Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/2007
Publication Date: 2/26/2008
Citation: Long, D.S., Engel, R.E., and Siemens, M.C. 2008. Measuring Grain Protein Concentration with In-line Near Infrared Reflectance Spectroscopy. Agron.J. 100:247-252.
Interpretive Summary: Grain quality sensors are now commercially available for measuring the protein concentration of cereal crops during actual harvest. This study was conducted to determine the measurement accuracy of a near infrared reflectance-type optical sensor when mounted to a clean grain filling auger of a combine harvester. The DSquared Development ProSpectra™ sensor was calibrated in the laboratory to 231 samples of soft white winter wheat. The sensor was then mounted to a stationary test stand where it could be presented to a moving grain stream. Continuous readings of grain protein were obtained for reference grain samples that varied in known protein concentration. The sensor explained up to 93% of the variability in grain protein and measurements were accurate to within 0.5%. High accuracy was also achieved when the sensor was mounted to a Case IH 1470 combine and used to measure grain protein of soft white winter wheat during actual harvest. These findings prove the technical feasibility of measuring and mapping grain protein sensing from the combine during actual harvest.
Technical Abstract: With the advent of near infrared spectroscopic sensors, growers have the opportunity to measure the protein concentration of grain within farm fields during machine harvest. A feasibility study was conducted to determine whether the protein content of grain could be measured directly with an in-line, near infrared reflectance spectrometer mounted on a combine’s clean grain filling auger. The DSquared Development ProSpectra' sensor was calibrated to numerous samples (n = 231) of soft white winter wheat (R^2 = 0.91, SEC = 0.31%). Initial testing, when the sensor was presented to a moving grain stream on a stationary test stand, showed in-line spectroscopic measurements and reference measurements to be highly correlated (R^2 = 0.93, SEP = 0.45%). In addition, high accuracy was achieved (R^2 = 0.91, SEP = 0.5%) for in-line measurements of protein concentration when the sensor was mounted on the grain bin filling auger of a Case IH 1470 combine during actual harvest. These results prove the technical feasibility of in-line sensing for continuous, rapid throughput analysis of large grain volumes and mapping applications in precision agriculture.