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Pressurized NH3 a game changer

Accurate, cold-weather,
variable-rate application of anhydrous ammonia is a dramatic step forward for
Doug Zink, a farmer in Carrington, North Dakota.

He’s taken up the challenge
with the Maxflow VRC. The machine pumps liquid NH3 into the soil according to a
prescription map, at up to 170 pounds per acre. The operator has sectional
control, a manual foot switch to minimize loss at turns, and a field that is
ready to seed when the work is through.

“This is the best anhydrous
applicator I’ve ever had, and I’ve had a lot of them,” Zink says. “Most of the
time, things don’t really live up to what you’re told. But this does.”

Zink applies the NH3 at 9
mph with a new 42-foot vertical tillage coulter, the Salford RTS. It will cut
through 2 inches of frost and up to 1 foot of snow. In less than two weeks,
Zink had fertilized about 8,000 acres of soybean residue. He was going through a
1,500- gallon tank of NH3 every 90 minutes.

“You can put on 140 pounds
of actual nitrogen or just 40 pounds at 9 mph. It’s just so accurate,” Zink
says. “You don’t have to worry about anything.” The cab tells the operator how
much is in the tank. When there’s 10% left, an alarm goes off.

The key to the system is
high pressure, keeping the NH3 liquid until it is sealed in the ground,
according to Cameron Stewart, president of MaX-Quip. The company specializes in
handling and metering compressed gases from many industries. Pressurized liquid
NH3 is easier to handle and can be metered more accurately. It eliminates vapor
loss and opener freezing.

Continuous pressure is
generated by the tractor’s hydraulics, tied into a MaX-Quip positive
displacement van pump driven by a hydraulic motor. The pump is mounted close to
the nurse tank with the intake below the nurse tank belly. Varying the motor
speed varies the flow rate.

“Higher pressure with
smaller lines lets you accurately deal with reduced rates at the low end and
accurately push more product through at high rates,” states Zink.

An automatic rate
controller, using signals from a flow meter and a ground speed indicator, can
adjust the motor speed on-the-go. The rate can also be varied by a task
controller with a map and GPS signal. On-off valves on the distribution
manifold keep the system fully pressurized.

“If you only need 30 pounds,
you now can get it with consistency and accuracy. At all rates, high manifold
pressure is easier to handle than low manifold pressure,” Stewart says. “For
variable rate, high pressure provides almost instant response from zone to

Normally, he says, about 2%
of NH3 is consumed in the cooling and vapor line. The Maxflow requires neither,
creating an instant savings for the grower.

System pressure is always
higher than tank pressure. An in-line, pressure-compensated valve keeps NH3 in
a liquid state in the flow meter to ensure accuracy. The system is always
metering liquid, never vapor.

“We get no frost on the
lines, no frozen openers, and no footballs being dragged around in the field,”
says Zink. “The result is accurate NH3 placement where we want it, along with
better sealing.”

The pressurized system can
apply approximately 2% to 2.5% of the nurse tank storage capacity per minute. A
1,500-gallon nurse tank applies 30 to 37.5 gallons per minute.

Electric valves can be
installed on each manifold. These provide section control, either manual or
integrated into an automatic section-control system. Manifold valves also
provide a quick on-off response time. The system sells for $16,000 to $22,000.
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