Due to continuous water leakage from the soil in arid and semi-arid regions, crops frequently experience water deficits and fertilizer deficiency. To address these challenges, a bio-based superabsorbent polymer (CMAKG-SAP) was synthesized in this study via graft copolymerization. Morphological and thermal analyses revealed that CMAKG-SAP possessed a three-dimensional polymeric network with a porous structure, uniform elemental distribution, and high thermal stability. The maximum water absorption capacity of CMAKG-SAP reached 497.32 g/g. The swelling and water absorption processes were primarily governed by chemical adsorption, and the material exhibited strong resistance to acidic and alkaline conditions (pH 4-11). After five absorption-desorption cycles, CMAKG-SAP retained 81.44 % of its initial water absorption capacity. Soil water-retention and stagnation tests demonstrated that CMAKG-SAP effectively improved soil water-holding capacity in arid and semi-arid soils, indicating significant potential for agricultural applications. Nitrogen release and biodegradation experiments further showed that the nitrogen release mechanism of CMAKG-SAP in soil followed non-Fickian diffusion, with controlled-release fertilizer properties and biodegradability. Compared with 100 % DI and 50 % DI, applying CMAKG-SAP at 50 % DI can improve the fruit quality. In conclusion, CMAKG-SAP demonstrates promising potential for promoting water-saving cultivation and sustainable agriculture in arid and semi-arid regions.