Determination of relative composition of samples collected with open head spiral grain sampling probe

Grain sampling probes, also called spears and triers, are used to collect samples from bulk grain at rest and are known to draw a higher proportion from the uppermost levels. Probes are used to collect samples that will be aggregated for representative sampling but are also useful tools in grain drying research and in monitoring quality and pest presence during storage, where it is important to know how fully the sample represents the corresponding grain bed. In this study, a method was proposed to prepare color-differentiated 15.2 cm layers of corn to make a column of known proportions. A spiral open headed grain sample spear, which fills from the bottom to the top, was used to sample a column of 19.8% moisture dry basis dent corn, and the count and proportional mass of samples drawn with the spear were determined and correlated to the sample volume of a common handheld moisture meter tester (Agratronix MT-16 Grain Moisture Tester). Sampling methods of vertical grain spear insertion and USDA-recommended 10° from vertical were compared, and the impact of sampling higher-moisture corn kernels (24.8% dry basis) and a shorter 76 cm column was also determined. It was found that vertical sampling with the spiral spear had higher uniformity between samples, less top layer skew, and included more grain from the bottom layer compared to the 10° from vertical sampling angle. It was also found that the top skew was much higher with the shorter 76 cm column compared to the 91 cm column, and sampling of 24.8% grain did not have any statistically significant differences to samples collected of 19.8% grain. Finally, an adjustment factor is presented to find the weighted proportion of sampled grains reflective of 15.2 cm thin layers in a 91 cm column for 19.8% and 24.8% MC dent corn.