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N savings by the row

Precision Agriculture technologies can help take a bite out of higher nitrogen costs. Just ask Mike, Bob and Jim Ellis, who grow several thousand acres of corn in northern Kentucky, near Eminence. They estimate that this year they reduced N costs at least 10% with a new farm-built sidedress setup that enables them to shut off individual rows. This allows them to reduce waste from fertilizer overlaps along field borders and waterways.

The rig is harnessed to an electronic controller linked to a Wide Area Augmentation System (WAAS) GPS antenna that automatically turns off coulter drop tubes as they pass into areas that already have been fertilized, or in waterways or outside of the field where fertilizer also would be wasted.

The Ellis farm is dominated by small, irregularly shaped fields, with lots of grass waterways, so being able to shut off drop tubes one by one has a big payoff.

“Conservatively, it was close to 12 to 12.5% in savings in N,” or about $10/acre, Mike Ellis says. The savings more than paid for the $3,000 to $3,500 cost of the upgrade.

“As we get to end rows in triangular-shaped fields, there is no overlap,” he says. “Once the border rows are put in, when you do the interior rows, it turns off automatically at the border rows.”

In 2009, the dollar savings will be about 50% greater than in 2008, given what's happened to the price of N in recent months. In mid-summer, the Ellises paid $0.50 more per pound of actual N for the 32% urea ammonium nitrate (UAN) solution they will use to fertilize next year's crop than they paid for their 2008 crop N.

Manufacturers take note

Although the Ellises opted for a do-it-yourself approach, nitrogen application equipment manufacturers have been eyeing the market for rigs with section control as nitrogen prices have heated up.

Capstan Ag Systems, for example, has offered section-control kits for both liquid and anhydrous ammonia application bars for several years. But interest among customers has been relatively modest until recently, says Steve Willey of Capstan.

“As fertilizer prices have exploded, we are seeing a lot of interest,” he says. “Swath control in fertilizer is the big deal right now. The savings really add up when they [growers] go to swath control.”

Thurston Manufacturing Company, which builds the Blu-Jet line of fertilizer applicators, has noticed a similar trend, says Nick Jensen, marketing vice president for Thurston. The company introduced liquid application bars with individual row shutoffs in 2005 and offers anhydrous and liquid applicators in five- and seven-section configurations.

“As the price of fertilizer increases, we see the demand for section control increasing as well,” Jansen says.

Granular fertilizer application equipment manufacturers also are taking note of the trend toward swath control. Paul Haefner of AGCO's Ag Chem Application Equipment Division says the company will add multiple sections to air booms for TerraGator applicators within the next two years. Current 70-ft. air booms have right and left sections.

The Ellis rig

The Ellises turned to Scott Shearer, a precision ag expert at the University of Kentucky, to help them configure their 16-row Blu-Jet sidedress coulter cart for individual row shutoffs. They also have worked with Shearer to adopt individual planter row shutoffs, as well as a sprayer with 30 control sections. These innovations have resulted in an estimated 10 to 15% savings in seed and herbicides.

Shearer suggested that they use air-actuated solenoids powered by a small air compressor to turn on and off diaphragm valves for each row. This was less costly than direct-acting electric solenoid valves.

Each of the solenoids, which are housed in a protective black box mounted on the toolbar, powers a pair of diaphragm valves plumbed in series. The first valve is the on/off switch for the fertilizer supply line to the orifice feeding fertilizer to the coulter drop tube. The second diaphragm, which turns on when the first is turned off, shunts fertilizer back to the supply tank. This is needed because the rig's constant-flow piston pump would otherwise redistribute the fertilizer from the closed orifice to the remaining open orifices, eliminating any savings. This also eliminates the possibility of blowing out lines, or the pump, if all drops were shut off.

Off-the-shelf options

Capstan offers section kits for both liquid and anhydrous application rigs. The kits use electronic solenoids to turn on and off individual rows/shanks or wider sections, depending on controller capabilities. The solenoids, which use pulse-metering technology used in Capstan's AIM Command and SharpShooter spraying systems, also can drive variable-rate applications with a 25:1 rate range.

Capstan's N-Ject 1615 ammonia kit for 16-knife bars includes an eight-section manifold and 16 solenoids, which provide individual knife shutoff, depending on controller capability. The manifold serves as a cooling tower and distribution head. It has a suggested retail price of $11,800. An N-Ject LF (liquid fertilizer) kit for a 16-row applicator has a suggested retail price of $7,300. Kits include manifolds with solenoids, a wiring package and a computer module with software. For more information, contact Capstan Ag Systems Inc., Dept. FIN, 101 N. Kansas Ave., Topeka, KS 66603, 785/232-4477, visit or, or circle 108.

In 2009, Capstan plans to introduce a software/hardware upgrade that will allow rigs to compensate for turns, which will allow varying rates to be applied along a boom/applicator bar as it turns. This will provide a uniform application instead of varying rates from speed differences that occur during turns without this compensation, Willey says.

Blue-Jet's by-the-row liquid fertilizer option adds about $4,000 to the cost of a three- or five-section 16-row bar for extra plumbing and electric ball valves, according to Thurston's Iowa distributor, Brokaw Supply Company, Ft. Dodge. For more information about the applicator, contact Thurston Manufacturing Company, Dept. FIN, Box 218, Thurston, NE 68062, 800/658-3127, visit or, or circle 109.

In addition to selling Blue-Jet's section-control fertilizer application options, Brokaw introduced both liquid and anhydrous section retrofit kits at the 2008 Farm Progress Show. Price of a six-section anhydrous retrofit kit (every four rows on a 24-row bar) is $8,000. The units are set up for plug-and-play section control with GreenStar 2, AgLeader Insight and Raven Invizio Pro controllers.

Full system costs

Building or buying a sectioned applicator reflects only a portion of the cost of adopting this technology. The Ellises, for example, already had a real-time kinematic (RTK) guidance system, as well as a John Deere GreenStar controller and a Topcon X20 30-section controller. Building a system with RTK accuracy from scratch could cost $30,000 or more. Depending on the width of the sections, guidance systems with less than RTK accuracy may be adequate, which would reduce the cost.

There are additional costs associated with the system, including software for creating maps, and the time and energy required to create them. The Ellises have created field maps using EASi Suite from Mapshots and Site Mate from Farm Works. They learned a lesson in accuracy this year when they discovered that some mapped waterways and other field features didn't match up with reality. It turned out that these features were mapped at lower accuracies than those used for field boundaries, which had been mapped earlier.

Future “section” directions

Sectioning of nitrogen applicators is likely to receive more attention as more growers become aware of the potential for cost savings.

“In the future, I think farmers are going to demand this capability,” says Shearer of the University of Kentucky. “Five to 10% savings on N is enough for many to cash flow the investment in technology. Our experience indicates that many of these systems will have a payback period of two to three years in a worse-case scenario.”

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