Biodegradable all-cellulose composite hydrogel as eco-friendly and efficient coating material for slow-release MAP fertilizer

In the attempt to develop a novel coated fertilizer with combined slow release and water retention properties, all-cellulose hydrogel formulation was applied as waterborne and swellable coating material of monoammonium phosphate fertilizer (MAP). The biodegradable formulation was prepared from sodium carboxymethyl cellulose/hydroxyethyl cellulose blend filled with 5% of spherical regenerated cellulose particles ([email protected]). The coating process was performed in rotating pan and final coated products with two coating thicknesses and two crosslinking conditions were elaborated. A uniformly covered surface with increased crushing resistance up to 90.55 N and a positive impact on the soil water retention capacity were obtained after coating. Furthermore, the release experiment of phosphorus and nitrogen in water and soil media showed extended-release durations with maximal longevities of 12 h in water and 19–20 days in soil as compared to 1–2 h in water and 9–10 days in soil of uncoated MAP. The effect of the coating thickness and crosslinking condition on all investigated properties was taken into account. We assume in this work that cellulosic materials, being the main coating former of fertilizer, are capable to double the release time of MAP fertilizer with better preservation of the soil moisture.