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Wind erosion and dust emissions affect regions of the world with sparse vegetation cover or affected by agricultural practices that expose the soil surface to wind action. Research in this field has investigated the impact of soil moisture, land use, and land cover on soil susceptibility to wind erosion and dust emissions. The effect of soil salinity and sodicity, however, remains poorly appreciated. Salt accumulation in agricultural soils is a major concern in agroecosystems with high evaporative demand, shallow water tables or irrigated with water rich in dissolved solids. The understanding of how salts can affect aeolian processes in arid and hyper-arid landscapes remains incomplete. Recent studies focused on the effect of soil salinity on soil erodibility in dry atmospheric conditions, while the effect of soil sodicity and more humid conditions still needs to be investigated. Here we use wind tunnel tests to detect the effect of varying atmospheric humidity on wind erodibility and particulate matter emissions under saline and sodic conditions.Through a series of controlled wind tunnel experiments of soils treated with different concentrations of saline and sodic water, we find that the threshold velocity for wind erosion significantly increases with increasing soil salinity and sodicity, provided that the soil crust formed by soil salts is not disturbed. Indeed, with increasing soil salinity, the formation of a soil crust of increasing strength is observed, leading to an increase in the threshold wind velocity and a consequent decrease in particulate emissions. However, if the crust is destroyed by trampling, no significant changes in threshold velocity for wind erosion are found with increasing salinity and sodicity levels. Interestingly, after the threshold velocity was exceeded, soil crusts were readily ruptured by saltating sand grains resulting in comparable or sometimes even higher particulate matter emissions in saline and sodic soils compared to their untreated ('control') counterparts. Finally, understanding the role of atmospheric humidity under changing climate scenarios will help to modulate the wind erosion processes in saline-sodic soils and will help mitigate better dust emissions and soil management policies in arid and semi-arid climate zones. 

Soil salinization is an increasing global problem, especially in agricultural, coastal, and roadside environments. The increasing intensity of precipitation events due to climate change may be exacerbating these effects, such as through larger pulses of deicing salts entering roadside green stormwater infrastructure (GSI) and stronger coastal storms bringing seawater further inland. Although soils are often amended with biochar to remove pollutants and improve hydraulic properties, it may also mitigate the impact of salinity. Here, we compared the water retention properties and unsaturated hydraulic conductivities of both biochar-amended and unamended GSI soil media with varying salinity levels (1-25 dS m-1, using Na+ salts). The effects of salinity on both matric and osmotic potential included shifts in the plant-available water range, with the magnitude depending on the salt concentration and biochar content. Overall, biochar addition decreased the salinity and improved plant water availability in salt-affected soils. There was an increase in the integral water capacity (which describes the total amount of water the soil media can hold and release to a plant) for biochar-amended saline soils, demonstrating that biochar can reduce the total osmo-matric stress. On a macro scale, the high density of pores in biochar appears to increase soil hydraulic conductivity while reducing osmotic potential by adsorbing salt ions. On a micro scale, the negative surface charge of biochar likely counteracts the impact of the electric double layer of saline soils, reducing the total osmo-matric force on water molecules in soil solution. In effect, this helps the plant's osmotic potential to overcome the forces holding water molecules to soil grains. As soils become more saline due to ongoing climate-related snow events, biochar application might be an effective management technique for roadside and other saline soils. 

Abstract Arid and semiarid ecosystems around the world are often prone to both soil salinization and accelerated soil erosion by wind. Soil salinization, the accumulation of salts in the shallow portions of the soil profile, is known for its ability to decreases soil fertility and inhibit plant growth. However, the effect of salts on soil erodibility by wind and the associated dust emissions in the early stages of soil salinization (low salinity conditions) remains poorly understood. Here we use wind tunnel tests to detect the effects of soil salinity on the threshold velocity for wind erosion and dust production in dry soils with different textures treated with salt‐enriched water at different concentrations. We find that the threshold velocity for wind erosion increases with soil salinity. We explain this finding as the result of salt‐induced (physical) aggregation and soil crust formation, and the increasing strength of surface soil crust with increasing soil salinity, depending on soil texture. Even though saline soils showed resistance to wind erosion in the absence of abraders, the salt crusts were readily ruptured by saltating sand grains resulting in comparable or sometimes even higher particulate matter emissions compared to non‐saline soils. Interestingly, the salinity of the emitted dust is found to be significantly higher (5–10 times more) than that of the parent soil, suggesting that soil salts are preferentially emitted, and airborne dust is enriched of salts. 

Abstract Wind erosion and dust emissions affect regions of the world with sparse vegetation cover or affected by agricultural practices that expose the soil surface to wind action. Although several studies have investigated the impact of soil moisture, land use and land cover on soil susceptibility to wind erosion and dust emissions, the effect of surface soil salinity and sodicity on dust emissions, remains poorly understood. Salt accumulation in agricultural soils is a major concern in agroecosystems with high evaporative demand, shallow water tables or irrigated with water rich in dissolved solids. Recent studies have focused on the effect of soil salinity on soil erodibility in dry atmospheric conditions, while the effect of soil salinity and sodicity in more humid conditions still needs to be investigated. Here we use wind tunnel tests to study the effect of high atmospheric humidity on wind erodibility and particulate matter emissions under saline and sodic conditions. We find that the threshold velocity for wind erosion significantly increases with increasing soil salinity and sodicity, provided that the soil crust formed by soil salts is not disturbed. Indeed, with increasing soil salinity, the formation of a soil crust of increasing strength is observed, leading to an increase in the threshold wind velocity and a consequent decrease in particulate emissions. Interestingly, after the threshold velocity was exceeded, soil crusts were readily ruptured by saltating sand grains resulting in comparable or sometimes even higher particulate matter emissions in saline and sodic soils compared to their untreated (‘control’) counterparts which can be explained by salinity‐induced aggregation and sodicity‐driven clay dispersion effects. Lastly, understanding the role of atmospheric humidity under changing climate scenarios will help to modulate the wind erosion processes in saline‐sodic soils and will help mitigate better dust emissions and soil management policies in arid and semi‐arid climate zones.