Baudin, Natasia (2019) The degredation of crop protection products in Brazilian soils. PhD thesis, University of Warwick.

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Abstract

Before crop protection products (CPPs) become commercially available, they are subject to rigorous testing according to strict regulatory guidelines, including investigating the fate of these compounds in soil. The global use of CPPs requires an understanding of their behaviour in a range of soils, including those from both temperate and tropical regions. Results from previous CPPs fate studies have shown significant differences in Brazilian soils compared to European and North American soils. This thesis investigates the differences in bio-physico-chemical and pesticide fate properties between contrasting Brazilian soils and a UK soil.

Changes in microbial community structure and metabolomics over time in a pesticide regulatory test incubation system across Brazilian soils relevant to pesticide regulatory requirements and one UK soil were assessed. Significantly richer metabolomics and more heterogeneous microbial communities were observed at the beginning of the incubations. No major differences between Brazilian and UK soil were found as long as they shared similar properties. Soil organic matter (OM) content, pH and cation exchange capacity (CEC) were the main factors shaping soil microbial communities and metabolomics.

The adsorption coefficient (Kd), desorption over time, using the new 3 Phase Assay method (3PA), and degradation properties of ametryn, clodinafop, fomesafen, thiabendazole and trifloxysulfuron were assessed in the predominant soils in Brazil, Latossolo, Argissolo, Gleissolo and Neossolo soils, which are also the main soils used for agriculture purposes. No major differences in pesticide fate between Brazilian and UK soils were observed. Adsorption and retention of pesticides to soil colloids were associated with soil sorbent properties such as soil OM, clay and expandable clay content, as well as CEC. It was more challenging to relate pesticide degradation properties to soil characteristics due to the combined effects of abiotic and biotic factors. The 3PA test gave an indication of the amount of pesticide which can be present in the soil solution, thus showing promise for the development of a new method for the assessment of pesticide bioavailability in soil.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	S Agriculture > S Agriculture (General) S Agriculture > SB Plant culture T Technology > TD Environmental technology. Sanitary engineering
Library of Congress Subject Headings (LCSH):	Pesticides -- Biodegradation -- Brazil, Pesticides -- Environmental aspects -- Brazil, Soil absorption and adsorption -- Brazil, Soils -- Pesticide content -- Brazil
Official Date:	September 2019
Dates:	Date Event September 2019 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	School of Life Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Marshall, Samantha ; Bending, G. D. (Gary D.) ; Garrod, Mark ; McKillican, Carrol ; Bramke, Irene ; Schäfer, Hendrik
Sponsors:	University of Warwick ; Syngenta Seeds Ltd.
Format of File:	pdf
Extent:	xix, 201 leaves : illustrations (some colour)
Language:	eng

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