Slow-release fertilisers by biodegradable coating
In a recent study, biodegradable sodium alginate–lignin (SA-L) blend formulations at different SA/L ratios were developed as low-cost coating material for highly efficient slow-release di-ammonium phosphate (DAP) fertiliser.

The structural and chemical properties of different coating formulations were investigated via FTIR spectroscopy, and the slow-release capability of coated fertilisers was determined in water, as well as in soil. Moreover, their impact on the water-holding and retention capacities of soil was also examined. Experimental results indicated that the application of developed coatings corrected the fertilizer surface irregularities by forming a uniform and compact polymeric film. Further, they significantly enhanced its mechanical properties and extended the maximum nutrients availability toward longer periods.
New eco-friendly slow-release DAP fertiliser
It was also found that increasing the lignin content favorably affected the slow-release behavior, exceeding one month before the nutrients complete release in soil, instead of only four days obtained using uncoated DAP. Findings from this work indicated that SA-L blend coating material could interestingly serve in producing new eco-friendly slow-release DAP fertiliser with improved physical quality and nutrients use efficiency.
The study has been published in Journal of Coatings Technology and Research, Volume 19, September 2022.