Design and development of guar gum based novel, superabsorbent and moisture retaining hydrogels for agricultural applications

•Synthesis of novel, EGDMA cross-linked guar gum superabsorbent hydrogels.•Characterization with FTIR, SEM, thermal and water absorption studies.•Biodegradation studies of the synthesized hydrogel and half-life period determination.•Effect of hydrogel on maximum water holding capacity (MWHC) of soil.•Effect on water retention capacity, density and porosity of soil. The novel hydrogels were synthesized by grafting guar gum with acrylic acid and cross-linking with ethylene glycol di methacrylic acid (EGDMA). The synthesis of hydrogel was confirmed by characterization through 13C NMR, FTIR spectroscopy, SEM micrography, thermo-gravimetric analysis and water absorption studies under different solutions. Synthesized hydrogel (GG-AA-EGDMA) was confirmed to be biodegradable with half-life period of 77 days through soil burial biodegradation studies. The effects of hydrogel treatment on soil were evaluated by studying various physico-chemical properties of soil like bulk density, porosity, water absorption and retention capacity etc. The hydrogel which could absorb up to 800 ml water per gram, after addition to soil, improved its porosity, moisture absorption and retention capacity significantly. Water holding capacity of water increased up to 54% of its original and porosity also increased up to 9% of its original. The synthesized hydrogel revealed tremendous potential as soil conditioning material for agricultural applications.