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Soil plays a pivotal role in enhancing global water and food security. Irrigation water constitutes more than 70% of the global water demand. The anticipated demographic increase and changing climate will impose more pressures on the global water and food systems. Therefore, and to achieve the target of "more crop per drop per area", water management plans must be based on more accurate quantitative and dynamic approaches. It is increasingly obvious that the unique aggregates structure of the soil medium regulates water and nutrient circulations, and consequently defines soil and water health, productivity, and water use efficiency. However, the soil aggregates structure is not currently well considered in the quantification of soil–water holding properties. The authors applied a thermodynamic and soil structure-based approach to quantify soil–water holding properties. Specifically, the paper aims at providing a methodology, based on the pedostructure concept, to quantify field capacity (FC), permanent wilting point (PWP), and plant available water (AW). Pedostructure is a representative aggregates unit of a soil horizon that describes the structural organization of the soil medium. Four types of soil were analyzed considering various soil texture and aggregates structure: loamy fine sand, silt loam, clay loam, and silty clay loam. The calculated values for FC and PWP, based on the proposed pedostructure method, were compared with the recommended values by the standard FAO method and soil suction method. Results showed good agreement between the calculated values of the two methods. The proposed pedostructure method introduces a shift in quantifying the plant available water from a texture-based estimation to a soil aggregates structure-based calculation. Such a shift will enable capturing the changes in soil aggregates structure due to agro-environmental practices and the associated impact of these changes on soil–water holding properties. [ABSTRACT FROM AUTHOR]

Abstract Wastewater reuse is a practice that has been gaining attention for the past few decades as the world's population rises and water resources become scarce. Wastewater application on soil can affect soil health, and the manner and extent to which this occurs depends heavily on soil type and water quality. This study compared the long-term (15+ years) effects and suitability of using secondary-level treated municipal wastewater and brackish groundwater for irrigation on the water holding capacity of a clayey, calcareous soil on a cotton farm near San Angelo, Texas. The soil-water holding properties were determined from the extracted hydrostructural parameters of the two characteristic curves: water retention curve and soil shrinkage curve based on the pedostructure concept. In the pedostructure concept, these hydrostructural parameters are characteristic properties of the soil aggregates structure and its thermodynamic interactions with water. Results indicate that use of secondary treated wastewater increased available water capacity in the top horizon (0–15 cm) and decreased the available water holding capacity of this particular soil in the sub-horizons (15–72 cm). The brackish groundwater irrigation resulted in no effect on available water capacity in the top horizon, but significantly decreased it in the sub-horizons as well. The rainfed soil was the healthiest soil in terms of water holding capacity, but rainfall conditions do not produce profitable cotton yields. Whereas, treated wastewater irrigated soil is producing the highest yields for the farmer. Thus, this treated wastewater source and irrigation system can serve as a suitable irrigation alternative to using brackish groundwater, enhancing the water resource sustainability of this region. Graphical abstract Graphical representation of field capacity, permanent wilting point, and available water capacity for each horizon such that: (a) Ap horizon = 0 to 15 cm, (b) A horizon = 15 to 30 cm, and (c) B horizon = 30 to 72 cm Unlabelled Image Highlights • Treated wastewater and brackish groundwater are both potential alternative irrigation sources. • Field capacity, permanent wilting point, and available water are indicators of a soil's health. • Treated wastewater and groundwater decreased the soil's water-holding ability in the lower horizons of this soil. • Treated wastewater not degrades soil properties any more than the groundwater and produces higher yields for the farmer. • Water conservation solutions should be specific and localized to each region. [ABSTRACT FROM AUTHOR]