Abstract:Sulfadiazine, sulfadimethazine and fluorophenicol were taken as tested antibiotics, indoor batch experiments were conducted to study the effects of different biochar addition (0, 2.145 and 28.65 kg/m2) followed by 3 a field ageing on the adsorption and desorption of antibiotics in slope farmland of calcareous purple soil, meanwhile field plot (20 m long and 5 m wide) experiment was conducted to study antibiotic transport in slope (6?) farmland with 2.145 kg/m2 biochar surface application and the biochar permeable reactive wall (40 cm in width and 40 cm in depth, with biochar content of 28.65 kg/m2) at plot bottom. The results showed that biochar addition significantly enhanced the adsorption and immobilization of antibiotics in purple soil, the isothermal adsorption and desorption fitted well with Freundlich equation. Sulfadiazine and sulfadimethazine exhibited nonlinear adsorption with or without biochar addition, but biochar addition introduced a new nonlinear sorption mechanism for florfenicol with the lowest Kow. Biochar surface application prevented more effectively the vertical leaching of antibiotics into the deep soil, while biochar permeable reactive wall with a ditch-ridge top reduced more effectively antibiotic output loads in the surface runoff, among of which, the lowest reduction was found for florfenicol with the smallest n-octanol/water partition coefficient.