How to Calibrate a Fertilizer Spreader


Fertilizer is a major requirement for a healthy lawn, and the best way to apply fertilizer is by using either a drop or rotary spreader. Although both drop spreaders, which release fertilizer through the bottom of the spreader, and rotary spreaders that broadcast fertilizer with a throwing arm have preset application controls, these are not always accurate. Calibrating a spreader before fertilizer application ensures the right rate of fertilizer is left on your lawn, and prevents burn marks and underdeveloped grass.

Drop spreader

Step 1

Measure and mark off an area of 100 square feet on a flat surface recommends the University of Florida. This area will be the testing ground for your spreader.

Step 2

Fill your drop spreader with fertilizer and set the spreader to the correct application rate on the controls.

Step 3

Walk the spreader slowly over the marked off area, at the same speed you will walk the lawn recommends the University of Texas A & M. Open the application doors when entering the marked off area, and close the doors once you leave.

Step 4

Sweep up the fertilizer and collect it into a pan. Weigh the fertilizer and times the weight by 10 for 1,000 square feet says the Virginia Cooperative Extension. Apply fertilizer at 1 pound of nitrogen per 1,000 square feet of lawn.

Rotary Spreader

Step 1

Fill the rotary spreader with half the desired amount of fertilizer you wish to apply. Test the distance of the rotary spreaders throwing width on a flat, sweepable surface. Mark off and area that equals out to 1,000 square feet, using the throwing width times length to equal 1,000 ie. 10 throwing feet times 100 feet length equals 1,000 square feet says the University of Florida Extension.

Step 2

Adjust the spreader to the lowest setting and begin pushing the spreader through the middle of the testing area. Open the spreader as you move down the testing strip.

Step 3

Weight the amount of fertilizer left inside the spreader after applying the 1,000 feet, and subtract it from the initial weight of fertilizer you placed into the device to determine the weight of fertilizer application per 1,000 feet. Repeat the test run opening the spreader at higher settings until you find the correct application rate.

Things You'll Need

  • Fertilizer
  • Broom
  • Measuring tape
  • Fertilizer spreader
  • Pan
  • Scale


  • University of Florida Extension: How to Calibrate Your Fertilizer Spreader
  • University of Texas A & M: Spreader Calibration
  • Virginia Cooperative Extension: Calibrating Your Lawn Spreader
Keywords: fertilizer spreader, spreading fertilizer, drop rotary spreader

About this Author

Cleveland Van Cecil is a freelancer writer specializing in technology. He has been a freelance writer for three years and has published extensively on, writing articles on subjects as diverse as boat motors and hydroponic gardening. Van Cecil has a Bachelor of Arts in liberal arts from Baldwin-Wallace College.