The Ag Leader Technology cotton yield monitor system for the John Deere cotton strippers utilizes multiple optical sensors to measure cotton volumetric flow rate in the exit side of the cleaner. The sensors utilize the same technology as the cotton picker yield monitor offered by Ag Leader Technology with some modifications to optimize its performance on a cotton stripper. Volumetric flow rates from the 3 flow sensors are communicated to a PF3000 yield monitor unit in the cab of the harvester over a serial communications bus. The PF3000 stores accumulated cotton volume for both fields and individual loads within fields, and combines these volumetric values with other information to calculate total weight and average yields for fields and loads. When the PF3000 is coupled with a GPS receiver, data can be stored on a PCMCIA memory card for producing yield maps with desktop PC software.