Abstract: In order to solve the problem of nicosulfuron residue in corn field leading to drug injury in the next crop of sorghum, this study prepared DT2 solid bactericide by single factor optimization method, and combined indoor pot experiment with field experiment to add nicosulfuron and apply bactericide DT2 to soil. The repair effect of DT2 solid bactericide on the residual soil of nicosulfuron and its mitigation effect on sorghum were determined. The optimal conditions for solid fermentation of Aspergillus terreus DT2 were pH value 7, inoculation amount 10% and fermentation time 168 h. The effective viable bacteria count can still reach 3.3×10⁸cfu/g after storage at room temperature for 90 days. The results of the indoor pot experiment showed that when the weight of nicosulfuron in soil was 0.023 and 0.046 mg/kg, the inhibition rate of nicosulfuron on sorghum plant height decreased from 26.95% and 49.23% to 1.79% and 2.24% after 30 days of treatment with bacterial agent 6.25 and 12.5 g/kg, respectively. when the weight of nicosulfuron in soil was 0.094 mg/kg, the inhibition rate of nicosulfuron on sorghum plant height was reduced from 51.39% to 4.89% after adding 25 g/kg bactericide for 40 days. When the weight of nicosulfuron in soil was 0.046 mg/kg, adding bacterial agent 12.5 g/kg, 10 days after treatment, the residual rate of nicosulfuron in soil decreased by 56.42% when the weight of nicosulfuron in soil was 0.05 mg/kg, which was significantly different from the control. The mass of nicosulfuron in soil was 0 at 30 days after treatment. DT2 can improve the soil environment, enhance the activity of soil enzymes such as soil urease, alkaline phosphatase, catalase, and soil microbial diversity such as bacteria and fungi. After 40 days of application, nicosulfuron could not only alleviate the inhibition of chlorophyll, net photosynthetic rate and root activity of sorghum, but also promote the growth of sorghum plant height, root length and fresh weight. Field test results showed that the addition of DT2 solid inoculum can effectively reduce the damage of nicosulfuron residue on sorghum, increase the seedling emergence rate and yield, and reduce the disease rate and plant height inhibition rate. When the dosage of nicosulfuron in soil was 20, 30 and 40 g a.i/hm², adding 300, 450 and 600 kg/hm² of DT2 solid inoculum, respectively, could reduce the inhibition of nicosulfuron residue on sorghum to the level of no significant toxicity. In conclusion, Aspergillus terreus DT2 bactericide has a good remediation effect on nicosulfuron residues in soil and has potential application prospects.

Key words: maize and sorghum, Aspergillus terreus solid inoculum, nicosulfuron pollution, remediation effect