Controlled-release fertiliser

Controlled-release fertilisers are products whose dissolution is slowed by a physical barrier, chiefly the coating of soluble granules with films of polymer, resin, molten sulphur, gypsum or lacquer^[1]. The European regulation on fertilising products stipulates that products containing a polymer from category CMC 9 must state on the label the functional period, which must not exceed the interval between two recommended applications^[2]. These fertilisers differ from slow-release types, which rely on inherently low solubility or slow biological mineralisation, such as CDU, IBDU or oxamide^[3]. They also differ from nitrification inhibitors or urease inhibitors, which modulate enzymatic activity without forming a physical barrier^[4][5].