Frequently Asked Questions: Calibrate your Fertilizer Spreader, Answers for Homeowners


Calibrating Rotary Spreaders


Start by gathering the materials needed to calibrate your drop spreader: Tape Measure, Scale, Bucket and Scoop, and Hand Calculator.





Now, for the Math:



With the information gathered you can figure out the rate your spreader is delivering.

Calculation 1: Calculate Your Spreader's Actual Delivery Rate

Calculation 2: Desired Delivery Rate

In New Jersey, we are allowed to apply up to 0.9 lbs of N/1000 sq ft in a single application. Since you will be making 2 passes, the desired rate would be half that, or 0.45 lbs of N/1000 sq ft.

Now compare the actual rate your spreader is delivering (Calculation 1) to the rate you desire (Calculation 2).

If Calculation 1 is smaller than Calculation 2, open the spreader holes wider and repeat the test.

If Calculation 1 is larger than Calculation 2, close down the spreader holes and repeat the test.

Ideally, repeat the test until the rate you are actually delivering equals or is very close to the rate you desire to deliver.



Now that your Fertilizer Spreader is calibrated, you can fertilize your lawn!