Follow the calibration steps outlined above for drop spreaders. Granular calibration tips Drop spreaders are more precise. There is little chance of product application to non-target areas. However, small steering errors can easily lead to missed or double-covered strips. Also, drop spreaders may clog in wet grass.
Rotary spreaders are faster than drop spreaders but are more difficult to calibrate.
Product distribution is less uniform, and wind may blow the product off the intended area. The application rate for granular spreaders depends on the granule size, the spreader setting and the speed at which the operator walks. Spreader calibration must be done for each product and applicator who uses the spreader. Always sweep up and reuse the product used for calibration. Use a header strip in areas where the spreader must be turned around.