Fuente: Wipo "precision farming" An improved system for tracking the application of crops and field amendments being applied to fields is disclosed. A series of passive communication devices are included in products being applied to the field. As seed and other products are supplied to the field, the passive communication devices are delivered to the field as well. A reader is mounted to the agricultural vehicle and is in communication with the passive devices to read data stored on each device. The data may include the type and variety of product in which the passive devices were supplied. A controller on the vehicle receives data from the reader to identify what product has been applied to the field. The controller may store data on any additional product subsequently applied to the field and/or may verify that subsequent product is acceptable for application to a crop in the field prior to application.