Development of Multifunctional Carboxymethyl Starch-Based Semi-IPN Hydrogels for Water and Fertilizer Management in Maize Cultivation under Different Water Deficit Conditions

Agricultural sustainability faces significant challenges from water scarcity, inefficient fertilizer use, and environmental pollution, all of which threaten food security and ecosystem health. Conventional fertilizers often fail to synchronize nutrient release with crop demand, leading to substantial losses through leaching and runoff, while drought stress exacerbates these inefficiencies by limiting nutrient uptake. Addressing these critical issues requires innovative materials capable of enhancing water retention, minimizing nutrient loss, and supporting crop productivity under adverse conditions. This study introduces a novel, cost-effective, and sustainable hydrogel-based nanocomposite fertilizer carboxymethyl starch-g-polyacrylic acid/PVA/K-MMT@Urea designed to tackle these agricultural challenges. Synthesized via a simple radical in situ copolymerization process, the composite exhibits exceptional water absorption capacities (392.87 ± 8.05 g/g in distilled water and 70.38 ± 4.26 g/g in 0.1 M NaCl solution) and integrates slow-release mechanisms for nitrogen and potassium. Incorporating 1% of the hydrogel into soil significantly improved its water-holding capacity, extending moisture availability during drought conditions. When applied to maize cultivation, the hydrogel improved key growth parameters including leaf number, chlorophyll content, stem diameter, fresh and dry biomass, and nutrient uptake under drought stress. This dual-action material, combining water conservation and slow nutrient release, demonstrates its potential as a transformative solution for improving crop yield and reducing environmental impacts in water-limited agriculture.