Method and apparatus for spreading fertilizer

Claim 1

A fertilizer spreading apparatus, comprising a wheeled vehicle (20), product bins (22-31) mounted on said vehicle, said bins holding a product to be applied to a field to be fertilized, feeder means (33, 34, 42-49) mounted on said vehicle and associated with said product bins, said feeder means being operative in response to a feeder control signal for dispensing the product at a selected rate from said bins, collecting means (70) for collecting the product dispensed from said bins, spreading means (75), and a control means mounted on said vehicle for generating said feeder control signal to control the rate of dispensation of the product, said control means further comprising: (a) digital soil map means (10) for indicating the distribution of the different soil types in said field to be fertilized; (b) locator means (114) for producing field coordinate signals for indicating the position of said vehicle relative to said field as it moves about said field; (c) speed indicator means for indicating the speed of said vehicle as it moves about said field; and (d) computer means (100) responsive to said soil map means, to said locator means and to said speed indicator means for controlling the generation of said feeder control signal according to the location of the vehicle in the field so that each of said products are applied at different rates corresponding to said different soil types in the field.

Claim 2

A method for spreading fertilizer from a wheeled vehicle (20) carrying a plurality of products in a plurality of product bins (22-31) comprising the steps of: (a) acquiring an infrared photograph of the field; (b) providing a digital soil map, (10) at said vehicle; (c) determining the location (114)of said vehicle in said field and a corresponding position on said map. (d) determining from the soil map the type of soil where said vehicle is located; (e) determining the product rate at which the product should be applied to said field based on the type of product, the needs of said soil type determined in step (d) and the vehicle's speed; and (f) feeding (33, 34, 42-49), collecting (70) and spreading (75) said products from said product bins at dispensing rates proportionate to said determined product rates.