Sodic Soil Reclamation Potential of Gypsum and Biocharadditions: Influence on Physicochemical Properties and Soil Respiration

Reclamation of sodic soils is proving increasingly vital as greater land area becomes salt-affected in the northern Great Plains of the United States. Flue gas desulfurization gypsum (FGDG) can be an agriculturally important resource for increasing land productivity through the amelioration of sodic soils. Biochar is also considered as an aid in reclaiming degraded soils. In this incubation study, two rates of FGDG (33.6 Mg ha(-1) and 66.2 Mg ha(-1)), two rates of biochar made from sugar beet (Beta vulgaris L.) pulp (16.8 Mg ha(-1)), and one rate of FGDG combined with one rate of biochar (33.6 Mg ha(-1) ea.) were applied to a sodic soil. Soil physicochemical properties, including cationic exchange, pH, electrical conductivity (ECe), sodium adsorption ratio (SAR(e)), total organic carbon (TOC), water retention, and soil respiration rate, were assessed during and at the end of the incubation period. Addition of FGDG to sodic soil increased ECe from 3.5 to 8.4 dS m(-1) and decreased SAR(e) from 16 to 9. Biochar addition to sodic soil increased TOC from 62.2 to 99.5 mu g g(-1) and increased soil respiration rate (mg C kg(-1) soil day(-1)) on every measurement period. When FGDG and biochar were both added to the sodic soil, TOC did not significantly improve; however, ECe increased from 3.5 to 7.7 dS m(-1), SAR(e) decreased from 16 to 9, and soil respiration rate increased for all measurements. The results confirm there is potential for FGDG and biochar to reclaim sodic soils alone, and applied in combination.