rock salt mining(Rock salt mining is an underground mining process in which the salt is physically dug out of the ground in an operation involving drilling, blasting and crushing the rock. The major percentage of this output is used for winter road maintenance)
calibration of measuring equipment(The determination or rectification of, according to an accepted standard, the graduation of any instrument giving quantitative measurements)
potassium fertiliser(A chemical fertilizer containing potassium. Potassium (K) is required by all plant and animal life. Plants require potassium for photosynthesis, osmotic regulation and the activation of enzyme systems)