Calibrating Your Spreader

Source(s): Walter Reeves

Application of the correct amount of fertilizer and pesticide to a lawn is important! Too much fertilizer may burn the grass. Too little herbicide gives ineffective weed control.

There are many brands of lawn spreaders. Each spreader has its own method for setting the rate of application. To confuse matters even more, a spreader setting that accurately dispenses the correct fertilizer rate at one setting might not dispense the same amount of pesticide or seed at that setting.

To protect the environment and your lawn, your spreader should be calibrated for each product you use. This includes seed if you have a fescue lawn.

Calibration is not difficult. It only involves measuring a known area and then measuring the amount of product applied to that area at a certain spreader setting.

This only needs to be done one time for each product.

The only equipment you will need is a bathroom scale, a bucket and a tape measure.

To calibrate a spreader

1. Set your spreader at about 1/3 open. (Example: if the spreader has settings from #1 to #9, set it at the #3.)

2. Put two to three pounds of clean sand in the spreader; walk forward and let it dispense for ten to twenty feet. Visually note the width of the swath of sand applied by the spreader. Stop and measure the width of the swath. Remove remaining sand.

Swath width:________feet

NOTE: ‘Drop’ spreaders are easy; the swath width is the width of the spreader body.

3. Divide the swath width into 1000.

1000 square feet =_______feet width from step #2

4. Put ten pounds of the product you wish to apply in the spreader. Walk forward and operate the spreader for the number of feet determined in step #3.

5. Stop. Remove product from spreader and weigh it. Subtract this weight from ten pounds. The result is the number of pounds of the product applied at that spreader setting per 1000 square feet.

Ten pounds minus what is left =________ (amount of product applied per 1000 square feet)

6. Adjust the spreader opening up or down to achieve the application rate you wish for that product. (Repeating steps #4 – #5.) Use a felt tip marker to write on the spreader and indicate the proper setting.


#4 setting = six pounds of 16-48 fertilizer/1000 square feet

1.Hold an Empty bucket in your hand. Step on the scale and note the weight shown.
2.Scoop out of the bag approximately the weight of product you want and place in bucket.
3.Re-weigh yourself holding the bucket.
4.Add or subtract material from the bucket, re-weighing each time, until you have the right amount.




Step by Step ExampleAction/Calculation

1. You want to apply six pounds of fescue seed per 1000 square feet.

2. Spreader settings are #1 – #10Set spreader to #3

3. Walk 20 feet with sand in spreader.Measure with tape measure.

4. Divide ten feet swath width into 1000.1000 sq. ft. / 10 ft. = 100 ft. to walk 10 ft.

5. Place ten pounds of fescue seed in spreader and walk 100 feet. Weigh remaining seed. There are six pounds remaining.You have applied only four pounds of seed to 1000 square feet at spreader setting #3. Need to adjust spreader opening.

6. Adjust spreader to #4 opening. Put ten pounds of seed in and walk another 100 feet. Four pounds of seed remain in spreader.You have applied six pounds of seed per 1000 square feet.Mark on spreader #4 = six pounds fescue/1000 square feet.

Resource(s): Lawns in Georgia

Center Publication Number: 11

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