted beans yielded nearly 30 bu. And last year wasn't an ideal season for either wheat or beans.”

Butt's strategy was similar in 26 relay-planting trials in Ohio and Indiana. “We plant wheat and interseed soybeans both in 15” rows. Wheat is sensitive to its growing environment and it tillers more in 15” rows than in narrower rows,” he says. “In our trials, wheat (soft red winter) averaged 65 bu/acre and relay-planted beans made more than 25 bu. In fact, we believe this system can take doublecropping 100 miles north.”

There are some potential drawbacks with the system, however.

“Planting polymer-coated seed adds another $10/acre to costs,” says Ben Thompson. “Also, where we leave a skipped drill row, weeds sometimes sprout in that track and can get pretty tall by the time wheat is combined.”

Still, the technique beats any relay-planting scheme the Thompsons have tried before, for both wheat and beans.

“We'll go the same way in 2003,” says Keith Thompson.

Landec Ag offers a packet of information on relay cropping. Contact Claude Butt at Landec Ag, P.O. Box 898, Monticello, IN 47960. Phone: 800-241-7252.