Abstract:

With the rapid development of greenhouse agriculture in China，secondary salinization has become increasingly severe，significantly affecting crop growth and soil health. This study investigated the effects of combining biochar with Bacillus megaterium on the remediation of secondary salinized soil. Through pot experiments，the effects of biochar combined with Bacillus megaterium on soil physicochemical properties，nitrate content，and cucumber growth were investigated. The results showed that treatments incorporating biochar and Bacillus megaterium（BT1 and BT2）significantly（p<0.05）reduced soil electrical conductivity（EC）and nitrate content. Specifically，the EC value of the soil under BT2 treatment was 47.25% lower than that of the control（CK），and nitrate content also decreased significantly. Additionally，the application of biochar and Bacillus megaterium significantly improved soil enzyme activity and microbial abundance. Simultaneously，the treatment of applying biochar and Bacillus megaterium significantly increased cucumber plant height，stem thickness，above-ground dry and fresh weight，and root vitality. The treatment also significantly enhanced the activities of antioxidant enzymes in cucumber leaves and reduced the content of malondialdehyde（MDA）. These findings indicated that the synergistic effect of biochar and Bacillus megaterium is highly effective in the remediation of secondary salinized soil，providing theoretical support and technical guidance for sustainable soil management in greenhouse agriculture.

Key words: biochar, Bacillus megaterium, cucumber, secondary salinization, soil physicochemical properties