From staff reports

The three factors that determine the sprayer application rate are speed, nozzle spacing and nozzle output, according to Robert N. Klein, University of Nebraska-Lincoln extension cropping systems specialist.

Klein talked about spraying fields at a recent Joplin meeting.

For example, a sprayer moving a mile per hour will travel 5,280 feet an hour or 88 feet per minute.

To determine coverage, test each nozzle on the sprayer to measure output. Each nozzle should be within 10 percent of the manufacturer's rating for that nozzle. Replace any nozzle delivering 5 percent above or below the average delivery rate for all the nozzles on the unit, he said.

The amount of fluid flowing through a spray orifice varies with its density. All nozzle tabulations are based on spraying water that weighs 8.34 pounds per gallon, he said.

A sprayer must be checked as it operates to assure the spray provides adequate overlap to prevent gaps in coverage, Klein said.

Finer droplets are more prone to drift damage that increases the higher the boom is above the ground.

A fine spray is more prone to drift, but gets more of the product through leaves than do larger droplets that can collect on leaves, he said.

Reducing in half the size of the spray particle size means getting eight times the number of droplets, he said. Crops planted with 30 inches between rows can be sprayed with larger droplets, he said.

Klein said he likes sprayer nozzles tilted to the back to get more coverage. "You never angle a nozzle forward because it creates a lot of drift," he said.

He warned against operating a sprayer at 4 mph or slower to measure drift from spraying. "That is too slow, you could be traveling 10 mph when you spray," he said.

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