Novel superabsorbent membranes consisting of polyvinyl alcohol (PVA), cellulose nanocrystals originated from Ziziphus spina-christi fibers, nanosilica, glutaraldehyde, and glycerin (G) were manufactured by compression moulding process. Ziziphus spina-christi fibers are a new source to isolate pure cellulose nanocrystals via mechanical and chemical treatment. Ziziphus spina-christi fibers were used to improve water-saving irrigation systems. Glycerin was used to increase the elasticity of superabsorbent membranes. These membranes were characterized by FTIR, XRD, SEM, mechanical testing, and thermal analysis. Superabsorbent membranes showed greater equilibrium swelling capacity compared with neat cross-linked PVA. Moreover, water transport mechanism of all superabsorbent membranes followed Fickian diffusion type. Superabsorbent membranes exhibited good pH-dependent swelling reversibility and high-water retention capacity, making it more efficient water-saving material. The superabsorbent membranes were also investigated for antimicrobial activities against pathogenic bacteria like Candida albicans (fungus), Bacillus subtilis (G+ve), Staphylococcus aureus (G+ve), Proteus vulgaris (G-ve), and Erwinia carotovora (G-ve). The results showed that design of innovative bioactive superabsorbent membranes is promising for the water reservoir, which might be most profitable in agricultural applications.