Abstract
Abstract This study compared the effects of two superabsorbent hydrogels (polyacrylamide (PAH) and a starch-acrylamide-kaolin composite (SAKH)) with those of conventional water-saving practices (mulching and drip irrigation) on the soil's hydraulic properties, the growth of plants, and the yield of grains and seeds of rice, wheat, and safflower under arid conditions in southern Kazakhstan. A field experiment was conducted in 2024 using a randomised complete block design with five treatments. Treatment effects were highly significant across all measured variables (p < 0.001). PAH (0.5%) produced the most significant improvements in soil hydraulic performance, increasing water retention by 23.6-23.8% and infiltration depth by 27%, compared to the control. It also resulted in the highest available water content (up to 18.13 mm) and significantly outperformed both mulching and drip irrigation. SAKH and drip irrigation showed intermediate effects, whereas mulching did not differ significantly from the control for most hydraulic parameters. Plant growth and yield responses were crop-specific, but the ranking of treatments remained consistent. Across all crops, PAH produced the largest yield increase (+10.25 units), followed by SAKH (+5.23), drip irrigation (+4.13) and mulching (+2.79). A multiple linear regression model incorporating soil water retention and infiltration depth explained 92% of the variation in yield (R2 = 0.92, p < 0.001), demonstrating that soil hydraulic properties strongly predict crop productivity. Overall, hydrogels, particularly PAH proved to be more effective than conventional water-saving practices at improving soil water availability and crop performance. This indicates their high potential for enhancing water use efficiency in arid agroecosystems.