Deep soil sensors

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Ton_vN
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Deep soil sensors

#1 Post by Ton_vN » 10 Feb 2018, 14:35

Have done an experiment with several soil sensors, and concluded that with SHT11 with a certain quality you can measure temperature and humidity to a certain depth underground: see https://www.vannwnhzn.nl/esp8266a5_humtemp01.html

Empirically proven that prolongued immersion of an SHT11-sensor is not fatal:
measurement of temperature continues, but after some time the value of measurement for humidity from >100% drops to nil.
The experiment under my house made me start thinking about measurement in my garden at depts of -10cm, -20cm, -50cm and -100cm.

Is it technically/functionally possible to interface 3 or 4 SHT11-sensors at 1 ESP/WEMOS? Howto?
Last edited by Ton_vN on 26 Feb 2020, 08:33, edited 2 times in total.

Ton_vN
Normal user
Posts: 300
Joined: 21 Oct 2016, 15:20
Location: Hengelo (Ov)/ NL
Contact:

Re: Deep soil sensors

#2 Post by Ton_vN » 21 Jan 2020, 10:43

Looking at the 'official' meteo-stations, conclude that temperature is of prime value, humidity less, especially in deeper soil.
But humidity is an interesting aspect for the top soil.

Therefore now planning for following setup with 1* ESP8266&ESPEasy:
- 5cm with 1* SHT11~SHT15 (encapsulated) for Temperature & Humidity
-10cm/ -20cm / -50cm/ -100cm with 4*DS18B20 (in stainless steel housing) for Temperature only

Looks like the best (= most accurate) configuration to be handled by stable release R147.

Considering experience mentioned in previous message must invent some additional protection (and/or draining) for the encapsulated SHT1X to prevent submersion:
drying the sensor is an effective, corrective remedy, but preventing any submersion is better.

Lessons-learned (October 1st, 2020) during setup & test [see the attached pictures]:
- take latest version of ESPEasy (= later than R147)
- assembly of the array in open air => with good adhesive, because otherwise later pulling the array from soil as one piece is not possible!
- alignment of the 4*DS18B20 + ESPEasy in open air before putting the array in soil => include the SHT15 in the alignment setup!
- application of the DS18B20-array further is without problem
- SHT15, even in capsule and in extra semi-protective housing, recently showed the clear signs of drowning [by telling continuous -4% for Humidity, not returning to normal values during better conditions]
Visual check is not showing excessive water/moisture on and around the protecting capsule of the SHT15.
Conclusion: capsule around SHT15 plus additional 'room' is insufficient for protection of humidity sensor => more protection needed
Soil-array with 4*DS18B20
Soil-array with 4*DS18B20
DS18B20_Setup.jpg (18.74 KiB) Viewed 3522 times
Soil-array_Top&JunctionBox
Soil-array_Top&JunctionBox
DS18B20_Topside.jpg (22.67 KiB) Viewed 3522 times
SHT15_UpperHolder; is plantpot with SHT15 at bottom, to be filled with soil.
SHT15_UpperHolder; is plantpot with SHT15 at bottom, to be filled with soil.
SHT15_Upperpart.jpg (25.92 KiB) Viewed 3522 times
SHT15_LowerSupport: is platpot with corks, creating 'room' under UpperHolder
SHT15_LowerSupport: is platpot with corks, creating 'room' under UpperHolder
SHT15_Lowerpart.jpg (19.82 KiB) Viewed 3522 times
SHT15_Combined+Filled with soil: ready to be put in soil
SHT15_Combined+Filled with soil: ready to be put in soil
SHT15_Combination_filled.jpg (24.02 KiB) Viewed 3522 times

Ton_vN
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Posts: 300
Joined: 21 Oct 2016, 15:20
Location: Hengelo (Ov)/ NL
Contact:

Re: Deep soil sensors

#3 Post by Ton_vN » 16 Mar 2022, 17:21

Further experience described here

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