Stevens Hydra Probe II Series, Manual

Page: 19 / 63

Taxonomy. In this system, all of the worlds’ soils are broken into 12 orders based on climate,
topography, biology and soil chemistry. Table 3.2 lists the orders.
The Hydra Probe can accommodate all of the soil orders. Andisols, gelisols and histosols are
soil that may have soil moistures and properties that depart from the Hydra Probe’s built in
calibration curves. If the bulk density is extremely low giving the soil an effective porosity
greater than 0.5, the user will need a custom calibration If a custom calibration is required see
Section 2.3. If the Hydra Probe needs to be switched from the default Loam calibration setting,
see the RS-485 or SDI-12 command sections in the appendix.
Soil
Order Climate or Regime Soil Characteristics Hydra Probe
Calibration
Entisol Sandy Young Soil Stream Flood Plain Sand
Inceptisol Silty Young Soil Evidence of red color Sand or Silt
Vertisol Shrink/Swell Clay Homogenized, Cracks Loam or Clay
Histosol Wetland Soil Anoxic Reduced State Loam or Custom
Aridisol Desert Soil Higher pH Sand
Mollisol Grass land Soil Higher pH Loam or Silt
Spodosol Needle Leaf Forest Soil Low pH Loam or Silt
Alfisol Forest Soil Low pH Loam or Silt
Ultisol Old Forest Soil Low pH Loam
Oxisol Ancient Forest Soil Red, Oxidized Loam
Gelisol Soil With Permafrost Organic Rich Loam or Custom
Andisol Volcanic Ash Soil Low Density Loam or Custom
Table 3.2 The 12 Orders of Soil Taxonomy, Characteristics and Hydra Probe Calibration setting.
3.4 Installation of the Hydra Probe in Soil
3.4.1 Topography and Groundwater Hydrology
The land topography often dictates the soil hydrology. Depending on the users’ interest, the
placement of the Hydra Probe should represent what would be most useful. For example, a
watershed researcher may want to use the Hydra Probe to study a micro climate or small
hydrological anomaly. On the other hand, a farmer will want to take measurements in an area the
best represents the condition of the crops as a whole.
Other factors to consider would be tree canopy, slope, surface water bodies, and geology. Tree
canopy may affect the influx of precipitation/irrigation. Upper slopes may be better drained than
depressions. There may be a shallow water table near a creek or lake. Hill sides may have seeps
or springs.
19