DEVELOPMENT OF AN AUTOMATED SYSTEM FOR SAMPLING CROP MATERIAL FROM A FORAGE HARVESTER

A modular, computer–controlled sampling system was developed to directly sample chopped forage material from a forage harvester spout. Pneumatic cylinders powered a deflector flap to redirect crop material from the spout. A hydraulic cylinder compressed deflected forage material into 35.6–cm long, 10.2–cm diameter PVC pipes, which served as miniature test silos. Timing of the pneumatic and hydraulic actuators was controlled by a programmable microcontroller. The control system included three operator inputs: travel speed, row length, and number of samples along the row for each silo; this provided flexibility to adapt to different harvesting situations. In two experiments, test–silo samples fermented for 48 days and then were separated into six size fractions. In the first experiment, a side–by–side comparison with a self–propelled plot harvester, statistically significant differences in the mass fractions of medium and small particles (indicated by low p–values in the range of 0.1 to < 0.001) were found between samples collected by both machines and their respective controls. No differences in the mass fractions of large particles were found. In the second experiment, the performance of the modular sampling system in sampling corn chopped at two theoretical lengths of cut (6.35 and 19.1 mm) and two whole–plant moisture levels (approximately 70 and 60% w.b.) was evaluated. Some significant statistical differences between automatic sampling and manual sampling were present; however, trends were inconclusive. The magnitudes of mass percentage and characteristic particle size differences were at most 8% and 1.6 mm, respectively.