Exploring the Feasibility of Polysaccharide-Based Mulch Films with Controlled Ammonium and Phosphate Ions Release for Sustainable Agriculture

Bio-based polymers are a promising material with which to tackle the use of disposable and non-degradable plastics in agriculture, such as mulching films. However, their poor mechanical properties and the high cost of biomaterials have hindered their widespread application. Hence, in this study, we improved polysaccharide-based films and enriched them with plant nutrients to make them suitable for mulching and fertilizing. Films were produced combining sodium carboxymethyl cellulose (CMC), chitosan (CS), and sodium alginate (SA) at different weight ratios with glycerol and CaCl2 as a plasticizer and crosslinker, respectively, and enriched with ammonium phosphate monobasic (NH4H2PO4). A polysaccharide weight ratio of 1:1 generated a film with a more crosslinked structure and a lower expanded network than that featuring the 17:3 ratio, whereas CaCl2 increased the films’ water resistance, thermal stability, and strength characteristics, slowing the release rates of NH4+ and PO43−. Thus, composition and crosslinking proved crucial to obtaining promising films for soil mulching.