When Alan Madison bought his GPS equipment and yield monitor a few years ago, he figured it was strictly for site-specific recording of corn and soybean yields.

But last spring the Princeton, IL, producer used the GPS receiver when planting, and used both the GPS and yield monitor when sidedressing nitrogen.

Like a growing number of enterprising farmers, Madison is now “double- and triple cropping” his global positioning and monitoring equipment.

“Last spring we used the GPS to map each field, showing the corn hybrid or soybean varieties planted in those fields (each hybrid or variety is designated as a ‘load’ on the monitor),” Madison explains. “Then, after harvest, we overlaid the yield maps on the variety maps so we could see how each performed. We also overlaid soil-type maps on both the yield maps and the variety maps to see how those factors matched up.”

Madison, who sidedresses the majority of his nitrogen, wanted to try variable-rate application when sidedressing.

“We started out by looking at the soil-type map for each farm,” Madison notes. “We used those maps to determine where to take pre-sidedress samples for soil nitrate levels. Our fertilizer supplier took the samples using geo-referencing.

“It then made PC data cards for variable-rate application so the yield monitor could be used to apply nitrogen on a variable-rate basis.”

But at that point a snag developed. “There was a problem with the Raven controller reading the Ag Leader monitor,” Madison says. “Fortunately, James Schoff and Todd Peterson of Ag View FS, with cooperation from Ag Leader, were able to solve the problem. We had smooth going from then on.”

Last spring Madison varied the sidedress amounts from 45 to 90 lbs/acre on corn following soybeans and from 45 to 120 lbs/acre on corn following corn.

Cleghorn, IA, producer Tom Oswald says he's sold on the value of making site verification maps of field activities.

“I'm not a large-acreage farmer and feel I need to work the GPS and yield monitor equipment as much as possible,” Oswald notes. “To me, having that equipment setting in the shed during crop production seasons is a waste.”

Last spring, Oswald used the GPS receiver and yield monitor on three different tractors. He mapped preplant nitrogen application (locations and amounts), corn hybrid and soybean variety plantings (locations and populations), herbicide spraying (products, locations and amounts) and sidedress nitrogen (locations and amounts).

At Hartland, MN, Ted Thisius has used his GPS receiver and yield monitor in multiple ways.

“Last spring we mapped our preplant nitrogen application,” he reports. “Then at corn planting we mapped both our starter fertilizer and the hybrids we planted. We used the same planter for soybeans and mapped the bean varieties.”

Thisius has also made maps that show the locations of tile lines in his various fields.

During the off-season Thisius works for L & D Ag Service in Hartland. That firm sells Ag Leader yield monitors and related gear.

“We have customers who are using their GPS and yield monitors when spraying herbicides,” says Thisius. “They make maps that show the products, locations and rates.

“We also have customers who use their receivers and monitors when spreading liquid manure. The manure applicators have flow meters … and information from the meters transfers to tractors, where it is recorded by monitors. Those producers map the locations and rates of manure applied.”

Farmers are using GPS in other ways, too, points out Doug Gardner, GIS (geographic information system) specialist with Pioneer Hi-Bred. “They are making GPS-based records of field boundaries, soil types and scouting reports.

“Remember that GPS output also includes a time stamp,” he says. “Time-specific and site-specific weather information and records of field operations can help explain yield variation on a yield map.”

As we get into more identity-preserved crop production, he adds, farmers will need detailed records of each field under contract. “GPS receivers and yield monitors can verify information end-users will want, including hybrids or varieties planted, planting history, field isolation and inputs applied.”

Computer Can Replace Monitor

Gary Dau, a Sheridan, IL, producer, has used his GPS receiver and a hand-held computer — rather than his yield monitor — to map varieties.

“We have a 16-row planter and I wanted to compare eight rows of one variety against eight rows of another across an entire field,” Dau explains. “Making a map of a split-planter comparison is not practical with a yield monitor but can be done with a computer. We used HGIS software. Then, after harvest, we laid the variety maps on the yield maps for analysis.”

Using a computer, plus GPS, also has an advantage over a yield monitor when mapping herbicide spraying, points out Tom Niewohner, a farmer and owner of Agri-Tech Solutions, Onawa, IA. (Niewohner retails both yield monitors and HGIS software, and uses both in his farming operation.) “HGIS can log a swath map, showing you where you've sprayed and if you had any skips or overlaps,” he notes.

Current yield monitors cannot easily produce split-planter maps, and they also lack screen resolution to see small skips and overlaps when spraying, says Niewohner.

There's another benefit with the computer, he notes. At harvest you can take it, plus the hybrid or variety map, into the combine and connect it to the GPS. You can then see, on the spot, which hybrid or variety is being harvested and how it's yielding. You can do the same with herbicide, insecticide or fertilizer maps, which are helpful if you are comparing products or rates.

HGIS software, when used on a laptop or inexpensive Windows CE computer, can also geo-reference such things as boundary maps, soil samples, tile lines and scouting reports, Niewohner notes.

For more information on the software, phone Niewohner at 712-423-3934 or e-mail: tom@farmgps.com.