Effects of Gypsum, Langbeinite, Elemental Sulfur, and Compost on Remediation of Saline-Sodic Soil Degraded By Well Pad Construction.

Arid region energy development often redistributes subsurface salts to topsoil after mechanical disturbance, posing difficulties in reclamation under conditions of low rainfall. Our objectives were to evaluate selected chemical amendments and municipal solid waste (MSW) compost for remediation of Na-affected soil under field conditions. Disturbed, saline-sodic soil was mixed with langbeinite (L), gypsum (G), elemental sulfur (S), and/or compost (C) in the following eight treatments: L, LC, G, GC, S, SC, C, and control. Soil was packed into 0.46 x 0.61 m2 wooden frames with mesh screen on the bottom, buried to be level with the surrounding soil surface, and exposed to environmental conditions for one year. Samples were taken every three months at depths of 0-3, 3-8, and 8-15 cm. Soils were extracted with pH 8.5 ammonium acetate and analyzed for Ca, Mg, K, and Na concentrations on an ICP-OES. Soils treated with L and LC consistently exhibited the lowest sodium adsorption ratio (SAR) for all 4 sampling events. Soils with G and GC treatments exhibited intermediate SAR’s. Treatments containing elemental sulfur were the least effective during the study period, often exhibiting SAR higher than the control. This study does not present strong evidence for the use of compost in improving chemical amendment dissolution or effectiveness in leaching Na. The general pattern of changes in SAR over time is representative of precipitation events, while the magnitude and timing of changes in SAR are a function of the efficiency of the treatment applied in leaching Na.