Benefits Prove GPS Technology Pays

October 27, 2012 07:51 AM

Threefold benefits prove GPS technology pays

p40 Profits from Precision

For their senior project at Iowa State University, Clint Luellen (left), Eric Mensen (right), and two classmates equipped Tim Luellen’s tractors with GPS and then compared the costs of manually steering and GPS-guided auto-steering.

What began as a parental favor ended up changing the way Tim Luellen and his partners farm near Minburn, Iowa. Luellen’s son, Clint, and his Iowa State University (ISU) classmates Eric Mensen, Christopher Murphy and Cody Van Drie needed farmers for their senior project: a comparison of GPS-based precision farming technologies and conventional farming practices.

The elder Luellen, along with Bill Wright and Karen Wright, his partners in W L Farms, agreed to be the guinea pigs for the project, in conjunction with Derwin Van Drie’s farm near Sheldon in northwest Iowa.

"We took two farms that had no automatic row shutoffs on their planters and no GPS-based auto-steering systems, then installed GPS tracking and recording equipment on TECHNOLOGYtheir field cultivators and planters," says Clint Luellen. "The GPS information was unavailable to the tractor drivers while they were running the machines. They manually steered, raised and lowered the equipment. Once they were done, we used the data we collected to compare where they actually drove to where the precision farming equipment said they should have driven.

"Then we analyzed the costs of inputs and compared what it cost to manually control the equipment versus using precision technology to operate it," he says.

The results converted Luellen’s father from a precision farming skeptic to a precision farming advocate.

"We wrote the check to invest in auto-steer, row shutoffs and RTK guidance within a week of seeing the final numbers," he says. "The data showed the equipment would pay for itself in two years, simply by saving money on reduced inputs. It was a no-brainer."

Pencil to paper. Analysis of the project’s data shows precision guidance, auto-steering and automatic shut-offs provided benefits in three ways:

¦Increased pass-to-pass accuracy during field cultivation minimized overlapping, which saved time and reduced fuel costs.

¦Automatic row shutoffs reduced overplanting of headlands and point rows, which reduced seed costs.

¦Automatic row shutoffs also increased overall yields at harvest by minimizing barren stalks on headlands and point rows that would have been overplanted without the shutoffs.

The first benefit from precision guidance came as field cultivator performance was analyzed. Project member Eric Mensen says overlapping field cultivator passes was more expensive than expected.

"A lot of people think it’s no big deal if they occasionally overlap 3' or 4'," Mensen says. "When we compared the actual field size to the acres that were field cultivated, the cost of overlapping really showed. In some fields, they tilled an extra 5 or 10 acres. In one 220-acre field, they overtilled by 10% to 15%."

Those numbers caught the elder Luellen’s attention. "When you realize you’re overtilling by that much, applying $800 per ton anhydrous and burning $4 per gallon diesel fuel, auto-steering to minimize overlaps starts to look more economical," he says.

Improved planter accuracy was the final factor that converted Luellen to precision farming. The project highlighted the cost when the 24-row planter overlapped a couple of rows into the headland, or when it overplanted into point rows when finishing a field. "Our 24-row planter had half-width shutoffs," Luellen says. "There were fields where we had up to 12 point rows planted at 70,000 seeds per acre [twice their normal population of 35,000 seeds per acre] for an entire half-mile pass. We were wasting $325 per bag of seed corn and getting nubbins from areas we overplanted."

ISU’s Matthew Darr supervised the students’ project and says their work verifies research done by universities and precision technology companies.

"If anything, the numbers the students used in their analysis were pretty conservative," Darr says. "This is a case study with results that could apply to about any farm."

Project member Christopher Murphy says that while the per-acre cost of the technology is harder to justify on farms of less than 1,000 acres, noncash benefits might justify the expense.

"Smaller farmers might not see as quick of a payback per-acre from GPS technology, but there are other intangible benefits," Murphy says. "My family farms around 700 acres. My parents, my brother and I have full-time jobs and farm in the evenings and weekends. Being able to accurately work after dark is a huge benefit."

Participation in his son’s senior project coincided with needed equipment changes on their farm, Luellen adds.

"It was time to trade planters, so we incorporated automatic row shutoffs in the price of the new planter," he says. "This required us to go with RTK, which is more expensive. It wasn’t cheap to buy all the equipment and subscriptions. But the numbers showed that we were leaving as much as $20,000 in the field, so it wasn’t hard to spend money to save money."

"Our senior project ended up costing Dad money," says Clint Luellen. "But in the end, the numbers show he’s actually going to save a lot of money. We got an ‘A’ on the project, so it was a win-win for everybody."

Precise Planting: By the Numbers

Seniors in an Iowa State University ag systems and technology class went to the field in the 2011 crop year to study the economic efficiency of manually driven field cultivators and planters versus GPS-guided field cultivators and planters using auto-steer and automated row shutoffs. Here are the results of the planter portion of the project:



The project documented that corn planting overlap totaled 29.51 acres out of 896 acres of corn planted, with seed cost of $128.60 per acre.


At harvest, overplanted corn rows had a 10% decrease in yield: 166.5 bu. per acre versus an overall average of 185 bu. per acre. Corn price at the time of the analysis was $6 per bushel. The overlapped rows averaged $999 per acre gross return, compared with $1,110 per acre from non-overlapped field averages.


Overlapped corn acres (29.51) multiplied by the reduced yield due to overlapping ($111 per acre) showed a loss related to overlapping of $3,275.61 across the entire 896 acres of corn
in the project.



The project documented that across 1,167 acres of soybeans, overlap totaled 38.43 acres, with seed cost at $59.80 per acre.


At harvest, soybeans averaged 55 bu. per acre. Yields in overlapped rows were 10% lower than non-overlapped areas of the field: 49.5 bu. per acre. Market price for soybeans at the time was $11.86 per bushel. Overplanted rows grossed only $587.07 per acre, compared with $652.30
per acre for non-overlapped field averages.


Overlapped soybean acres (38.43) multiplied by the reduced yield due to overlapping ($65.23 per acre) produced a loss related to overlapping of $2,506.78 across the entire 1,167 acres of soybeans in the project.


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