Richard L. Parish | 7/28/2006 11:30:35 PM
Sometimes the lawn spreader you own may not perform like another spreader of the same brand and model, says an engineer with the LSU AgCenter.
"The spreader settings typically found on bags of fertilizer and granular pesticides usually are based on tests performed on one sample of each spreader model listed," says Dr. Dick Parish of the LSU AgCenter’s Hammond Research Station. "This procedure assumes that all spreaders of that model are identical and will thus require the same spreader settings. Unfortunately, that is not often the case – at least with homeowner spreaders."
Parish says most professional spreaders are reasonably consistent from one sample to another and can be recalibrated by the user to assure they deliver consistent rates. Most homeowner spreaders, on the other hand, cannot be recalibrated by the owner and are not consistent from one to another of the same model.
The engineer recently conducted a study that looked at four supposedly identical spreaders of each of two brands purchased from local stores. He developed settings using one spreader of each model and then used those settings to test the other three spreaders of the same model to see if they delivered the same rate. They did not.
"With one of the two brands, one spreader delivered more than four times the rate of another supposedly identical spreader at the same setting using a low rate of fertilizer," Parish says. "The distribution pattern also varied among supposedly identical spreader models."
The LSU AgCenter researcher says variations across the distribution pattern along with the variations in delivery rate caused the actual rate applied to vary greatly over the same area of lawn.
"This means that a spreader owner who follows the spreader setting recommendation on the label exactly could end up applying over four times as much fertilizer or pesticide as the recommended rate – if one of the less consistent spreader models is used." Parish says.
"Even the better spreader samples tested had significant differences in rate," he adds. "But the highest delivery rate was less than twice the lowest rate with that model."
Parish recommends homeowners actually measure the amount of material their spreader delivers and compare it with the recommended coverage on the bag of fertilizer or pesticide.
"Then correct the setting slightly if needed the next time the spreader is used," he says.
For more information on work at the LSU AgCenter’s Hammond Research Station or a variety of helpful information related to lawns and gardens and other topics, visit www.lsuagcenter.com.