proudly sponsored by
|
archiving of SOWACS proudly sponsored by |
|
>On 26 Jul 98 at 5:06, owner-sowacs@aqua.ccwr.ac.za wrote: >> The categories I'm thinking of are: >> - neutron attenuation >> - tensiometery >> - heat dissipation >> - capacitance (TDR, FDR, Phase transmission) >> Am I leaving any category out? > >Why not change "tensiometery" to "potential"? You can then include >gypsum blocks, fibreglass blocks and psychrometers (if any are really >using them for irrigation scheduling). Also, rather than the term >"capacitance" perhaps "dielectric" better describes the various >techniques that purport to rely on this aspect of physics for >moisture content determination. > >>Brendan George Research Officer There is on the one hand soil water content measurements, on the other hand tension (or "suction", or "potential") measurements. Some measurement technics are use in both, but with different conception of sensors. I would say "tensiometer" for all kind of sensor permitting tension measurement, like "humidimeter" (from french word, humidimetre, but there is parhaps a better terminology in english) for all kind of sensor permitting soil water content measurement. So I would distinguish which variable is measured, and with which technology. For ex. Gypsum blocks are electrical resistance tensiometers, ... If you measure humidity in a porous block- with whatever technic you want (resistance, heat dissipation, capacitance, ...), and have the characteristic tension/humidity curve in this block, when you put this block in the soil, you measure the tension in the soil : the porous block equilibrates his tension with soil tension. When , on the contrary, the measurement are made directly in the soil -you introduce' probes (electrodes, ...) directly in the soil-, then you measure humidity. Sincerely Carole Isberie Dr. Carole ISBERIE, Agronomist Cemagref, Agricultural and Environmental Engineering Research Institute, Irrigation team, Le Tholonet, B.P. 31 13612 AIX-EN-PROVENCE CEDEX 1, FRANCE _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/ tel. : +33 (0)4 42 66 99 44 (direct) fax : +33 (0)4 42 66 88 65 e-mail : carole.isberie@cemagref.fr web Cemagref : http://www.cemagref.fr