Sustainable Date Palm Biomass Hydrogel Improves Soil Hydro-Physical Properties and Tomato Growth Under Arid...

Water scarcity, rapid soil moisture loss, and high evaporative demand severely limit vegetable production in arid regions such as Qatar. Sustainable soil amendments that enhance water retention and stabilize plant water status are therefore critical for improving productivity. This study evaluated a biodegradable hydrogel synthesized from date-palm leaf cellulose using a sodium alginate crosslinking method and assessed its effects on soil hydro-physical properties and tomato (Solanum lycopersicum L.) performance under arid conditions. A pot experiment was conducted under semi-controlled conditions using a single-factor randomized complete design with three hydrogel rates (0, 1, and 2% w/w) and three replications, with one plant per pot. All treatments received the same seasonal irrigation depth, scheduled when soil moisture declined to approximately 60-65% of field capacity. The hydrogel exhibited rapid hydration behavior, reaching equilibrium within 30-60 min with a swelling ratio of 5.659 g g^-1, corresponding to a water uptake of 465.9%, and SEM analysis revealed a porous internal structure favorable for water retention. At 1 and 2% application rates, hydrogel significantly reduced bulk density, increased total porosity and field capacity, and maintained higher soil moisture across irrigation cycles. Tomato plants grown in hydrogel-amended pots showed substantial gains in fresh biomass and root length, together with higher chlorophyll content, leaf nitrogen concentration, and relative water content. Water use efficiency improved significantly at 1% hydrogel, whereas the 2% rate showed a positive but non-significant trend. Overall, the results demonstrate that hydrogels derived from date-palm waste can enhance soil water retention, plant physiological status, and tomato productivity, offering a locally relevant strategy to improve agricultural resilience in arid environments.