“…3,4 These materials must be completely degraded in soil, without releasing substances toxic to biota and humans, be compatible with fertilisers, and enable controlled release of the active ingredient. A number of researchers reported embedding fertilisers in carriers made from degradable materials such as starch with poly-L-lactide, 5 gluten and KCl, 6 polymer hydrogels based on polyvinyl alcohol, chitosan, and their blends cross-linked with glutaraldehyde, 7 acrylamide/itaconic acid, 8 chitosan, 9,10 and the use of degradable coatings for granular fertilisers (based on the core/shell principle), employing wax, polyurethane, polysulfone, polyacrylamide, lignin, cellulose and its derivatives, starch, 5,11 -13 etc. At the present time, the main obstacle to the wide use of slow-release fertilisers is their high cost. For instance, the cost of polymer-coated urea is four to eight times higher than the cost of the commercial urea formulation, 14 mainly because of the high cost of the coating.…”