By Brad S. Fresenburg
University of Missouri Extension has unveiled a free web application to help homeowners apply the right amount of lawn fertilizer.
The Lawn Fertilizer Calculator, available at agebb.missouri.edu/fertcalc, helps you determine how much fertilizer you need to buy, says MU Extension horticulture specialist Brad Fresenburg.
The first step is figuring square footage of lawns. Homeowners can measure their lawns using conventional methods, or take advantage of free satellite mapping applications that let users figure square footage by setting virtual anchors to mark lawn corners.
Entering the square footage and other information enables the Lawn Fertilizer Calculator to determine how much fertilizer you need to buy and the proper application rate in pounds per 1,000 square feet.
“The objective is to get homeowners to measure or know the square footage of their lawns so that they buy the correct amount per unit area, not overapplying or underapplying,” Fresenburg says.
“Apply only what fertilizer is needed to maintain good water quality for your community,” adds Bob Broz, MU Extension water quality specialist.
Using the right amount of fertilizer saves consumers money, Broz says. It also reduces the risk of applying too much fertilizer. “There is less chance for runoff or leaching of nutrients into the ground and surface water when we do not overapply. Excessive nutrients in the water create high levels of algae, which can impair aquatic habitat.”
For best results, Broz recommends a soil test to determine what fertilizer to buy. Soil test recommendations can be entered into the calculator to determine the proper amount and application rate for your lawn.
Fresenburg, Broz, MU environmental economics researcher Laura McCann and MU Extension system administrator John Travlos created the web application over the past year. The design is optimized for mobile devices.
Support for the project came from the National Institute of Food and Agriculture’s National Integrated Water Quality Program; MU Extension; and the Missouri Agricultural Experiment Station, which is part of the MU College of Agriculture, Food and Natural Resources.