It's been done before, with mixed success, as farmers try to give second-crop soybeans a head start by interplanting them into growing wheat.

But few growers have been more systematic - or more stubborn - about it than Doug and Keith Thompson. The Thompson brothers, along with their father, Jim, and Keith's son, Ben, are fine-tuning relay planting on their farm near Osage City, KS.

They plan to produce six crops in four years on as many of their 2,600 moisture-short acres as they can, with a goal of $300-400 gross per acre.

Along with double-cropped beans, the Thompsons also grow sunflowers and grain sorghum after wheat. In 1998, they even planted a short-season corn hybrid when wheat came off and got a passable crop.

"We're trying a lot of things," says Keith. "Farming is more fun with the Freedom to Farm act. We've heard the sad stories about relay-cropping beans into wheat, but we're convinced we can make it work here."

Making it work, though, involves walking a timing tightrope, adds Doug.

"We want to get soybeans drilled into wheat before the wheat begins jointing," he says. "That means planting beans in early April most years. If the wheat is at the joint stage, you damage a lot of it with the bean drill. To compensate, we hike the wheat seeding rate by about 10%."

It worked beautifully in 1996. Wheat averaged nearly 50 bu per acre, and the interplanted beans made 26 bu/acre.

"That was as good or better than any soybeans planted after wheat in this area," Doug observes, "although we had trouble controlling weeds in the soybeans after wheat harvest."

The next year - 1997 - the Thompsons went to a Roundup Ready soybean variety in about 100 acres of wheat. However, the weather double-crossed them.

"We had a warm spell right after we drilled beans in the wheat," recalls Doug. "The soybeans germinated, then were clipped by a late frost. About all we got out of our 1997 relay-planted beans was experience."

But experience can be a good teacher. For 1998, the Thompsons made some changes.

"We cut back the acres of relay-planted beans quite a bit," Doug reports. "We stayed with Roundup Ready soybeans; that lets us clean up weeds after wheat harvest. But we drilled the soybeans across wheat rows, rather than parallel to them. We damage less wheat this way."

They again drilled soybeans in early April, and the weather cooperated. In fact, at wheat harvest, the soybeans were so tall the combine sicklebar pruned two or three leaves off bean plants.

"We are trying a special seed coating that may cure both problems of having soybeans germinate too soon, and getting them too tall by the time wheat is ready to combine," says Keith. "It's a phase-change polymer coating that reacts to temperature and moisture. We only had a few pounds of bean seed with the coating last year - not enough to compare yields - but the coated beans germinated a week later than uncoated seed."

Wheat yielded 65 bu/acre in 1998. The relay-planted beans produced from 20 bu/acre to more than 35 bu/acre.

This spring, the Thompsons will give the "timed-release" coating a more thorough test, with three or four bags of seed.

"And where we plan to interseed soybeans, we'll plant wheat in 15" rows, with a split-bar planter," Keith adds. "I don't think we'll lose much wheat by planting in wider rows - maybe 10 or 12%. But this will give soybeans more room to branch out. Beans interseeded with wheat in 7" rows get pretty tall and spindly by wheat harvest."

So the Thompsons will add coated seed and wider wheat rows to their bag of relay-planting tricks. Other tricks include:

* Choosing full-season soybean varieties. They plant late Group IV beans into wheat and as their main-crop soybeans.

* Planting Roundup Ready soybeans. That lets them take care of weeds that shoot up after the wheat canopy is gone.

* Boosting seeding rates of both wheat and soybeans on interplanted acres. They drill for 900,000 to 1 million wheat plants per acre and 180,000 or more soybean plants per acre.

"Wheat is not a top profit-maker in this region," says Doug. "But it fits with what we try to do. By doubling crops behind wheat, we can earn a decent return per acre.

"I'm convinced the best way to grow a following soybean crop is to plant it in growing wheat," he adds. "We've learned a lot about relay cropping the past three years - including the things that don't work."