For lawn fertilizer to be effective, it requires proper application throughout the grass. A lawn spreader requires calibration before it will distribute fertilizer in the correct amounts. Fertilizer spreaders come in two varieties: the drop spreader that "drops" fertilizer onto the earth, and a broadcast spreader, which throws fertilizer using a rotating disk. The broadcast spreader is the more difficult to calibrate, but both are possible to get to a nearly accurate spreading rate.
Mark off 100 square feet in your yard and fill the spreader with the material you are spreading.
Attach a piece of cardboard underneath the spreader to catch the fertilizer as it falls, and set the fertilizer spreader to the manufacturer settings for proper application.
Walk the spreader throughout the 100 square feet of yard, walking at the pace you will spread the fertilizer at.
Weight the material inside the cardboard trough and multiply by 10 to get the application amount for 1,000 square feet, or do the math appropriately for your yard size.
Fill your broadcast spreader with your fertilizer, enough for an area of 200 square feet. Push the spreader several feet to determine how far the spreader throws material.
Mark off an area for 200 square feet worth of fertilizer. If your broadcast spreader sprays fertilizer over a 10-foot width, mark out a 20-foot length to cover 200 feet.
Roll the broadcast spreader over the area to distribute the 200 square feet worth of fertilizer. If there is still fertilizer in the spreader after rolling over the 200-foot area, or if you use it up before covering the space, adjust the fertilizer setting while making another test run.
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Cleveland Van Cecil is a freelancer writer specializing in technology. He has been a freelance writer for three years and has published extensively on eHow.com, 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.