the problem with measuring humidity in compost is not so much the temperature but the variability of temperature and the high levels of potential contaminants (which will damage most thin film sensors)
I am not aware of any commercial system , but I found that hydrogels (the materials from which they make contact lenses) absorb water in direct proportion to RH. Once calibrated, the RH can be measured by burying a contact lense blank in the compost for a day or so then dig it up and weigh it .
The smaller the piece of hydrogel the faster it responds. They also swell in proportion to RH so attaching it to a pressure sensor or strain guage might yield a useful sensor.
Get in touch privately if you want to discuss this further
[EMAIL PROTECTED]
Denis SICAMOIS wrote:
Dear Bruce,
As manufacturers and suppliers of soil science equipment, customers often ask us equipment to measure humidity in compost. Is there anyone in the discussion group who has experience of this? As far as I know, the main problems in compost humidity measurement are: temperature (can be over 80�C), homogeneity of the substratum, its low density, and the density changes during the composting process.
Thank you in advance for your comments.
-- Cliff Hignett Soil Water Solutions 45a Ormond Avenue Daw Park South Australia 5041 61 (08) 8276 7706 [EMAIL PROTECTED] www.soilwater.com.au
