Crop protection products (CPPs) are an essential component of modern agriculture, necessary to improve crop yield to feed the ever-increasing world population. Regulation and safety testing of CPPs entering the environment is mandatory to ensure that their use is not at the detriment of environmental or human health. Regulatory laboratory studies typically over-estimate the persistence of CPPs within the environment as they are not representative of environmental conditions. This study investigated the role of non-UV light on CPP degradation and the development of soil surface communities. The inclusion of non-UV light in laboratory studies impacted the degradation of fludioxonil and cinosulfuron, increasing and decreasing the rate of transformation relative to dark conditions, respectively. Further, the inclusion of light increased non-extractable residues (NER) formation in fludioxonil, paclobutrazol and benzovindiflupyr. In a field based degradation experiment, the availability of photosynthetically active radiation (PAR) increased the transformation of benzovindiflupyr relative to when PAR was restricted. Further, the formation of paclobutrazol and benzovindiflupyr NERs was increased when PAR was not restricted, and the proportion of CPP remaining at the soil surface (0-5 mm) was higher when PAR was restricted. Targeted amplicon sequencing (Illumina MiSeq) revealed that bacterial and phototrophic communities at the soil surface changed with time, and that communities formed when PAR was available were structurally distinct relative to communities when PAR was restricted. In a further experiment, analysis of bacterial and phototrophic communities under crops with differing canopy characteristics showed that distinct communities formed at the soil surface relative to bulk soil, and that phototrophic communities of bare soil and under low-density canopies were structurally distinct to those that formed under high-density canopies. This work has potential implications for regulatory CPP degradation studies, and furthers the understanding of soil surface community development in temperate environments.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:675367 |
| Date | January 2015 |
| Creators | Day, Mark C. J. |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/73961/ |
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