Roger Elliott says he harvested a whopping 81/2 tons/acre of alfalfa dry matter from a 25-acre field in 1997. And he's set on averaging 9 tons/acre from all of his 200 alfalfa acres.

If he reaches that goal, it'll be with help from precision farming.

Last summer, Elliott, a dairy farmer from Evansville, MN, built a yield monitoring system for haylage. This year he'll install a moisture tester on his forage harvester, then start gathering yield and soil fertility information that will let him farm all his alfalfa by the foot.

In fact, he plans to precision-farm his entire farm, grid-mapping fields and monitoring yields of corn silage and corn grain, too.

It looks like Elliott will be one of the first farmers to fully implement precision farming practices on alfalfa, and he's excited about the possibilities.

"I can go back to each variety throughout the life of the stand and pull weights on it," says Elliott. "I can see how it's doing on the high spots in the field and the low spots. Then the next step will be to find out why it's doing better or worse in those spots.

"Say I'm getting just moderate stands on the low spots," he continues. "Could I justify tiling it or not? Or if a high spot isn't doing quite as well as other spots, should I put on more fertilizer? Now I can put numbers to it; I don't have to guess anymore."

His first step toward precision farming was mounting load cells under his dump wagon and connecting them to a Rockwell International global positioning system (GPS) unit in his tractor cab. The unit gives weight readings twice every second.

That part was easy. Coming up with a software package to record data was much harder. Complicating the task was the fact that load cells sometimes give "ghost" readings when the wagon bounces. So Elliott needed software that would throw out readings that were too high or too low.

Developing workable software took most of the summer, but Elliott didn't tackle the problem alone. Del Glanzer, his crop consultant, and Larry Zillox, his county extension agent, helped.

"All three of us are learning together," says Elliott. "It's kind of a team approach." Rockwell engineers were a big help, too.

"They were fantastic to work with. They were out here riding in tractors with me, so I knew it was going to work."

The system was working by early fall. Just a little fine tuning will be needed this summer, says Elliott.

With help from another engineer, Elliott now is working on an on-the-go moisture tester. It's needed so yield data can be adjusted to account for moisture variations in the windrow and changes that take place during the day.

"We're trying to decide whether to put it in the spout or somewhere by the pickup, like between the compression rollers," he reports.

Before long, Elliott expects to change alfalfa seeding and fertilizer rates within fields. He might even seed more than one variety in the same field. For example, a phytophthora-resistant variety could be seeded in low spots and a non-resistant one on higher land.

With rolling land and several soil types in each field, Elliott's farm is well-suited to precision farming. He manages his alfalfa intensely, using heavy seeding rates (19 lbs/acre last year) and killing the companion crop with a herbicide when its erosion-prevention benefits are no longer needed.

The field that yielded 81/2 tons last summer had received heavy amounts of manure in recent years.

"It's been surprising to continually cut waist-high alfalfa out there," Elliott comments. "If I can do it on that field, why can't I do it on the rest of the fields?"

With precision farming, he hopes to do at least that well on all his fields. He might not improve yields on the best parts of fields, but will be able to give special attention to areas that aren't keeping pace.

"That's the whole benefit of GPS - you can keep finding that same spot, year after year," he says.