Improving wheat quality consistency by density segregation

The end-use quality of grain crops can vary significantly within a given field. Research was conducted in northeastern Oregon to determine the amount of wheat quality variability due to landscape position and if improvements in the consistency of wheat quality delivered at the farm gate could be made by segregating wheat by landscape position and/or kernel density. The study was conducted on soft white winter wheat collected from fields representing three different cropping systems including annual cropped no-till, chemical fallow no-till and conventionally tilled summer fallow. Samples were taken from four areas in each field representative of the hilltops, north facing slope, bottom and south facing slopes and replicated three times. A portion from each sample was combined to form an additional sample representative of the grain collected from the entire field. The combined sample was separated into four density fractions using a gravity table. Grain from each sample location, representing the entire field and the four density fractions were analyzed for wheat quality factors including federal grade and a grain quality score based on test weight and kernel protein content. Federal grade and grain quality score were found to vary significantly across the field in all cropping systems. Grain from various landscape positions differed significantly in federal grade and grain quality score as compared to the control sample. Kernel density was also effective at segregating grain by quality with high and low density fractions having significantly better and lower quality respectively than the control sample. Sorting grain by density was superior to sorting grain by landscape position not only in the magnitude of separation obtained, but also in reducing the amount of quality variation within a sample.