Zehua Zhou1, Jim Wang1, and Jianjun Du2. (1) School of Plant, Environmental and Soil Sciences, Louisiana State University, 104 Sturgis Hall, Baton Rouge, LA 70803, (2) Dept. of Environmental Science and Engineering, Zhongkai University of Agriculture and Technology, Guangzhou, China
Tylosin is widely used in animal production by preventing and treating diseases as well as promoting animal growth. This has raised public concern over its release into environment. Soil adsorption is one of factors that may determine the fate of tylosin after it inters soil through manure application. The purpose of this study is to evaluate the effect of pH on tylosin adsorption by poultry litter-impacted soils. Three representative soils, Briley, Ruston, and Savannah, collected from Northern Louisiana were chosen for this study. Tylosin sorption was carried out by equilibrating soils with a series of 0.01 M CaCl2 containing different levels of tylosin at pH 4.5, 6.0 and 7.5. After 24 h equilibration, tylosin remaining in solution was determined using high pressure liquid chromatography (HPLC), and tylosin sorbed was calculated by difference. Results showed that tylosin sorption by three soils fit well with the Langmuir model (R2 > 0.98; P < 0.001). Tylosin sorption was the lowest at pH 4.5 across the three soils with sorption maximum ranging from 1619 to 1690 mg/kg. The highest tylosin sorption occurred at pH 6.0 for Ruston with maximum of 2285 mg/kg, followed by Savannah (1954 mg/kg soil) and Briley (1780 mg/kg). These results suggested that pH was an important factor controlling tylosin sorption in soil.
