Urea Uptake and Water Retention Properties of Potassium Polyacrylate Hydrogel for Agricultural Applications

Global food security faces challenges due to resource scarcity and climate change, necessitating sustainable agricultural solutions. This study investigates the use of super-absorbent polymer (SAP) hydrogels to enhance water and fertilizer retention, improving productivity with Brassica rapa subsp. Chinensis (Japanese Pak Choy) cultivation. Hydrogels at concentrations of 0.25, 0.50, 1.0, and 2.0 wt % were tested, with higher concentrations demonstrating superior water absorption attributed to increased surface area and hydrogen bonding. Dry hydrogels absorbed more urea than swollen ones, owing to their greater swelling capacity. Optimal urea uptake occurred at lower concentrations, moderate temperatures, and pH levels between 6.5 and 7.5, as confirmed through Fourier transform infrared spectroscopy analysis. Furthermore, the waterholding capacity of soil improved significantly, with soils containing hydrogels retaining up to 230% water after 24 h. Seed germination studies revealed that higher hydrogel concentrations led to better germination rates and early cotyledonary development of Pak Choy seedlings. Additionally, soils with higher hydrogel content remained wet and moist for up to 7 days, unlike soils with little or no hydrogel. These results demonstrate that SAP hydrogels effectively enhance water retention, fertilizer uptake, and early plant growth, offering a sustainable approach to improving agricultural productivity and addressing global food security challenges.