System and method for adjusting air flow in air seeding applications

an air seeder, a system for maintaining an appropriate air flow in an air stream, the system comprising:

• a fan operative to provide an air flow to an air stream, wherein the air stream passes through a distribution network to carry agricultural materials for distribution across a width of a seeding implement;
• at least one tank containing a granular agricultural material;
• a metering device operatively connected to the at least one tank and operative to dispense agricultural material contained in the tank into the air stream;
• wherein a rotational speed of the metering device is directly proportional to a ground speed of the air seeder such that a per acre application rate dispensed is substantially constant as the ground speed varies,
• a microprocessor operatively connected to the air seeder such that the microprocessor receives signals indicating the rotational speed of the metering device and the ground speed;
• a fan control operatively connected to the microprocessor and operative to adjust a speed of the fan to vary the air flow in the air stream in response to signals from the microprocessor;
• wherein the system is calibrated such that a known weight of agricultural material is dispensed into the air stream for each revolution of the metering device whereby the rotational speed of the metering device multiplied by the known weight per revolution results in a known per minute rate of agricultural material being dispensed into the air stream;
• and
• wherein the microprocessor is programmed to derive an appropriate fan speed for the per minute rate of agricultural material being dispensed into the air stream and send a signal to the fan control to adjust the speed of the fan to correspond to the appropriate fan speed.