Spatial variability in herbicide degradation rates and residues in soil

Phytotoxicity of five substituted urea herbicides 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron), 3-(p-chlorophenyl)-1,1-dimethylurea (monuron), 3-phenyl-1,1-dimethylurea (fenuron), 3-hexahydro-4,7-methanoindan-5-yl) −1,1-dimethylurea (norea), and 3-(m-trifluoromethylphenyl)-1,1-dimethylurea (fluometuron) at 0, 10, 100, and 1000 ppm were determined in factorial combination at four urea nitrogen levels of 0, 45, 450, and 900 ppm with three Aspergilli: A. niger, A. sydowi, and A. tamarii. Response interactions were apparent, with all three fungi most tolerant for fenuron and least for diuron. Apparent tolerance order of the three intermediates were: A. niger, norea > fluometuron > monuron; A. sydowi, fluometuron > monuron > norea; and A. tamarii, fluometuron > norea > monuron. Oat (Avena sativa L.) bioassay for residual herbicide toxicity indicated significant differences in herbicide degradation rates between these three fungi at 5, 10, and 20 ppm in Eufaula sand. Diuron was more rapidly degraded than monuron at these levels with fluometuron and norea somewhat intermediate. A. niger was most effective in degradation of these herbicides with A. tamarii greater than A. sydowi. High nitrogen levels in soil organic matter amendment generally favored increased rates of urea herbicide degradation.

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Spatial variability in14C-herbicide degradation in surface and subsurface soils

Pest Management Science ◽

10.1002/ps.1092 ◽

2005 ◽

Vol 61 (9) ◽

pp. 845-855 ◽

Cited By ~ 44

Author(s):

Marie-Paule Charnay ◽

Sébastien Tuis ◽

Yves Coquet ◽

Enrique Barriuso

Keyword(s):

Spatial Variability ◽

Herbicide Degradation

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In-Field Spatial Variability in the Degradation of the Phenyl-Urea Herbicide Isoproturon Is the Result of Interactions between Degradative Sphingomonas spp. and Soil pH

Applied and Environmental Microbiology ◽

10.1128/aem.69.2.827-834.2003 ◽

2003 ◽

Vol 69 (2) ◽

pp. 827-834 ◽

Cited By ~ 110

Author(s):

Gary D. Bending ◽

Suzanne D. Lincoln ◽

Sebastian R. Sørensen ◽

J. Alun W. Morgan ◽

Jens Aamand ◽

...

Keyword(s):

16S Rrna ◽

Spatial Variability ◽

Sequence Homology ◽

Degradation Rate ◽

Denaturing Gradient Gel Electrophoresis ◽

Most Probable Number ◽

16S Rrna Sequence ◽

Ph Optimum ◽

Probable Number ◽

Degradation Rates

ABSTRACT Substantial spatial variability in the degradation rate of the phenyl-urea herbicide isoproturon (IPU) [3-(4-isopropylphenyl)-1,1-dimethylurea] has been shown to occur within agricultural fields, with implications for the longevity of the compound in the soil, and its movement to ground- and surface water. The microbial mechanisms underlying such spatial variability in degradation rate were investigated at Deep Slade field in Warwickshire, United Kingdom. Most-probable-number analysis showed that rapid degradation of IPU was associated with proliferation of IPU-degrading organisms. Slow degradation of IPU was linked to either a delay in the proliferation of IPU-degrading organisms or apparent cometabolic degradation. Using enrichment techniques, an IPU-degrading bacterial culture (designated strain F35) was isolated from fast-degrading soil, and partial 16S rRNA sequencing placed it within the Sphingomonas group. Denaturing gradient gel electrophoresis (DGGE) of PCR-amplified bacterial community 16S rRNA revealed two bands that increased in intensity in soil during growth-linked metabolism of IPU, and sequencing of the excised bands showed high sequence homology to the Sphingomonas group. However, while F35 was not closely related to either DGGE band, one of the DGGE bands showed 100% partial 16S rRNA sequence homology to an IPU-degrading Sphingomonas sp. (strain SRS2) isolated from Deep Slade field in an earlier study. Experiments with strains SRS2 and F35 in soil and liquid culture showed that the isolates had a narrow pH optimum (7 to 7.5) for metabolism of IPU. The pH requirements of IPU-degrading strains of Sphingomonas spp. could largely account for the spatial variation of IPU degradation rates across the field.

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Degradation of atrazine and bromacil in two forestry waste products

Scientific Reports ◽

10.1038/s41598-021-83052-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Trevor K. James ◽

Hossein Ghanizadeh ◽

Kerry C. Harrington ◽

Nanthi S. Bolan

Keyword(s):

Organic Matter ◽

Organic Matter Content ◽

Matter Content ◽

Organic Media ◽

Organic Carbon Content ◽

Waste Products ◽

Herbicide Degradation ◽

Temperature Regimes ◽

Degradation Rates ◽

Subsequent Degradation

AbstractThe persistence and degradation of two common herbicides, atrazine and bromacil in two organic media, wood pulp and sawdust were compared with two soils. The hypothesis tested was that herbicide degradation will be faster in high organic matter media compared to soil. Degradation of two herbicides was carried out in four different temperature regimes and in sterilised media. The degradation half-life (t½) was determined under above-mentioned conditions then compared to degradation in soil. The degradation as quantified by t½ of the herbicides was generally longer in both organic media. Although microbial degradation was an important factor in the mineralisation of these herbicides, overall, the pH of the media had a more profound effect on the desorption and subsequent degradation rate than the organic carbon content. The results of this study revealed that the hypothesis was only partially correct as organic matter content per se did not strongly relate to degradation rates which were mainly governed by pH and microbial activity.

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The Influence of dairy manure on atrazine and 2,4-dichlorophenoxyacetic acid mineralization in pasture soils

Canadian Journal of Soil Science ◽

10.4141/cjss95-054 ◽

1995 ◽

Vol 75 (3) ◽

pp. 379-383 ◽

Cited By ~ 17

Author(s):

James A. Entry ◽

William H. Emmingham

Keyword(s):

Microbial Biomass ◽

Key Words ◽

Fungal Biomass ◽

Bacterial Biomass ◽

Dairy Manure ◽

Dichlorophenoxyacetic Acid ◽

Manure Application ◽

Herbicide Degradation ◽

Degradation Rates ◽

2,4 Dichlorophenoxyacetic Acid

The influence of manure application to pasture soils on bacterial and fungal biomass and the atrazine (2 chloro-4 [ethylamino]-6[isopropylamino]-s-triazine) and 2,4-D (2,4 dichlorophenoxyacetic acid) mineralization was assessed in microcosms using radiometric techniques. Additions of 5 tonnes manure ha−1 yr−1 were made to three pasture soils over 20 yr in western Oregon at a rate of 0.42 t ha−1 each month. No manure or fertilizer was added to control treatments. We found greater amounts of total fungal and bacterial biomass in soils that received added manure. There were no differences among active bacterial and fungal biomass between pasture soils that received manure application and pasture soils that received no manure. Greater amounts of atrazine and 2,4-D were mineralized when manure was applied than when soil received no manure or fertilizer. Greater amounts of atrazine and 2,4-D were mineralized in the spring than in summer, fall or winter. Results of this study indicate that the application of dairy manure to pasture soils will significantly increase herbicide degradation rates. Key words: Pasture soils, microbial biomass, manure application, atrazine, 2,4-D, herbicide mineralization

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Degradation rates of alachlor, atrazine and bentazone in the profiles of Polish Luvisols

International Agrophysics ◽

10.1515/intag-2016-0053 ◽

2017 ◽

Vol 31 (3) ◽

pp. 401-410 ◽

Cited By ~ 2

Author(s):

Tadeusz Paszko ◽

Paweł Muszyński

Keyword(s):

Organic Matter Content ◽

Principal Component ◽

Exponential Model ◽

Matter Content ◽

Herbicide Degradation ◽

Degradation Rates ◽

Maximum Water ◽

Positive Correlations ◽

Water Holding ◽

Oecd Guideline

AbstractThe degradation rates of three herbicides (alachlor, atrazine, and bentazone) were examined according to OECD Guideline 307 in three profiles of grey-brown podzolic soil (Luvisol) in a laboratory experiment. The aim of the experiment was to determine herbicide degradation parameters and their relationships with soil properties. Degradation processes were effectively described by a first-order model. However, in some cases, the best results were produced by bi-phasic kinetics (hockey-stick and bi-exponential model). The degradation rates of the tested herbicides at 25°C and 40% maximum water holding capacity, established based on half-life values in the Ap horizon, increased in the following order: atrazine (32.6-42.8 days) < bentazone (3.4-16.6 days < alachlor (4.4-5.7 days). The correlation analysis and the Principal Component Analysis revealed significant positive correlations between the herbicide degradation rates and the organic matter content of soils. The depth-dependent degradation factors obtained for topsoil and two subsoil horizons (1: 0.42: 0.11 – based on average values, and 1: 0.31: 0.12 – based on median values) reflect the degradation abilities of Polish Luvisols. The values noted are soil-specific; therefore, they can also be applied to other pesticides in Polish Luvisols.

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