Biochar is known as a well-developed porous carbonaceous material with multifunctional abilities that can enhance the physical properties of soils. However, the lack of certainty about the consequences of biochar application to soils has limited its acceptability. Application of biochar can lead to a series of changes in the physical functions of soil, which are crucial in both agricultural and environmental management. The type of feedstock, pyrolysis conditions, size of particles, and rate of amendments are responsible for biochar effectiveness. Concurrently, the physical characteristics of soil, such as particle-size distribution, can intensify the impacts. Beside the physical attributes, the chemical components and interactions between biochar and the soil interface may play an important role. The chemical properties, such as the value of electrical conductivity, pH and zeta potential, are the remarkable parameters in the hydrophysical behavior. The summary proposes that biochar has a great contribution In enhancing the definite range of aggregation formation, reduction of compaction and shear strength frequency and/or intensity, improvement of microorganisms activity, and abundance. Simultaneously, biochar plays a devastating role by filling the pores, blocking the water flow pathways, and inhibiting macro fauna growth. Particle size of biochar as a major factor, and surface functional groups as a minor factor, affect the performance of biochar in improving the hydrophysical properties of amended soils. The increment in the dosage of biochar application is not promising to enhance the physical properties of soils. Therefore, it is necessary to find a balance between the consumption of biochar and promotion of the soil-water dynamic. This review provides an overview of fastidious perspectives on how to achieve an efficient and sustainable use of biochar in hydrophysical properties.

Land-use change (LUC) and salinization interact synergistically to regulate depth-dependent fractionation and biological mediation of soil organic carbon (SOC) in vulnerable agroecosystems. Unlike previous syntheses addressing these drivers separately, the present review integrates them within a depth-resolved biological framework to reveal their combined effects on fraction-specific distribution under contrasting anthropogenic and ionic regimes. In the topsoil (0–30 cm), LUC and salinity synergistically collapse fungal networks, suppress carbon use efficiency, and restructure microbial communities to accelerate particulate organic matter (POM) turnover and impair mineral-associated organic matter (MAOM) formation. In the subsoil (>30 cm), salinity-driven clay dispersion and pore occlusion restrict oxygen diffusion and carbon accessibility, while LUC-induced loss of deep-rooting vegetation reduces carbon supply to mineral-associated pools. These depth-decoupled mechanisms render subsoil MAOM relatively resilient to direct ionic stress but highly vulnerable to land-use legacy, a distinction rarely represented in existing conceptual models. The evidence highlights key management implications, including restoring biological complexity in topsoil through reduced tillage, mycorrhizal re-establishment, and osmotic stress alleviation; conserving subsoil carbon by restoring deep-rooting vegetation and maintaining favorable ionic conditions for organo-mineral stabilization; and using depth-specific biomarkers, including enzymatic stoichiometry, fungal-to-bacterial ratios to detect SOC vulnerability before measurable losses occur. Future research should prioritize depth-explicit monitoring and integrated biological–physicochemical approaches to improve predictions of SOC dynamics. The resulting framework provides a mechanistic basis for depth-differentiated carbon management in salinizing landscapes.