Preparation and performance of degradable slow-release fertilizer coating material by a new ionic crosslinked hydrogel material

Abstract

We report a hydrogel with 25 % polyacrylic acid by grafting and mixing starch with polyacrylic acid and urea. The novel ionic crosslinking strategy through iron ions enabled the high biodegradability of a novel slow-release fertilizer coating material. The ionic cross-linking improved the degree of polymerization of the material and formed a compact structured membrane material, which extended the period of nitrogen release to a sufficient extent. The membrane material obtained through ionic cross-linking exhibited a low thermal decomposition temperature and high thermal weight loss. Material displayed significant degradation with a weight loss of 71.11 % in a 60-day degradation experiment conducted in soil. This cross-linking approach provides a novel route for developing encapsulated slow-release fertilizers. It expands the application of natural polymers in the field of slow-release fertilizers.