Effects of biogas residues containing antibiotics on soil enzyme activity and lettuce growth

To investigate the effects of biogas residues containing antibiotics on lettuce growth and soil enzyme activity, the antibiotics oxytetracycline and sulfadiazine were used as additives; two kinds of feedstocks including pig manure and straw were chosen. Results showed that the higher the concentrations of the antibiotics are, the stronger the inhibition of soil sucrase activity becomes. The activity of sucrose enzyme in the test group with a single concentration of 60 mg/kg was significantly lower than the group that was treated with 0 mg/kg. In the mass, the organic fertilizer containing antibiotics can improve the soil urease activity and increase the urease activity of the soil. In the growth phase, urease activity increased by 27% from 0.85 mg NH₃-N/(g day) in the blank group to 1.08 NH₃-N/(g day) in the 0-mg test group. During all growing stages of lettuce, though the effects of the biogas residues containing oxytetracycline and sulfadiazine on the soil catalase activity were not obvious, the field application could inhibit the activity of soil catalase to some extent.