Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: March 26, 2009
Publication Date: March 26, 2009
Citation: Joseph, R., Reed, S.T. 2009. The Effects of Endosulfan on Microbial Respiration. American Chemical Society Abstracts. Technical Abstract: Endosulfan (6,7,8,9,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4-3-bensodioxathiepin-3-oxide) is an organochlorine compound commonly applied to agricultural crops as an insecticide. However, little is known about its effect on non-target soil microorganisms. The effects of endosulfan on soil respiration were investigated in a study designed to assess the fate and transport of endosulfan with and without a buffer strip. Moisture, temperature and net CO2 production were measured in a bean field where endosulfan had been applied. Beans were grown in 11.4 x 2.4 m2 field with a 2.0 slope emanating from the center. At the base of each slope were four 4.1 x 1.8 m plots. Half the plots were planted to switch grass and half were bare soil. Endosulfan was applied to bean area. The experimental design included two treatments, no endosulfan and endosulfan. Net CO2 production was measured weekly using an ADC LCA-4 analyzer. Campbell Scientific CS616 Water Content Reflectometers were used to measure average soil moisture content between the surface and 30-cm depth. Soil temperature was measured with Campbell CS107 temperature probes at 6 cm deep. Soil microbial analysis was also conducted from soil samples collected at 0.3 and 0.9 meters from the edge of bean field. The data from the studied treatments was compared to determine the effects of the pesticide on observed readings. Endosulfan applications to a bean field resulted in inconsistent short-lived increases in soil respiration above untreated plots. No apparent relationship between soil moisture or temperature with soil respiration was observed. No correlation was found between soil moisture and soil respiration even though soil moisture likely influenced soil respiration rate. Soil respiration from the bare soil no endosulfan plots was consistently lower than any other plots. A short-lived inhibitory effect on fungi was detected but bacteria counts significantly increased in response to endosulfan.