Solid fertiliser sampling and comparison of single tube triers of 12.7 mm and 19.1 mm opening widths

Solid fertilisers, from different locations in three blending plants, were sampled to determine the chemical analysis, size guide number (SGN), and uniformity index (UI) of raw ingredients and blends. Five different types of triers were used to sample fertilisers from five different locations, i.e., rail car, truck, bins, front-end-loader, stream sampling, and 10–10–10 bags. The fertiliser formulation 10–10–10 was sampled from bags using 12.7 and 19.1 mm width triers by a two-person team from the Pennsylvania Department of Agriculture. An innovative time-sequence procedure for sampling of bags was devised and implemented. Size analysis of ingredients from the three blend plants showed that there was a large deviation in SGNs and UIs, with appreciable variability from plant-to-plant. No substantial differences between SGNs and UIs for these two triers (19.1 mm and 12.7 mm width) were found, except for the 10–10–10 fertiliser (bags from the second quarter) from BP1 where all SGNs and UIs were within 7 and 2, respectively. Eleven out of the twelve samples from bagged fertilisers using 12.7 mm and 19.1 mm width triers had the same outcomes, i.e., only one sample from BP3 10–10–10 (bags from the third quarter) using had a conflicting outcome – the sample obtained using 19.1 mm width trier (SGN = 259, UI = 47) passed, whereas the sample with 12.7 mm width trier (SGN = 256, UI = 47) failed the chemical analysis test. Therefore, further study is needed to recommend the best trier to collect representative samples from fertiliser bags.