Opuntia Ficus Indica based green composites for NPK fertilizer controlled release produced by compression molding and fused deposition modeling

Excessive fertilization causes ecological problems due to leaching issues. To solve this problem and promote agriculture sustainability an innovative green composite for controlled release fertilizers was produced by adding NPK fertilizer flour to a biodegradable polymer with or without Opuntia Ficus Indica (OFI) particles. Six for- mulations were produced and employed for the fabrication of devices both for compression molding and fused deposition modeling (FDM). Both fillers displayed a good dispersion in the composites, excellent adhesion with the polymeric matrix and effectively acted as reinforcement. The decrease of NPK release rate (up to 30 days) was achieved using whole composites prepared. By appropriately selecting the dimension of the particles, the addition of OFI and the production technique, was possible to modulate the NPK release rate: FDM samples containing fine particles of OFI and NPK displayed the fastest release. Release data were fitted according to Peppas-Korsmeyer model to understand the release mechanism.