Formation and release of non-extractable 14C-Dicamba residues in soil under sterile and non-sterile regimes.
The role of native soil microorganisms in the formation and release of non-extractable (14)C-residues, previously treated with (14)C-Dicamba, was investigated to examine their significance to the longer-term environmental effects on non-extractable pesticide residues. A 90 d study compared the fate of Dicamba under sterile and non-sterile regimes. In addition, soils were aged for 30 d and repeatedly extracted with a 0.01 M CaCl(2) solution, to an extraction end point, to produce non-extractable residues. The extracted soil containing non-extractable residues was mixed with clean soil that had been freshly spiked with non-labeled Dicamba at 0.2 mg kg(-1) to increase the bulk volume of the soil and stimulate microbial activity. Sub-samples were then introduced into microcosms to compare the extent of microbially facilitated release and mineralisation with release rates in sterile microcosms. The results show that microorganisms play a significant role in the formation and release of non-extractable Dicamba residues. The release of (14)C-activity in sterile microcosms was linked to physical mixing of the extracted soil with field soil prior to the beginning of the incubations. The released (14)C-activity may be further mineralized, reincorporated into humus, or taken up by plants or other soil inhabiting biota.
Gevao
Bondi
B
Department of Environmental Science, Institute of Environmental and Natural Sciences, Lancaster University, Lancaster LA1 4YQ, UK.
Jones
Kevin C
KC
Semple
Kirk T
KT
D001673:Biodegradation, Environmental; D002250:Carbon Radioisotopes; D003996:Dicamba; D017753:Ecosystem; D006540:Herbicides; D010573:Pesticide Residues; D012988:Soil Microbiology; D012989:Soil Pollutants
D002250:Carbon Radioisotopes; D006540:Herbicides; D010573:Pesticide Residues; D012989:Soil Pollutants; D003996:Dicamba