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  • 2017RobertHardyphd

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Out of the darkness and into the light: the quest for fluorescence-based soil tracers

Research output: ThesisDoctoral Thesis

Publication date2016
Number of pages205
Awarding Institution
  • Lancaster University
<mark>Original language</mark>English


This thesis explores the use of fluorescent tracers to monitor the redistribution of soil at high
temporal and spatial resolutions. Soil redistribution happens on a second by second basis
with individual particles moving millimetres at a time. There are few, if any, existing tracing
methods which permit the monitoring of soil movements at temporal and spatial scales that
are commensurate with the scales at which these movements happen. This thesis charts the
development of new tracing technologies that allow for the movement of soil to be
monitored at high spatial and temporal resolution, resolutions which are commensurate with
the movement of individual particles. This will allow for deeper insight into how soil moves
and has a range of applications for fundamental soil movement studies to applied agricultural
investigations. In order to study the movement of clay a novel fluorescent clay tracer was
created along with fluorescent imaging techniques which allowed for the movement of this
tracer to be captured. The movement of larger soil particles is also important and by using a
commercially available fluorescent tracer combined with fluorescent videography it was
possible to track the movement of individual soil particles across a soil surface during a
simulated rainfall event. The movement of these particles was captured 50 times a second
with sub-mm precision. A similar system was then developed for use in the field environment
and was demonstrated at field scale by monitoring the redistribution of a tracer across a soil
surface as a result of tillage. It was also possible to monitor the vertical redistribution of the
tracer within the soil profile by digging soil pits. The methods detailed here show that it is
possible to gain much information about the redistribution (i.e. change in location) of soil
across a soil surface without the inconvenience, expense and system perturbation that is
caused by traditional sampling. Overall these methods demonstrate that it is possible for soil
tracing to operate in a data rich environment providing new opportunities to develop,
parameterise and evaluate soil movement models.