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Title: The degredation of crop protection products in Brazilian soils
Author: Baudin, Natasia
ISNI:       0000 0004 9358 2889
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2019
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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.
Supervisor: Not available Sponsor: University of Warwick ; Syngenta Seeds Ltd
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: S Agriculture (General) ; SB Plant culture ; TD Environmental technology. Sanitary engineering