Bio-based coatings with tailored release property of coated NPK fertiliser

During the study, lignin-based polyurethane (LBP), rapeseed oil-based polyurethane (OBP), and their blend were successfully prepared and used as coating materials to regulate the nutrient release characteristics of NPK fertiliser. The physicochemical, barrier, morphological, as well as mechanical properties of the coating films, were systematically investigated and discussed. Furthermore, the water and soil release experiments were also performed to determine the release profile of the bio-based PU-coated fertilisers.

Sustainable measure

It was found that the amount of OBP in the OBP-LBP bio-blend was positively correlated to the longevity of the coated fertiliser. The addition of increasing amounts of OBP in the coating formulation could prolong the longevity of the coated fertiliser. The longevity of OBP coated granular NPK fertilizer reached a maximum value of 70 days for the complete release of nutrients. As the researchers point oit, the bio-based PU formulation through the modification of weight ratios of OBP and LBP can be considered as a sustainable measure to regulate the nutrient release characteristics and to produce a coated fertiliser with extended longevity and therefore enhanced efficiency.

The study has been published in Progress in Organic Coatings, Volume 170, September 2022.