Novel fabrication of biodegradable superabsorbent polymer from wheat stalk for water holding and sustained fertilizer...

Water-retaining agents have been shown to significantly improve the efficiency of irrigation water use in long-term agricultural activities, outperforming traditional irrigation methods. However, existing water-retaining agents still face challenges related to cost-effectiveness and degradability. To address these issues, we developed a superabsorbent material composed of wheat stalk (WS) and polyacrylic acid (PAA)-polyacrylamide (PAM), fabricated via versatile polymerization techniques. The integrated properties of the material, including water absorbency, water holding capacity, urea sustained-release behavior, and soil degradation, were thoroughly evaluated. The results indicated that WS/PAA-PAM exhibited a water absorption capacity of 273.54 g g^-1 in deionized water and 44.54 g g^-1 in saline solution, demonstrating excellent water retention properties. Kinetic studies revealed that water diffusion followed Fick diffusion, and the swelling process could be described by a first-order kinetic model. Notably, the material maintained high water absorption even after three cycles of re-swelling. Furthermore, WS/PAA-PAM effectively controlled the release of urea, minimizing fertilizer loss due to runoff, thereby promoting sustained nutrient delivery. These findings highlight the potential of WS/PAA-PAM as a cost-effective, biodegradable water and fertilizer management solution, offering a promising strategy for improving water and fertilizer utilization efficiency in future agricultural applications.