Manure Spreader Calibration

Managing the nutrient load as you’re spreading manure on your fields is important for the environment, and for the bottom line. This is only achieved if the spreader is calibrated for the right application amount.

Rory Lewandowski is an Extension educator at Ohio State University. He says the application rate for manure spreaders is generally expressed as tons-per-acre or gallons-per-acre.

When calibrating for gallons-per-acre, he says measuring capacity by weight is the most accurate.

"We could figure the density of manure by taking 5-gallon pail samples, weighing them and figuring out that density, then multiplying that density times weight to get a gallonage. The second method that could be used would be to use a mathematical formula to get volume," says Lewandowski. "So if we know our length, our width and height of our spreader, we can figure out a volume in cubic feet, and then there are constants that we can multiply that by."

Pin down some tarps in the field to help calibrate solid manure spreaders.

"We would make sure that they’re placed far enough out in the field so that when we go over them that we’re at our normal operating speed that we’re spreading at. We’re going to drive over those tarps, we’d usually do this multiple times, 3-4 times, maybe 3-4 different tarps," he says. "We collect those tarps, then we find that we’ve got 13 lbs. over a given area, and then there’s a constant again that we multiply by so we’ve got a formula. We’ll come up with a tons-per-acre type of figure."

He says a manure nutrient analysis is another important part of the puzzle so you know what’s going into the soil.