FTD or TDR soil water evaporation measurements

[Malcolm Hensley]

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Greetings to all subscribers,

Our research team is studying rainfall use efficiency in dryland
cropping in a semi-arid area of South Africa.  We are planning to make
the necessary measurements to construct soil water evaporation curves
using different types of surface mulch.  The range in clay content of
the surface soils is from around 18% to 45%.  The plan is to use FDR
or TDR probes placed at depths of 50 mm and 100 mm below the soil
surface.  The soils are low in salt.  It would be appreciated if
someone could help us with information regarding the relative
advantage and disadvantages of these two kind of probes for this task.

A relevant source of concern is the effect of lightning on the 
probes.  This region has frequent storms with much lightning during
the summer.  Colleagues in Natal have had a number FDR probes
destroyed by lightning.  Does anyone have a remedy?

Thanks in advance

Malcolm Hensley
Agricultural Research Council - Institute for Soil Climate & Water
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