• Pore Water Sampler Soil ColumnSpecialised research equipment specifically designed for soil columns
  • Simultaneous measurements of soil moisture and EC (salinity) with our high accuracy, low cost probes
  • Specialised tensiometers for soil water potential measurements
  • A large range of pore water samplers and nutrient analyzers
  • Complete range of data logging solutions

 

case studies and application notes

 

soil water content sensors for soil columns

The METER Group range of TEROS sensors are ideally suited for measuring soil water content for soil columns research.

The stainless steel needles are long and narrow, minimizing disturbance in the soil column profile. They can also be installed into intact profiles because of the robust and rugged design. The sensors output volumetric water content. Using the manufacturer’s calibration, the accuracy of the TEROS sensors is 3% or better. Accuracy can be improved with a custom calibration for specific soil types to less than 1% – read the details here and note various methods discussed in this paper.

The METER Group (formally known as Decagon Devices) range of sensors have been cited in over 345 peer reviewed publications on soil columns research. For example, a study used soil water content sensors in a soil column to study methane fluctuations simulating a landfill dynamic.

 

soil temperature and electrical conductivity (EC) sensors

Many soil column studies not only focus on soil temperature and EC dynamics. For example, a study in the journal Geoderma assessed “the relative importance of water vapour movement under moisture, temperature and osmotic gradients on moisture and energy budget in the presence of salts”.

The TEROS-11 sensor measures soil water content and temperature; whereas the TEROS-12 sensor simultaneously measures soil water content, temperature and EC. The use of these sensors can contribute to further insights into vadoze and edaphic processes studies in soil columns.

 

soil water potential: MPS-6 sensor or tensiometers?

The water potential, or suction, of soils is a critical parameter that is frequently measured in soil column studies. There are two sensors that are ideally suited to soil columns research: the MPS-6 (TEROS-21) Digital Matric Potential and Temperature Sensor; and the TEROS-32 Tensiometers.

The most significant difference between the sensor types is their measurement range. The MPS-6 has a measurement range between -9 and -10,000 kPa; whereas the TEROS-32 measurement range is between -85 to +50 kPa.

The MPS-6 is better suited to studies on drier soils; whereas the TEROS-32 is more suited to saturated soils or inundation studies.

Soil samples can also be taken to measure a wider range of soil water potential with the WP4-C Dewpoint Meter with measurement range between -0.1 and -300 MPa.

The MPS-6 soil suction sensor has been used in many soil columns studies. For example, researchers, publishing results in the Canadian Geotechnical Journal, deployed the MPS-6 sensor in 4m tall soil columns to measure water flow in unsaturated soils.

 

moisture release curves or water characteristic curves

It is possible to measure moisture release, or characteristic, curves on intact soil cores or miniature soil columns.

HYPROP 2 is a fully automated measuring and evaluation system based on Schindlers evaporation method (1980) to determine the hydraulic properties of soil samples.

With tensiometers in two depths the device measures the soil water tension as well as the unsaturated hydraulic conductivity. Additional the volumetric water content is calculated through a continuous recording of weight loss.

With these information the water retention curve can be illustrated.

 

microsensors & soil columns
Soil Columns and Capillary Fringe

Dynamics in the capillary fringe are difficult to measure in the field. Scientists and engineers, therefore, use soil columns in the lab to understand the capillary fringe. Image source: USGS.

Continuous measurements of biogeochemical parameters in the field can be extremely difficult. In order to understand biogeochemical process and patterns, scientists and engineers often resort to simulating field conditions in the laboratory via the soil column methodology.

Soil columns in the laboratory are extremely useful for understanding increased areas of biogeochemical activities such as the capillary fringe. The capillary fringe is the transition zone between the soil and the groundwater. As water levels rise and fall, the capillary zone can be highly dynamic. There are steep physical-chemical processes occurring within the capillary fringe as the zone fluctuates between oxic and anoxic conditions. Biological activity, in particular, can be high as groundwater increases and decreases. Greenhouse gases (GHG), such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), can fluctuate widely within the capillary fringe.

The AMT range of microsensors can measure several biogeochemical parameters including oxygen, pH, hydrogen sulfide, ozone, and hydrogen peroxide. These sensors can be installed at multiple depths within the soil column profile.