Case A-17380/+/MA 1950 Method of Treating Water Containing Fertilisers The invention provides a method for preventing or reducing the blocking of holes or emitters or other components in a drip, trickle or mini sprinkler irrigation system through which irrigation water containing a fertiliser is applied which comprises adding to the irrigation water 0.1 to 100 ppm, based on the feed water, of at least one anionic compound having threshold properties towards alkaline earth metal salts, the anionic compound being a homo- or co-polymer of acrylic or methacrylic acid, a copolymer of maleic anhydride or an organophosphorus compound, or a water-soluble salt of such a compound.
