[Effects of pig manure and oxytetracycline on microbial number and activity in soils with different fertility levels].
An incubation test was conducted to study the effects of antibiotics oxytetracycline on the microbial number and activity in three soils varied with fertility level under the conditions with or without pig manure application. The soils were injected with six concentrations (0, 0.1, 1, 10, 100, and 1000 mg x kg(-1)) oxytetracycline, and incubated for 30 d at 25 degrees C. Soil samples were collected on the 1st, 4th, and 30th day of incubation to measure the bacterial number, respiratory activity, and enzyme activity. Under no pig manure application, oxytetracycline had little effects on the soil bacterial number and activity. The EC10 values of oxytetracycline based on a 10% decrement of bacterial number, respiratory activity, enzyme activity, and NO3(-)-N concentration in treatment without pig manure were 36-1000 mg x kg(-1), 20-1000 mg x kg(-1), and 4-1000 mg x kg(-1) for S1, S2 and S3, while those in treatment with pig manure application were 2-656 mg x kg(-1), 2-81 mg x kg(-1), and 1-42 mg x kg(-1) for S1, S2 and S3, respectively. Soil fertility level had obvious effects on the dose-response relations between oxytetracycline and soil microbial number and activity. The effects of oxytetracycline on soil microbial number and activity increased with increasing soil fertility level, and the effects on microbial number and respiratory activity were higher than those on enzyme activity and NO3(-)-N concentration. The effects of oxytetracycline on soil microbial number and activity were time-depending, being the greatest on the 4th day of incubation. Overall speaking, oxytetracycline could exert temporary inhibition on soil microbes.
Zhang
Ming-Kui
MK
Institute of Soil and Water Resource and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310029, China. mkzhang@zju.edu.cn
Liu
Zhao-Yun
ZY
D000818:Animals; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development*; D015169:Colony Count, Microbial; D017753:Ecosystem; D004784:Environmental Monitoring; D005308:Fertilizers; D008372:Manure / Q000032:analysis*; D010118:Oxytetracycline / Q000494:pharmacology*; D012988:Soil Microbiology; D013552:Swine
D005308:Fertilizers; D008372:Manure; D010118:Oxytetracycline