If it is too large, reduce the opening. After reaching this final setting, repeat the procedure at least one more time to be sure that you are correct. The same calibration procedure is used for fertilizer, seeds, or granular pesticide you want to apply. Check the spreader to make certain all parts are operating properly. Make the application on bare ground or a hard surface where the width of the surface covered by the material can be measured.
More material is applied toward the center and less at the edges.
If the application width is 12 feet, only about 8 feet is receiving approximately the same application rate. The other 2 feet on each edge, respectively, receives much less material than the center area. Mark off a test distance which when multiplied by the effective width will give you a 1000 square foot area. Then the test strip will be 100 feet long since width times length is 10 x 100 or 1000 square feet. Determine the amount of material to be applied.