Wind erodibility and particulate matter emissions from of salt-affected soils: The case of air dry soils

Authors: KATEI, GANESH - Temple University; RINALDO, TOBIA - University Of California Berkeley; Van Pelt, Robert - Scott; D'ODORICO, PAOLO - University Of California Berkeley; RAVI, SUJITH - Temple University

Submitted to: Journal of Geophysical Research Atmospheres
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/17/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary: As irrigation of agricultural crops using groundwater continues, many areas are experiencing increasingly saline groundwater from return flow to the aquifer and from rebound of subtending aquifers. These salts tend to accumulate on the soil surface and may affect the erodibility or dust emissivity of the surface. USDA-ARS and university personnel created soil trays using three agriculturally important soils from the Southern High Plains of Texas and treated them to create replicate trays of four levels of salinity. These trays were dried in an oven and allowed to cool and rest in room-temperature air at low relative humidities. The trays were subsequently run in a laboratory wind tunnel, the wind speed at which erosion began (threshold velocity) was recorded, the soil loss during the wind tunnel test was recorded, and the dust emissions were captured on a filter. It was found that salinity generally increased the threshold velocity at which wind erosion began, Salinity tended to make the soil slightly less erodible, and that the dust emissions from the saline soils had much greater salt contents indicating that salt is easily eroded from the soil crust.

Technical Abstract: Salt accumulation in agricultural soils is a major concern in many agroecosystems around the world, particularly in regions with high evaporative demand, shallow water tables or irrigated with water relatively rich in dissolved solids. It is unclear how salt can affect aeolian processes in arid and hyper-arid landscapes. In fact, while research in this field has explained the impact of soil moisture, surface roughness, fires, grazing, and agricultural techniques on soil susceptibility to wind erosion and dust emissions, the effect of salinity remains poorly understood. Here we use wind tunnel tests to detect the effect of soil salinity on the threshold velocity for wind erosion and dust production in air-dry soils 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 electrical conductivity. Even though saline soils showed resistance to wind erosion in the early stages, 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 (> than 5 times more) than that of the parent soil, suggesting that soil salts are preferentially emitted and found airborne in dust.