Overview on progress in polysaccharides and aliphatic polyesters as coating of water-soluble fertilizers

Nitrogen, phosphorus, and potassium are the major nutrients solicited in the fertilization process, and their supply is highly useful to improve agricultural productivity. The conventional fertilizers suffer from low efficacy due to the fast release of nutrients. For that, the coating of granular fertilizer is considered as the best way to enhance their efficiency. Nowadays, biodegradable polymers are replacing synthetic polymers and avoiding the accumulation of nondegradable plastic residues in arable land. Since the coating of fertilizers by sulfur was criticized, many research studies investigated the use of polysaccharide such as cellulose, chitosan, carrageenan, lignin, and starch or aliphatic polyesters such as polylactide and polycaprolactone as coating matrix for granular fertilizer coating to delay or control the dissolution rate of nutrients. This review starts by apprising the readers about the environmental impact of conventional fertilizers (uncoated) and then an overview on the use of all those biopolymers and their combination for the coating agent mineral fertilizer. Furthermore, the present contribution provides an outline on different coating processes solicited in the field and the slow-release fertilizers criteria.