|Lerch, Robert - Bob|
Submitted to: North American Agroforestry Conference
Publication Type: Abstract Only
Publication Acceptance Date: 5/15/2009
Publication Date: 6/1/2009
Citation: Lin, C., Goyne, K.W., Kremer, R.J., Lerch, R.N., Garrett, H.E. Rhizodegradation of Sulfamethazine and Their Associated Impacts on Soil Microbial Activities. In: Gold, M.A., Hall, M.M., editors. Agroforestry Comes of Age: Putting Science Into Practice. North American Agroforestry Conference, May 31-June 3, 2009, Columbia, Missouri. 2009 CDROM. Interpretive Summary:
Technical Abstract: The use of sulfamethazine (SF) and tetracycline (TC) to maintain animal health in swine, poultry, or cattle operations results in significant application of these veterinary pharmaceuticals to the landscape during grazing or manure disposal operations. Drinking water resources contaminated by these veterinary antibiotics have raised public health concerns in Southwestern Missouri and other regions of US. Recent studies have demonstrated the benefits of using multi-species vegetated buffers to reduce the transport of these antibiotics. However, their fate in vegetative buffers, and their impact on the rhizosphere microbial activities has not been well documented. A growth chamber study was conducted to investigate the rhizodegradation of 3H-sulfamethazine and 3H–tetracycline of five plant species. The relationship of degradation with soil enzyme activities in the rhizosphere was also investigated. Plant species included: 1) switchgrass, 2) eastern gammagrass, 3) orchardgrass, and 4) hybrid poplar. All plant treatments were grown in pots containing Mexico silt loam soil. Pots containing soil without plants were used as controls. Plants were grown to maturity (~3 months), and the rhizosphere soils were collected. Radio-labeled SF or TC were then applied to the rhizosphere soil and incubated in the dark for 100 days. Among the plant species, hybrid poplar showed the highest capability for promoting degradation of SF in the rhizosphere. The significantly higher SF degradation rates in poplar rhizosphere appeared to be associated with its greater soil enzymatic activities. When comparing enzyme activities between antibiotic treatments, fluorescein diacetate hydrolytic and glucosaminidase enzyme activities were significantly lower in TC treated soils than in SF treated soils. The Beta-glucosidase activities were similar between the two antibiotics treatments. The results of this work indicate that hybrid poplar incorporated into buffer designs could effectively mitigate the impact of these two antibiotics in the environment.