Alfalfa yield monitor providing solid data for crop management

You bring that memory stick?” Corcoran, Calif., farmer Pete Rietkerk asked agronomist/consultant Jim Yager of Fresno, Calif.

Yager pulls a computer flash drive from his shirt pocket and hands it to Rietkerk, who plugs the portable data storage drive into the hay baler yield monitor.

It was as routine as Pete asking Jim to hand him a wrench to break loose a nut on a tool bar implement. Routine though it may have been, it is indicative of the growing utilization of computers, GPS technology, and precision agriculture devices in farming.

A decade ago, the flash drive interchange would have been as foreign as a team of mules cultivating a California cotton field. In a relatively short time, precision technology has taken agriculture into a remarkable new era, much like mechanization transformed the animal-powered era.

It started with satellite tractor guidance systems and has quickly evolved into aerial imagery, yield maps, and prescription agriculture — all with a simple goal in mind: keep farming profitable.

“Margins are so tight right now, with costs going up across the board, from fuel to fertilizers to seed, you have to be as efficient as you possibly can. Wasting any input is wasting money,” says Rietkerk.

Knowledge is imperative for efficiency, and the satellite/computer is making farming as precise as never before.

“You must have good data to make decisions,” says Rietkerk, which is one reason the third generation Kings County, Calif., grower has been the guinea pig for testing the first-ever alfalfa hay yield monitor to operate commercially in California.

He used it on four cuttings last season on about 750 acres of alfalfa and is using it again this year.

“You have to be patient working with precision ag technology. When you buy something that's supposed to work right out of the box, it usually doesn't. It takes a lot of time and phone calls to places like Australia and Canada to get this new technology to work” says Rietkerk, who farms 2,300 acres of alfalfa, cotton, grain, and pistachios.

“Jim and I had to do a lot of tweaking early-on to get information that was useful.”

“Some people who say a solution is just around the corner live in round houses,” laughs Yager.

Nevertheless, the Harvest Tec yield monitor is working well and providing good information. The device fits any large or small square baler, mapping fields on the go with a GPS satellite receiver. Rotating dual starwheels mounted on either side of the bale compression mechanism determine how much hay is needed to form a specified bale size. The wheels also read hay moisture content across the entire bale. One wheel is a positive sensor, the other negative.

“What you do is program into the GPS monitor the size and weight of the bale you're making, and the computer calculates yields as you bale the crop,” says Yager, who worked with Harvest Tec, based in Hudson, Wisc., in developing the monitor.

The data from the tractor-mounted monitor then can be downloaded into a computer.

“My first contact with Harvest Tec was at the Tulare farm show. They make equipment to add preservatives to hay, based on the moisture content of the bale. I realized that the moisture measuring capability was just a few steps away from a yield monitor.”

Yager has worked with Reitkerk for several years as an agronomist, and Rietkerk was a willing guinea pig to evaluate and validate the yield monitor.

Several things have proven useful about the system. The biggest is probably the moisture monitoring capabilities.

“Moisture content is very important in baling hay,” Reitkerk says. “You want to get it right for quality. Too dry, and leaves fall off; too wet and the hay barn can catch fire.”

Moistureis more critical in the large bales (his weigh about 800 pounds).

“When it gets too wet in a portion of the field, we can drive around the wet spots,” says Rietkerk, who also uses the moisture measuring capabilities to determine when to start bailing a field.

He makes the first three cuttings for dairy quality hay on a 28-day schedule. For summer hay, he stretches it longer for increased tonnage.

“One of the things we have learned is that the weaker, sandier parts of the field actually produce better hay,” says Yager, explaining that lighter soils are slower to re-grow than heavier soils. Therefore, when cut and baled, that hay is younger, higher quality than the rest of the field. A computer-generated yield map of the field clearly defines those areas.

“We're still trying to figure how to capitalize on that by picking up better quality hay bales in a different pass than from the rest of the field. With hay prices as high as they are right now, the better quality hay could be worth $40 to $50 more per ton. That may make the extra effort worthwhile.”

The yield monitor system costs about $3,000, but the data it is providing are priceless.

“On one field, we realized we were getting two-thirds of the yield off half the field,” says Rietkerk.

“It's easy to see where we're getting one ton per acre versus other areas of the field that are getting only a half-ton,” says Yager.

This also illustrates why growers are embracing yield monitors, GPS technology, and mapping — to tell precisely where there are problems.

“Like any precision ag technology, you have to prove what the yield map is telling you,” says Yager. “The problem with a low-yield area could be compaction or a sandy streak, two entirely different issues requiring two totally different solutions to rectify.”

After ascertaining the problem, economics play into the solution. “If a soil is very sandy, it only has a certain yield potential. You can apply only so much manure to improve yield potential,” Yager says.

“You can take an old nag and feed it racehorse rations, but it will never run as fast as a Thoroughbred. My philosophy is to manage soils to their potential.”

Rietkerk farms where salt content is a major issue and yield mapping helps him clearly identify those areas. The solution is often a soil amendment to leach out salts. Alfalfa is also a big user of phosphorous.

“One of the things an alfalfa yield monitor does is to give immediate information to help correct a problem quickly,” says Yager.

Rietkerk cuts alfalfa five to six times a season, and to Yager that represents five or six opportunities to correct a problem.

“Maybe you can correct a problem with a sulfur opportunity during the summer when things are a little slow, compared to the spring. You might be able to buy product and get it spread a little cheaper when things are slow.”

And, the grower may be able to see an immediate difference between the two cuttings.

Alfalfa is now the biggest field crop in California, with more than 1 million acres planted. The booming dairy industry has raised the level of importance of the forage from basically a rotational forage crop to a more important cash crop.

“For years, a lot of growers grew it for a rotation crop that afforded an opportunity to bring in a little cash through the summer to pay bills before the big cash crops like cotton came in,” says Rietkerk.

“It was not really managed as a cash crop like cotton,” says Yager. “Now, with the huge dairy demand for hay, there is good cash flow money in alfalfa. In the past, a lot of money was maybe left on the table by not managing alfalfa as intensely as we do today. By that I mean alfalfa can mine a lot of nutrients from the soil; it uses a lot of potassium and other nutrients.”

Those often were replaced only after the alfalfa was taken out for tomatoes or cotton.

“If we treated alfalfa the way we used to, we'd be throwing a lot of money under the table,” says Yager.

Rietkerk and Yager believe the alfalfa yield monitor will allow the grower to put more alfalfa cash in his pocket.

Hide comments


  • Allowed HTML tags: <em> <strong> <blockquote> <br> <p>

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.