A feed system for a biomass collection device uses a conveyor for dropping a flow comprising a mixture of denser or heavier biomass to be collected such as cobs, and less dense or lighter biomass residue such as leaf trash, through a space, and rotary feed apparatus below for receiving the flow, operable for propelling the received flow into a collection device, in combination with a fan configured and operable for directing a flow of air along a second path intersecting the first path in a manner to divert at least a substantial portion of the less dense or lighter biomass residue away from the feed apparatus, while allowing substantially all of the denser or heavier biomass to continue along the first path to the feed apparatus for feeding into the collection device. Distribution apparatus along the second path can then be used to spread the diverted biomass.