Foreign material is important because it has reduced feeding or processing value. It is also generally higher in moisture content than the corn, and therefore creates a potential for deterioration of corn quality during storage. Additionally, foreign material contributes to the spout-line (as mentioned in Broken Corn). It also has the potential to create more quality problems than broken corn, due to its higher moisture level.
Foreign material in the U.S. Aggregate samples averaged 0.1% in 2016, lower than 2015, 2014, and 5YA, which all had 0.2% foreign material. Combines, which are designed to remove most fine material, appear to be functioning very well, given the consistently low level of foreign material found across the years.
Variability, measured by standard deviation, among the U.S. Aggregate samples in 2016 (0.16%) was less than 2015 (0.27%), 2014 (0.19%), and 5YA (0.22%).
Foreign material in the 2016 samples ranged from 0.0 to 1.6%, compared to 2015 (0.0 to 4.5%) and 2014 (0.0 to 5.5%).
In the 2016 crop, 94.2% of the samples contained less than 0.5% foreign material, compared to 91% in 2015 and 95% in 2014.
All ECAs had average foreign material values of 0.1% or 0.2% in 2016, 2015, 2014, and 5YA.