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)
lime(Any of various mineral and industrial forms of calcium oxide differing chiefly in water content and percentage of constituent such as silica, alumina and iron)