Evaluating the Potential of Modified Activated Carbon Waste in Improving the Growth of Maize Plants in Inland Saline-Alkali Soils

Activated carbon waste is produced during flue gas desulfurization and denitrification. Due to its acidic and porous structure, activated carbon waste is expected to play a role in improving the saline-alkali soil. However, the activated carbon waste contains excessive salt content, which would limit its agricultural utilization. In the study, the physicochemical properties and heavy metals risk were evaluated for the original (OACW) and HNO3 modified activated carbon waste (MACW). A soil incubation experiment with different application amounts of MACW (CK:0 g·kg-1, A5: 5 g kg-1, A10: 10 g·kg-1, A20: 20 g·kg-1) was carried out to assess its effects on the properties of saline-alkali soil and the growth of maize plants. The results showed that after modified by HNO3, the pore size of MACW was increased, while the EC was decreased significantly compared to that of the OACW. After the MACW were applied for 80 days, the average weight diameter of soil aggregates increased by 31.49% and 16.02% for the A10 and A20 treatment as compared to the control, respectively. The pH and salinity content were also significantly decreased when 20 g kg-1 MACW was applied. The plant height and biomass of maize increased by 10.3% and 52.9% when 20 g kg-1 MACW was applied as compared to the control. The PCA results indicated that an obvious separation between the control (CK) and treated samples (5 g kg-1, 10 g kg-1, 20 g kg-1 was detected, in which the greatest difference was exhibited between 20 g kg-1 MACW application and the control. The above results demonstrated that proper application of MACW in saline-alkali soil could effectively improve the properties of saline-alkali soil and the growth of maize plants