Quantifying the effect of soil moisture on the aerobic microbial mineralization of selected pesticides in different soils.
A standardized quantitative approach was developed to reliably elucidate the effect of increasing soil moisture on pesticide mineralization. The mineralization of three aerobically degradable and chemically different 14C-labeled pesticides (isoproturon, benazolin-ethyl, and glyphosate) was studied under controlled conditions in the laboratory at an identical soil density of 1.3 g cm(-3). The agricultural soils used are characterized by (i) large variations in soil texture (sand content 4-88%) and organic matter content (0.97-2.70% org. C), (ii) fairly diverse soil-water retention curves, and (iii) differing pH values. We quantified the effect of soil moisture on mineralization of pesticides and found that (i) at soil water potential < or = -20 MPa minimal pesticide mineralization occurred; (ii) a linear correlation (P < 0.0001) exists between increasing soil moisture (within a soil water potential range of -20 and -0.015 MPa), and increased relative pesticide mineralization; (iii) optimum pesticide mineralization was obtained at a soil water potential of -0.015 MPa, and (iv) when soil moisture approximated water holding capacity, pesticide mineralization was considerably reduced. As both selected pesticides and soils varied to a large degree, we propose that the correlation observed in this study may be also valid in the case of aerobic degradation of other native and artificial organic compounds in soils.
Schroll
Reiner
R
GSF-National Research Center for Environment and Health Institute of Soil Ecology, Ingolstädter Landstrasse 1, D-85764 Neuherberg, Germany. schroll@gsf.de
Becher
Hans Heinrich
HH
Dörfler
Ulrike
U
Gayler
Sebastian
S
Grundmann
Sabine
S
Hartmann
Hans Peter
HP
Ruoss
Jürgen
J
D000332:Aerobiosis; D001673:Biodegradation, Environmental; D006813:Humidity; D008903:Minerals / Q000378:metabolism*; D009930:Organic Chemicals / Q000378:metabolism; D010575:Pesticides / Q000378:metabolism*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis* / Q000378:metabolism*; D014867:Water / Q000032:analysis / Q000737:chemistry
D008903:Minerals; D009930:Organic Chemicals; D010575:Pesticides; D012989:Soil Pollutants; D014867:Water