Long-term saline water irrigation decreased soil organic carbon and inorganic carbon contents

The results showed that, compared with 1 g L-1 water irrigation, 8 g L-1 saline water irrigation significantly increased soil water and salt contents. Moreover, 8 g L-1 saline water irrigation significantly decreased SOC and SIC contents in the 0-20 cm soil layer (p < 0.05) and mainly decreased SOC content in >1 mm aggregates and wheat-derived SOC content in bulk soil. In comparison, 4 g L-1 saline water had no significant effect on soil water, soil salt, SOC, and SIC contents.

These results indicated that a high concentration of saline water irrigation is harmful for soil carbon sequestration, while a low concentration of saline water did not affect soil carbon sequestration. Thus, using no more than 4 g L-1 saline water irrigation for 14 years can maintain soil carbon storage in the water shortage areas.