An Eco-Friendly Slow-Release Urea Fertilizer Based on Waste Mulberry Branches for Potential Agriculture and Horticulture Applications

Development of a compound fertilizer for agricultural and horticultural applications remains an important challenge in the field of biomass synthesis on account of its raw material source and biodegradability. In this work, an eco-friendly slow-release urea fertilizer (SRUF) employing mulberry branch-g-poly(acrylic acid-co-acrylamide) (MB/P(AA-co-AM)) superabsorbent was prepared. The MB/P(AA-co-AM) superabsorbent was blended with sodium alginate, urea, and CaCl2 solutions to accomplish this synthesis process. The synthesis conditions of the SRUF and its application performance were examined. The results showed that under the optimal synthesis conditions the water absorbency and water absorbency rate of the SRUF reached 420.0 g/g and 60.0 (g/g)/min in deionized water, respectively. The water retention of the SRUF was 7.2 wt % after 25 d. The urea release in deionized water and soil both exhibited a typical slow release behavior. A degradation rate of 32.0 wt % was attained for the SRUF while it was buried for 90 d in soil.