Remediation of heavily saline-sodic soil with flue gas desulfurization gypsum in Arid-Inland China.

Soil salinity is a major limiting factor for crop production in arid and semi-arid regions of northwest China. Flue gas desulfurization gypsum (FGDG) is valuable waste resource which can be used to improve saline soil. Monolith lysimeter leaching experiment was conducted with FGDG in heavily saline-sodic soil of northwest China. The four FGDG treatments with nine replicates for each treatment were applied when the FGDG rate was 0, 15, 30, and 60 t ha⁻¹, respectively. Undisturbed sodic-saline soil was carefully collected in the 40-cm deep soil column. The results indicated that improvement effect on the depth of 0-10 cm soil layer was the best when the rate of FGDG was 60 t ha⁻¹. It can reduce pH by 1.85, exchangeable sodium percentage (ESP) by 44%, and exchangeable Na⁺ by 7.37 cmol/kg in top soil layer. The values of the above soil parameters fell in the normal range due to FGDG treatment. At the same time, FGDG application reduced soil bulk density and increased saturated hydraulic conductivity. But from the maize growth, the emergence rate, plant height, shoot, and root weight were the best when the FGDG rate was 30 t ha⁻¹. The results also showed that the FGDG application increased soil electrical conductivity value. Therefore, it is quite necessary to move saline ions into the deep soil layer through leaching process. Although effect of FGDG treatment of 60 t ha⁻¹ on top soil was the best, considering the improvement effects of entire soil profile, we recommend that the optimum rate of FGDG was 30 t ha⁻¹. [ABSTRACT FROM AUTHOR]