Localized hydrogel co-application improves water use efficiency and wheat (Triticum aestivum L.) yield in arid agroecosystems: A resource-optimized strategy

Arid and semi-arid regions, particularly in Central Asia, face escalating food security challenges due to climate change and chronic drought, demanding innovative soil moisture management strategies for staple crops such as wheat (Triticum aestivum L.). This study introduces and validates an innovative agro-technological system that moves beyond conventional, high-consumption superabsorbent polymer (hydrogel) use to establish a highly resource-efficient and sustainable approach for dryland wheat cultivation. A split-plot field experiment was conducted across three distinct agroclimatic zones in the Turkestan Region of Kazakhstan (Kazygurt, Sairam, and the extremely arid Arys district). Eight treatments were evaluated, focusing on varying hydrogel dosages and localized co-application with reduced phosphorus and potassium (P/K) fertilizers. A novel patented slit-cutting unit was employed for the precise subsurface placement of the hydrogel–fertilizer mixture at a depth of 20 cm. Complementary laboratory experiments provided the mechanistic foundation, evaluating water absorption, retention, and vertical redistribution in the 0–20 cm and 20–40 cm soil layers. The hydrogel mixture increased total soil water retention by 14.3 %, while enhancing subsoil (20–40 cm) moisture content by 9.0 percentage points, confirming its function as an in-situ water reservoir. Field results identified Treatment 5 (Localized 30 kg ha⁻¹ hydrogel + 50 % P/K) as the optimal configuration, producing stable and significant wheat yield increases of 23.32–27.05 % across all sites compared with the control. Importantly, this precision-based method achieved 50 % fertilizer savings and 57 % reduction in hydrogel use compared to conventional broadcast application, achieving both economic efficiency and ecological sustainability. Overall, the localized subsurface co-application system establishes a new benchmark for dryland agriculture, offering a climate-resilient, input-efficient, and scalable technological platform for enhancing water use efficiency and sustaining food production under water-limited conditions.