Abstract
Water scarcity and increased drought frequency threaten irrigated cereal production across arid and semi-arid regions. Superabsorbent polymers (SAPs) can improve soil water retention and reduce non-productive losses, but field-scale effectiveness depends strongly on placement strategy and soil conditions [1–5]. This study evaluated a commercially available cross-linked polyacrylamide SAP applied locally using a slitter-based implement at two rates (30 and 60 kg ha⁻¹) and two placement depths (20 and 40 cm) under irrigated wheat (Triticum aestivum L., cultivar ‘Steklovidnaya-24’) in Eastern Kazakhstan (April–June 2025). A randomized complete block design with three replications was used (6 × 4 m plots). Soil moisture was measured by depth (0–5, 0–20, 20–40 cm) using the thermostat–weight (oven-drying) method; soil reaction (pH) was measured in a salt extract prepared by the TSINAO method using a calibrated pH meter; and grain yield was assessed by whole-plot harvest and converted to a hectare basis. Localized SAP placement redistributed water downward, with a 3.6–3.8 percentage-point reduction in the 0–20 cm layer and a 3.2–3.6 percentage-point increase in the 20–40 cm layer, resulting in an 8–11% increase in root-zone moisture reserves. The number of irrigations decreased from two to one, reducing seasonal irrigation from 1,800 to 900 m³ ha⁻¹, while crop growth indicators visibly improved relative to the control. Overall, 30 kg ha⁻¹ placed at 20 cm provided the most favorable balance between agronomic benefit and input intensity, consistent with broader evidence that targeted subsurface SAP placement can enhance irrigation water productivity.