Delocalization of Salt Solution in a Semiarid Farmland Topsoil
2018
Cassel, Florence | Sharma, Shankar
Salt buildup is a global phenomenon in semiarid soils that leads to land degradation and water quality deterioration. These problems can be alleviated through the quantification of salt leaching from topsoil horizons. Delocalization of solid-phase salts and solution-phase leaching was evaluated within the topsoil layers of a semiarid farmland by utilizing a non-invasive electromagnetic sensing and stochastic modeling approach. The horizontal and vertical conductivity signals were strongly correlated (r = 0.988, P < 0.05) and characterized by high precision and low errors (0.12–0.18). Electrical conductivity across the field was highly variable within the 0.6-m profile with nearly all surveyed locations exhibiting values greater than 2 dS m⁻¹. Around 86% of the salinity data in 0.3-m depth ranged from 2 to 8 dS m⁻¹, and 56% data within 0.3–0.6 m surpassed 8 dS m⁻¹. Spatial depletion in salinity within the 0.3-m depth plausibly resulted from salt delocalization. The salinity values generally exceeded plant tolerance threshold limits and indicated that most crops would be adversely affected unless management practices were aimed at removing salts past the topsoil horizons. The leaching fraction levels ranged from 5 to 40% across the topsoil layers, and indicated the need for salt removal practices for most crops. Overall, salt delocalization analysis can benefit agronomic decisions for irrigation and soil quality management. The approach can be applied worldwide in locating impaired soil zones that need salt reclamation for developing best management practices pertaining to site-specific crop selection and agricultural water budgeting.
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