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The right N rates

THE HIGH price of nitrogen fertilizer has likely got you looking closely at how to maximize your N dollars this spring. Although cutting rates may save you dollars up front, if it lowers yields and profits, it's not a wise move, agronomists say. Research done at Iowa State and the University of Illinois confirms that an increase in nitrogen prices, even with low grain prices, has little effect on the most economic or profitable rate of fertilizer N to apply to corn, grain sorghum and even small grains. For fertilizer efficiency, think least cost per bushel rather than lower costs per acre.

Making sure you apply only what your crop needs is one important cost-control strategy. But how to determine the right N rate, especially for corn production, is a topic that's been hotly debated the past two years.

Several university agronomists have been revisiting and revising the methods they use to calculate this all-important figure and recently have made a useful decision tool available to producers.

New tool for figuring rates

Iowa State University researchers joined with counterparts in Illinois, Minnesota and Wisconsin to develop a new N calculator, which they have posted online. It calculates the maximum return to N (MRTN) rate based on different nitrogen and corn prices that you input. By doing so, you can figure the most profitable N rates, based on recent N rate research data.

John Sawyer, ISU Extension soil fertility specialist, says that he and other Corn Belt state specialists started discussing N recommendations back in 2004. “We were looking at differences in methods for determining suggested N rates across states, misperceptions regarding N rate guidelines, concerns about application rates as corn yields have climbed to historic levels and current high N fertilizer prices,” he says.

Sawyer explains that the MRTN rate uses a newly developed regional approach for determining corn N rate guidelines in individual states. The current Web site includes N rate trial data for just the four states (Illinois, Iowa, Minnesota and Wisconsin) that had an adequate number of research trials available for corn following soybean and corn following corn. “These trials were conducted with spring, sidedress or split preplant/sidedress applied N, and sites were not irrigated,” he says.

“Indiana, Michigan and Ohio also were involved in developing this approach but do not yet have adequate data for calculation on the Web site,” he adds.

View the Corn Nitrogen Rate Calculator online at

Another important cost-saving strategy is to make sure you're applying N in the most efficient way possible and not wasting any high-priced plant food due to equipment faults and failures. Each of the following three products addresses a key challenge in proper fertilizer application:

  • Precise placement in the soil,
  • Consistent flow of the fertilizer, and
  • Fast application in a short time frame.

Get more precise placement

Less shank movement in the soil results in more precise fertilizer placement. That's the idea behind Thurston Manufacturing's new MaxPac AR700 AutoReset spring mechanism for Blu-Jet fertilizer applicators.

More than a simple spring cushion, this AutoReset spring will resist up to 790 lbs. of pressure at the knife tip before beginning to trip back, when pulled at 6+ mph, the manufacturer claims. After extensive product testing, the company's engineers found the highest spring pressure allowable without shearing an extensive number of knife bolts and implemented it into this design.

Used with the Blu-Jet edge-bent shank, this means less movement of the shank in hard soils and more accurate placement depth. The mechanism is designed with 10 in. of trip height to avoid clogging. After tripping, the spring forces the shank and knife back into the ground to the proper depth. Greaseless bearing pivot points provide unmatched durability and low maintenance.

The MaxPac AR700 is fully compatible with Blu-Jet strip-till components, including super 1200 coulters, spring-loaded residue managers, 1¼- × 2-in. edge-bent shanks, SealPro hillers, and rubber torsion mounted baskets.

For more information, contact Thurston Mfg. Co., Dept. FIN, Box 218, Thurston, NE 68062, 800/658-3127, visit or, or circle 203.

Keep NH3 flow consistent

Cold days and plugged knives can produce less-than-perfect anhydrous ammonia application. The result is that you either slow down and/or overapply the NH3, says Randy Litterly. That's why he developed the NH3 Equaply system, which uses a modified method for cooling anhydrous ammonia in the heat exchanger to deliver liquid anhydrous to all knives with only a very small gas coolant stream on the side.

The bolt-on kit uses a pump that boosts the pressure of NH3 coming from the nurse tank, which keeps the correct rate of N flowing to each row. An optional pressure gauge can be mounted on each knife line leaving the manifold to allow the operator to visually monitor pressure.

“This season we're offering a new hydraulic control package that simplifies how the Equaply operates,” Litterly explains. “The pump motor will now control anhydrous rates, making the system adjustment fully automatic. There's no need for the servo valve anymore.

“We don't say that producers can cut their fertilizer rates by using our system, but when they realize how much more accurate their application is with it, they'll likely be tempted to back off a bit on their rates the following year, just to see how exact they can be,” he says. “With fertilizer prices like we have this season, you just can't afford to overapply anymore.”

Price for the pump and optional gauge tree varies according to number of knives and other options, but it ranges between $12,235 and $15,200. For more information, contact aNH3 Co., Dept. FIN, 2224 Maine St., Quincy, IL 62634, 217/224-2424, visit or, or circle 204.

Cover more acres fast

The model 8120 liquid fertilizer applicator from Fast Distributing is equipped with a 60-ft. double bar that can sidedress up to 24 30-in. rows in one pass. The double bar wings are made from 4- × 6- × ¼-in. steel tubing, and the main draw beam is 10 × 10 × ¼ in. for sound construction. With the outside wings in the folded position, the 8120 also can be used as a 16-row machine. Stainless steel orifices produce a solid stream of fertilizer that sprays directly into the opening cut by the 20-in. heavy-duty coulters. Tanks are available in either 1,500- or 1,600-gal. sizes, with pumping and control systems available from Raven, John Blue, Ace or Hypro.

“We use a live adjustable hydraulic down pressure system on the wings, which allows the wings to flex up and down in rolling field conditions,” says designer and company founder Verlyn Fast. “This means consistent coulter depth and optimum placement of your fertilizer. With the new 60-ft. double bar, farmers and custom applicators can be more productive and enjoy the benefits of split application of their nitrogen.”

Other standard features include durable baked-on powder coat paint, adjustable hitch, 10,000-lb. jack stand and road light package. Various coulter spacings are also available, along with 12- and 16-row single bars.

A field-ready, 60-ft. double bar machine with a 1,600-gal. tank, John Blue ground drive pump and coulters set on 30-in. spacing retails for about $34,000. For more information, contact Fast Distributing, Dept. FIN, 54859 County Rd. 44, Mt. Lake, MN 56159, 800/772-9279, visit or, or circle 205.

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