Multi-Scale Soil Salinization Dynamics From Global to Pore Scale: A Review

Soil salinization refers to the accumulation of water-soluble salts in the upper part of the soil profile. Excessive levels of soil salinity affects crop production, soil health, and ecosystem functioning. This phenomenon threatens agriculture, food security, soil stability, and fertility leading to land degradation and loss of essential soil ecosystem services that are fundamental to sustaining life. In this review, we synthesize recent advances in soil salinization at various spatial and temporal scales, ranging from global to core, pore, and molecular scales, offering new insights and presenting our perspective on potential future research directions to address key challenges and open questions related to soil salinization. Globally, we identify significant challenges in understanding soil salinity, which are (a) the considerable uncertainty in estimating the total area of salt-affected soils, (b) geographical bias in ground-based measurements of soil salinity, and (c) lack of information and data detailing secondary salinization processes, both in dry- and wetlands, particularly concerning responses to climate change. At the core scale, the impact of salt precipitation with evolving porous structure on the evaporative fluxes from porous media is not fully understood. This knowledge is crucial for accurately predicting soil water loss due to evaporation. Additionally, the effects of transport properties of porous media, such as mixed wettability conditions, on the saline water evaporation and the resulting salt precipitation patterns remain unclear. Furthermore, effective continuum equations must be developed to accurately represent experimental data and pore-scale numerical simulations. Soil salinization refers to the excess accumulation of salt in soil to a level that affects crop production and ecosystem functioning. This poses existential threat to sustainable agriculture, food security, and soil fertility. Soil salinization is considered as one of the major drivers for desertification, resulting in a persistent loss of ecosystem services. It also imposes nutritious imbalances in plants that may induce significant alterations in Earth's organisms, ecosystems, and biodiversity. We synthesized recent advances on soil salinization at different length and time scales, ranging from pore to global scale, offering new insights, and presenting future perspective on the key challenges and open questions on soil salinization. Soil salinization poses existential threat to sustainable agriculture, food security, and soil fertility We synthesized recent advances on soil salinization at different length scales, ranging from pore to global scale We offer new insights and present future outlook on the key challenges and open questions related to soil salinization