Calibrate Your Spreader for Accurate Fertilizer Applications

Article By: Matthew Lenhardt
Citrus County Horticulture Extension Agent
January 27, 2010

The first turf or ornamental fertilizer application of the year should occur after the last chance of frost, depending on Mother Nature. Fertilizing too early and “pushing” growth can promote spring green-up in turf or bud growth in plants that may be injured if our area has a late frost. Calibrating your spreader is an important step to accurately determine if you are applying the correct amounts of fertilizer or other granular products. Some fertilizers will state on the bag what setting is recommended for the correct amount of fertilizer to be applied by a particular spreader, making calibration easy. Although, since not all granular fertilizers or pesticide products have this information, here are some steps that will help with calibration.

The first step is to determine the amount of the product that is recommended to cover 1000 square feet. This information should be stated on the fertilizer label. Next, take a measuring cup that is used only for fertilizer and weigh the amount required for 1000 square feet and pour that amount into the spreader’s hopper. The next step is to measure out a set square footage, typically 1000 square feet which can be measured by using a measuring wheel or walking off a 20’ X 50’ or 25’ X 40’ area, and apply the product over the test area. The setting is correct if the product covered the area completely without any left over fertilizer in the hopper. Adjustments may be needed to open or close the spreader opening if there was too much or not enough fertilizer to cover the test area. Keep in mind that a consistent walking speed of the applicator and the product’s granule size can influence the amount of product that will be applied in the test area.

The next step is to determine the square footage of your lawn and apply the fertilizer at the recommended rate. Remember when applying fertilizer, deliver the product to the target area avoiding non-target surfaces such as roads or sidewalks, check the calibration frequently, check for uneven fertilizer appearance, and operate your equipment safely.

For more information on fertilizers, I will be offering a course called “Fertilizer Basics” at the Citrus County Extension office in Lecanto on February 10, 2009, at 1 p.m. Seating is limited. Anyone interested is asked to please register in advance by calling the Citrus County Extension office at (352) 527-5700. We are located in the Citrus County government complex at 3650 W. Sovereign Path, Ste.1, Lecanto, FL, 34461. As a part of the University of Florida we are research information based program available to all.