Quantifying the Effect of Soil Moisture on the Aerobic Microbial Mineralization of Selected Pesticides in Different Soils

Abstract

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.

Global Biogeography and Quantitative Seasonal Dynamics of Gemmatimonadetes in Soil

“…Multivariate regression was attempted; however, the fit of the univariate models could not be improved by addition of the other parameters measured in this study (data not shown). Many microbial activities are known to increase with soil moisture (15,21,42); however, microbial community structure responses to moisture are less clear. Some studies have found shifts in soil microbial community composition under different moisture regimens (11,15), while others have reported no relationship with soil moisture changes (3,29).…”

Rhizoremediation – Plant Microbe Interactions in the Removal of Pollutants

“…that affect the microbial activity as well as diffusion of the chemicals in the soil. The effect of soil moisture on the aerobic microbial mineralization of the selected pesticides was quantified by Schroll et al, (2006). They found a linear relation between the soil moisture and relative pesticide mineralization.…”

Rhizoremediation of Contaminated Soils by Comparing Six Roots Species in Al-Wafra, State of Kuwait

“…Schroll et al [18], Alberty [19], Guillot et al [20], Mastronicolis et al [21], Singh et al [22] are responsible for changes in microbial diversity and for expanded numbers and metabolic activities of microorganisms in the rhizosphere microenvironment, this phenomenon called the rhizosphere effect [10,15,17,23]. Many studies have investigated the effects of soil moisture, temperature, aeration, pH, and organic matter content on the biodegradation of pesticides [11,24].…”