A harvester has an operator cab, a motor, a carriage driven by the motor, a crop cutter and collector, a processing body, and an ultra-low flow agricultural forage preservative applicator system for applying a biological solution to forage during harvesting. The forage preservative applicator has a biological solution reservoir, a flush reservoir, a peristaltic pump, a valve operative to either couple the pump with the biological solution or the flush solution, and a dispensing tube, where the biological fluid containing pathways are of functionally like cross-section in the region between the biological solution reservoir outlet and the dispensing tube outlet. A flow detector which does not obstruct the fluid pathway is provided to monitor biological solution flow rate, and a moisture detector and harvest rate detector may be used for automatic control.
