Kent Scientific Services, a public analyst laboratory, selected a Stuart STR4 rotator to meet the requirements of its fertiliser enforcement analysis work. The prescribed analysis methods for checking the nitrogen and phosphorus content in fertiliser samples require flasks to be mixed end-over-end at 35–40rpm, faster than many other rotators can achieve.Nitrogen, Phosphorus and Potassium
are the three primary nutrients needed in large quantities by plants. Manufactured fertilisers, used to supply crops with nutrients the soil lacks, have to be labelled with three figures indicating their NPK content. The regulations 1996 require the figures to be checked by standardised analysis techniques. Kent Scientific Services, one of 18 public analyst laboratories in England, provides scientific and calibration services for local authority enforcement agencies, including analysis of fertiliser samples collected by local Trading Standards officers from manufacturers’ premises or at the point of sale.