To facilitate ease of use and keep transportation costs low, inorganic fertilizers are manufactured as highly concentrated sources of nutrients. This means that applicators need to accurately calculate and apply fertilizers at the appropriate rates to supply the correct amount of plant nutrients without damaging plants or causing adverse environmental effects. Broadcasting is efficient and often the method of choice in areas with perennial plants. Rotary spreaders broadcast fertilizer in a 10 to 20 foot wide path with less uniformity and rate control than drop spreaders. Either spreader type will work well for homeowners if properly calibrated and operated.
Spreaders are adjustable for different fertilizers and rates of application.
Spreader manufacturers often list calibration settings for specific fertilizers. Likewise, many fertilizer manufacturers list settings for specific spreader models. Since manufacturers cannot list calibration settings for all situations, it is good practice to calibrate the unit for your use. Set the spreader to the closest manufacturer's setting for the rate and type of fertilizer you will apply. Place 2 pints of kitty litter in the unit and spread in a continuous straight path.