Siloxane and lauric acid copper dual modification improves hydrophobicity and elasticity of all biopolymer coated fertilizers with enhanced nitrogen release abilities

The preparation of biobased coated controlled-release fertilizers by bio-derived materials was crucial for green and sustainable development in agricultural production. Yet, considerable endeavors were still urgently needed to be devoted to improving the unwanted flaws of biobased materials, i.e. high hydrophilicity and abundant micro-pores. Herein, single- and dual-modified coated fertilizers were successfully developed based on all-biobased coating materials. The characteristics of the unmodified and modified coated fertilizers were also compared. The results indicated that the outermost layer modification by lauric acid copper improved the hydrophobicity and swelling capacity of the all-biobased membrane, prolonging nitrogen release period by 53 days. The water contact angle of dual modified fertilizer by siloxane and nano lauric acid cooper attained 105° and its swelling volume was relatively larger, which contributed to a longer nitrogen release longevity (112 days). Therefore, the dual modification showed more efficiency in improving the controlled-release ability and simultaneously simplified the preparation technology. Besides, compared to the single modification, this strategy decreased the nanomaterial dose and then lowered the potential environmental risk of long-term use of nanomaterial. The novel modification technique and dual-modified all biomembrane material could provide guidance for the future development of renewable and environmentally friendly coated fertilizers.