Calibration: To calibrate a spreader, mark off an area of 1,000 sq. ft. (25′ x 40′). Assuming a spread of 8 feet, mark off 3 every spaced lanes running along the 40 ft dimension. Weight out 20 lbs of fertilizer, place in hopper and make application to test area using the setting given on the chart for the analysis being applied. Weigh remaining fertilizer to determine the actual quantity spread. Adjust meter setting as necessary to spread the number of pounds of fertilizer that will deliver 1 lb. N per 1,000 sq. ft.