Hidden Canyon soil profiles

A number of soil moisture and soil moisture/temperature profiles are replicated throughout the Hidden Canyon site. They provide continuous measurement of soil moisture and soil temperature at three depths. Installation began in the fall of 2009.

Measurement start date: 11 November, 2009

Relevant links:


  • Record seasonal and interannual changes in soil moisture and temperature at three depths.
  • Provide soil moisture/temperature data to support the ecohydrology experiments at Hidden Canyon.
  • Measure differences in SM/ST in high and low stand density areas and high and low slope position
  • Measure differences in SM/ST in snowmelt treatment and control plots


![media/hc_profiles1_scaled.jpg?250|Installation of Campbell 616 sensors]

Soil moisture and temperature sensor profiles were installed at Hidden Canyon in October of 2009 and 2010. One square meter soil pits were excavated to a depth of 70-80 cm. Soil was excavated in layers, placed on tarps, and three sensors were inserted into the vertical face of the excavated pit horizontally and parallel to the surface of the soil. Sensors were inserted at 5 cm, 20 cm, and 60 cm depths and the layers of excavated soil were replaced in order, and compacted using foot pressure. Several types of sensors are in use, in separate profiles. Four sensor profiles (1d, 2d, 3d, 4d) measure both soil temperature and soil volumetric water content using Decagon EC-TM's (combination sensors. Four profiles (1,2,3,4) measure soil volumetric water content only using CS-616's or Campbell CS-615's sensors. Two sensor profiles (5 & 7) have both water content reflectometers (CS-616s) and thermistors (Campbell 107s) installed in the same pit. Sensors are multiplexed at three separate Campbell AM-16/32 multiplexers and are controlled and read by a Campbell CR23x datalogger (Forest1).

Multiplexer, datalogger, and sensor connections are documented in .

Decagon EC-TM's

These sensors are digital. They must be turned on, require a 50ms delay, and they then output three numbers in serial format --- Soil moisture, conductivity (always 0 for these particular sensors), and soil moisture. Serial data is read in through a COM port (Instruction P15 in EDLOG) on the datalogger. There have been some problems with these sensors failing at install and the data they give seems to have a small diurnal oscillation in soil moisture that we can't explain. We are unlikely to use them again.

Not working:

  • Profile 4d-60cm, Profile 3d-20cm, and Profile 1d-60cm were down from install (roughly) until being replaced on Sept 8th.

  • Profile 2d-60cm is reading too low (all readings are negative) but the shape of the response seems good. The consensus among the Decagon people is that this sensor is either in an airgap or near a rock and it needs to be excavated and reinstalled. --- Greg Maurer2010/08/11 12:10

Campbell CS-616's

These are working pretty well, even though none of them are new and some appear to have been in service for a long time. The period is read with instruction P138 (CS616 Water Content Reflectometer), and then converted to soil VWC with a polynomial fit (Instruction P55) on EDLOG dataloggers. They can also be read with instruction P27 (Period Average). They appear to give more reliable data (no diurnal soil moisture pattern) than the Decagons do.

Campbell CS-615's

A number of the sensors installed in the soil moisture profiles are CS-615's. This was discovered after they were installed. These sensors have different programming and calibration routines at the datalogger, and the datalogger program had to be written with multiple loops to accommodate the mix of 615's and 616's. They are read with Instruction P27, but the parameters are different, as are the calibration coefficients (in instruction P55) for converting to soil VWC.

CS-615 sensor locations:

  • Profile 1 - 5, 20, and 60cm
  • Profile 2 - 5cm and 20cm
  • Profile 3 - 60cm

Parameters for reading 615 sensors at the dataloggers

  • All 615's are configured with calibration coeffients for low EC soils (< 1.0 dS m^-1^). C0 = -0.187, C1 = 0.037, C2 = 0.335.

Unsolved Campbell sensor problems

  • All Campbell sensors in profiles 1 and 3 gave an intermittent error reading (6999) intermittently for several months after install. Wiring has been thoroughly checked, and the MUX seems to work OK with the Decagons. Mysteriously, around April 30th (day 120), this intermittent problem got MUCH less frequent and the sensors gave mostly good data. We're not sure what changed. Data recorded between the intermittent errors (which was very sparse up until the end of April) is in the expected range for the sensors. --- Greg Maurer 2010/08/11 12:04

  • There is one sensor, Profile 3 - 20cm, that is reading too high, though the shape of the response seems to be normal, but reversed. Check this one's wiring. --- Greg Maurer 2010/08/11 12:10

Sentek Envirosmart Probes

In summer of 2010 several Sentek Envirosmart Probes will be installed. More to come on this later.


  • Profiles 1, 1d, 3, & 3d are multiplexed at Mux 1, a Campbell AM16/32 downhill of the forest tower.
  • Profiles 2, 2d, 4, & 4d are multiplexed at Mux 2, a Campbell AM16/32B uphill of the forest tower.
  • Profiles 5 and 7 are multiplexed at Mux 3, a Campbell AM 16/32 at about 48E and 25N.
  • More on wiring and programming for these instruments is in and on the Hidden Canyon datalogger page.

2010 Soil profile log

  • CS-615 sensors in Profile 2 began working as of 14 Jan, 2010 (New EDLOG program)--- Greg Maurer 2010/01/15 11:03
  • Decagon sensors in Profile 4d-60cm, Profile 3d-20cm, Profile 1d-60cm are not working. Tested these three sensors with a direct connection to a datalogger at the sensor leads and they all appear to be dead (-INF signal in Loggernet). --- Greg Maurer 2010/02/19 08:15
  • Three malfunctioning sensors (4d-60, 3d-20, 1d-60) were replaced Sept 8, 2010. They appear to work.
  • Renumbered site plots and profiles. Plots are 1-6 in order from east to west, profiles are sequential starting downslope in plot 1 (Profile 1), upslope plot 1 (Profile 2), downslope plot 2 (Profile 3), etc... See the experimental design pagefor more details on this.
  • Installed new profiles, numbers 5 and 7, in early October. These have Campbell CS-616s and 107 thermistors at each depth.
  • Rewired and reordered sensors at Mux 1 and 2, installed Mux 3 and wired profiles 5 and 7 to it. Forest 1 datalogger was down from Oct 8th to the 15th.
  • Installed new Forest1 datalogger program (v4) and the new Forest1 measurement scheme became operational at ~2:30pm Oct 16th.
  • Possible loss of data starting around Nov 11, 2010 to Jan 11, 2011. FIXME

Maintenance and data log

See here