100-kernel (100-k) weight (reported in grams) indicates larger kernel size as 100-k weights increase. Kernel size affects drying rates. As kernel size increases, the volume-to-surface area ratio becomes higher, and as the ratio gets higher, drying becomes slower. In addition, large uniform-sized kernels often enable higher flaking grit yields in dry milling. Kernel weights tend to be higher for specialty varieties of corn that have high amounts of horneous (hard) endosperm.
- Average U.S. Aggregate 100-k weight (36.07 g) was higher than 2016/2017 (35.26 g), 2015/2016 (34.73 g) and 5YA (35.37 g).
- Average 100-k weight for export (36.07 g) and harvest (36.07 g) were the same. However, in past years 2011/2012 through 2016/2017, average 100-k weights ranged from 0.06 to 2.05 g higher at export than at harvest. Since 100-k weight is based on 100 fully intact kernels, breakage or reduction in whole kernels occurring in transit may have self-selected out small kernels with low 100-k weights that might have been more prone to breakage.
- The export samples had a lower standard deviation (1.43 g) than the 2017 harvest samples (2.53 g). The 100-k weight standard deviation was also lower at export than at harvest for 2016/2017, 2015/2016 and 5YA, indicating greater uniformity at export than at harvest.
- The average 100-k weight for the Gulf ECA (37.45 g) was higher than the Pacific Northwest (31.12 g) and the Southern Rail (36.80 g) ECAs.
- In 2017/2018, 58.1% of the samples had 100-k weight of 36.5 g or higher, compared with 22% in both 2016/2017 and 2015/2016. Thus, a higher percentage of kernels were heavier than 36.5 g in 2017/2018 than in the previous two years.
- 100-k weight for contracts loaded as U.S. No. 2 o/b (36.31 g) was slightly higher than for contracts loaded as U.S. No. 3 o/b (36.13 g).