Abstract: Fertilizer spreading apparatus includes a vehicle carrying a plurality of product bins, each for carrying a fertilizing product. Feeder devices are provided to meter product from the bins which is collected and spread over the field to be fertilized. A computerized control system is provided which holds a digital soil map of the location of various soil types in the field to be fertilized and is responsive to vehicle location means for determining the location of the vehicle in the field, looking up the type of soil the vehicle is currently over based on its location, and adjusting feeder operation in response thereto. The method further includes the steps of acquiring an aerial photograph of the field to provide the digital soil map and for testing the various soil types in the field for fertilizing requirements and inputting the information into the control system whereby product rates may be varied according to the soil type.