Uncalibrated soil moisture values for relative data interpretation

Interpreting soil moisture data, like VWC% (volumetric water content), is contingent on many factors like soil type and texture, organic matter, and bulk density. Soil texture is a key variable which must be known to select a good calibration. But what happens when you don’t know your soil type, have large variations within a field and want to compare data, or want to compare different solutions?

Written by Merijn van Logtestijn on May 18 2023.

We built an algorithm to derive relative soil moisture values, also known as uncalibrated data, which provides insight into the behavior of soil moisture without needing to set a specific soil type (calibration).

Relative values with uncalibrated data

The uncalibrated data feature has been created for two types of users: users who want to compare Sensoterra data with others and only look at relative changes/values, and users who only want to look at the relative soil moisture values and do not want to go through the process of choosing the right calibration.

There are caveats when using uncalibrated data, which are important to mention.The uncalibrated setting only shows relative values, ranging from 0 to 100. This value does not correlate with gravimetric or volumetric moisture content.

The resulting variation in values can be small for certain soils or situations (e.g., only showing differences from 60-65). This means users will have to zoom in to see clear variations in moisture content. This can be done by un-clicking “show too wet/too dry” (when stock setting are unchanged).

Users can still fill in the thresholds for too wet/too dry themselves. These can be determined with your own experimentation and derived based on your specific needs.

Calibrated data for VWC% and pF interpretation

The best way to get the most accurate data is to select a soil type which has been calibrated for in the Sensoterra Monitor App. We have more than +30 types of soils available in our standard calibration library, and selection is as easy as identifying where your soil is on the soil texture triangle. There are multiple methods, but lab analysis will offer the most precision. With the standard calibrations, we determine the too wet- and too dry- thresholds based on the soil texture analysis done at the Sensoterra Labs. These thresholds can be adjusted based on your own requirements, but often these suggested values offer precise VWC% to form the bases for precision irrigation.

For more on this check out our free soil calibration guide to learn more.

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