Critical zone agrohydrology: An integrative paradigm for agricultural water sustainability

Meeting rising food demand under intensifying climate variability, soil degradation, and groundwater decline requires agriculture to produce more with less freshwater. We advance Critical Zone Agrohydrology (CZA) as a unifying framework that treats agricultural landscapes as human-managed critical zones—coupled systems extending from canopy to bedrock and operating from seasons to decades. CZA is organized around the Four Deeps (deep time, deep depth, deep coupling, and deep practice) and operationalized through a 5M cycle of Measuring, Mapping, Monitoring, Modeling, and Managing. This perspective expands conventional agrohydrology by accounting for long-term soil change, subsurface storage and flow, biogeochemical feedbacks, and human decision-making, thereby linking field efficiency with basin sufficiency. We illustrate implications for multifunctional soil management, nutrient-loss control, salinity rehabilitation, drought resilience, managed aquifer recharge, and cross-scale governance. By reframing agriculture as a potential contributor to aquifer stability, water quality, carbon storage, biodiversity, and durable productivity, CZA offers a practical pathway toward more resilient and basin-aware agricultural water management.