Degradation characteristics of sulfadiazine on the rhizospheric soils

Using a special rhizobox,degradation dynamics of sulfadiazine in soil were investigated under the effect of maize rhizosphere. We refined the interface( 0 ~ 5 mm) of root-soil to 1 mm,and the concentration of sulfadiazine were set to 1 and 5 mg·kg-1,respectively. Samples were collected after20,40 and 60 days,respectively. Correlation analysis between the degradation rate of sulfadiazine and the content of four kinds of organic acids was carried out to obtain the key factors affecting sulfadiazine in the process of degradation of rhizosphere soil. This study showed that the degradation rate constant of sulfadiazine on planted soils was much higher than that of unplanted soils. The largest and most rapid loss of sulfadiazine in planted soils appeared at 3 mm from the root zone. The order of degradation rate was: near-rhizosphereroot compartmentfar-rhizosphere. The relationship between the degradation of sulfadiazine and the concentrations of organic acids showed that acetic acid and malic acid were the key factors which affected the degradation of sulfadiazine on rooT-soil interface.