On‐Combine Sensing and Mapping of Wheat Protein Concentration

Site‐specific measurements of grain protein concentration, in addition to grain yield, are potentially useful for assessing spatial variability in cereal crop production as needed in precision agriculture. This study investigated an on‐combine spectroscopic sensor for mapping grain protein levels within farm fields. The optical, near‐infrared sensor was calibrated in the laboratory to test samples of hard red spring wheat (r 2 = 0.99, SEC = 0.081%). Grain protein data for spring wheat were then acquired for a 45‐acre dryland wheat field, and compared with test samples that had been manually sampled from the combine's exit auger. The ability of the sensor to predict protein values declined in the field (r 2 = 0.55, SEP = 0.66%). However, a map of grain protein concentration derived from on‐combine sensing was highly correlated with a test map of grain protein (r = 0.93). The results are sufficiently promising to suggest that on‐combine spectroscopic sensing of grain protein concentration for mapping purposes is technically feasible.