Statistical Process Control for Monitoring Soybean Seed Quality During Mechanical Harvest

Seed moisture content (SMC) fluctuations and machine adjustments during mechanical harvesting are associatedwith soybean seed quality and process variability. This study aimed to monitor the physical and physiological quality of soybean seeds and evaluate process variability during mechanical harvesting using Statistical Process Control (SPC) tools. Seed samples were collected at pre-established intervals from two harvesting systems operating in the same production field. Seed moisture content, purity, mechanical damage, germination, and vigor were evaluated throughout the harvesting operation. The average SMC was 15.8%, exceeding the range commonly recommended for soybean seed harvesting. Temporal fluctuations in SMC were associated with adjustments in Cylinder Rotation Speed (CRS) and Cylinder Opening (CO), which coincided with differences in process stability between the evaluated harvesting systems. Control charts identified periods of instability and out-of-control observations associated with changes in moisture conditions, machine adjustments, and operator interventions. Under the evaluated conditions, the harvesting system represented by Combine A was associated with greater process stability and higher values for purity, germination, accelerated aging, and seedling emergence. Although mechanical damage did not differ between harvesting systems, physiological tests were more sensitive in detecting differences associated with harvesting conditions. Statistical Process Control effectively identified temporal variability and process instability throughout the harvesting operation, providing a comprehensive approach for monitoring soybean seed quality and supporting decision-making during mechanical harvesting.