Spraying should account for very little energy used on the farm—just two tenths of a gallon per acre. But a poor spraying job can lead to a second trip, which not only makes spraying energy-intensive but economically inefficient as well, warns Bill Casady, University of Missouri agricultural engineer.

“There are several potential pitfalls to efficient application of crop protection materials, but the good news is that they can all be managed,” he says. Along with a poorly timed application, other high-cost inefficiencies come from overlap, poor calibration and off-target placement, he adds. “Round these out with poor spray distribution or nozzle selection and there is potentially a lot of room for improvement.”

Keys to cost saving

1. Calibrate. There’s no question that taking the time to calibrate your sprayer is well worth while, Casady says. “With little or no calibration, it is estimated that as few as 5% of spray events are within the plus or minus 5% of target rates considered reasonable accuracy.”

The surprising statistics from some research show that crop protection materials are often over-applied by more than 20% due to overlapping and poorly calibrated sprayers, he notes. “A herbicide program with a projected material cost of $20 per acre may cost as much as an extra $4 per acre for the waste created by overlap. Similarly, a $50 program might cost an additional $10 per acre. Improving accuracy can save a potential $10,000 over a thousand acres.”

A simple sprayer calibration can make huge differences, and it might even be worth investing in a light-bar for guiding sprayers through the field, says the ag engineer. "The perfect time to calibrate is while the sprayer is still clean at the beginning of the season.

2. Replace nozzles. Start with a new set of nozzles, especially if you covered a lot of acres last season. "As nozzles wear, their output trends higher. And wear is usually greater when you’ve applied products in suspension, versus soluble products, he says. “Wear rates are also higher for low-capacity nozzles and those operated at high pressures.”

Nozzles should generally be replaced as a set, unless you’re having a mechanical problem or damage with an individual nozzle. Stainless steel, hardened stainless steel and plastic nozzles have the longest life, so they’re probably worth the added cost, especially if you don’t like changing them a lot, he adds.

3. Recalibrate. Consider a recalibration whenever you do a thorough sprayer cleanup, says Casady. It doesn’t need to require more than about 20 minutes. If that single recalibration saves 5% on say the last 500 acres sprayed at $25 per acre, then that twenty minutes worth of work would come in at about $1,875 per hour."

A good reference is a University of Missouri bulletin called Calibrating Field Sprayers.