http://www.legislation.gov.uk/nisr/1991/540/schedule/2/part/II/crossheading/determination-of-molybdenumn2/paragraph/3.6/madeThe Fertilisers (Sampling and Analysis) Regulations (Northern Ireland) 1991Local GovernmentGovernment Printer for Northern Ireland2016-09-06AGRICULTURESCHEDULE 2METHODS OF ANALYSISPART II11.DETERMINATION OF MOLYBDENUMREAGENTS3.6Ammonium ferrous sulphate solution, 4 g per 100 ml.