How to Get the Most Accurate Soil Moisture Data

The first step to understanding if you are collecting quality soil moisture data is to first know where they’re wrong. But what makes good data go bad?

Proactive prevention of data’s main confounders.
Would you recognize bad data if you had it? Knowing what to look for and the key steps to take to prevent later problems is the difference between accuracy and estimation. In this 30-minute webinar, METER’s soil moisture sensor product manager and ecology and plant physiology specialist, Chris Chambers, will break down the largest contributors to degradation in data.

Discussed in this webinar:
The impacts of an inaccurate or unreliable sensor
How incorrect installation can invalidate all data
How to preempt installation issues before they occur
How to minimize the possibility of preferential flow
What METER is doing to help you get the most accurate data possible
And more

3. INTRODUCTION

About Me

+ Background in Forestry and
Physiological Ecology

+ 15 years of experience working
with soil moisture sensors and
soil moisture data

+ Many conversations with
scientists about soil moisture

4. VOLUMETRIC WATER CONTENT

Water Content: Amount
- @ is volumetric water content (VWC)
- V,, is the volume of water
- Vr is total sample volume

~

6. 1. SENSOR PERFORMANCE

Not all sensors are created equal

・ Price vs performance

・ How well does the sensor measure the electrical properties of the soil
・ How much does one sensor vary from another

9. TEROS 10

+ Analog
+ NOT normalized

+ Verified at the factory to fall
within a range

10. TEROS 11/12

+ Every sensor is individually
normalized before it leaves
the factory

+ Dials in the sensor to an

electronic target over a range
of mimicked water contents

+ Reduces sensor to sensor
variability

12. •
•
-4.00%
-3.00%
-2.00%
-1.00%
0.00%
1.00%
2.00%
3.00%
0 5 10 15 20 25

13. SENSOR PRECISION

+ In the end you will need fewer replicates for
TEROS 11/12s with their increased precision

+ Is the TEROS 11/12 worth the extra expense
for the extra precision?

16. •
•
•
•
•
•
•
•

21. BACKFILLING

+ Be careful not to disrupt the
sensors or cables

+ Pack back to the original density

23. METADATA

Water content means something
different in a sand than in a clay

So, you are really going to need the
metadata

・ Record site specific data,
especially soil type

ㆍ Grab a soil sample

26. 3. QUALITY ASSURANCE/VERIFICATION

+ How do you know that your sensor is working properly?
+ Is there a standard?

+ When should | worry about my soil moisture data?

+ Soil moisture hasn't moved in weeks. Is my sensor ok?

31. MY RED FLAGS

+ Sensor shoots out of range high or low
— TEROS 12 normal range is: 1800 (air) to 3300 raw counts (water)

+ Sensor reads really erratically

33. RISKS TO YOUR DATA

+ Poor contact with the soil
+ Preferential flow through backfill channels or along cables
+ Incorrect categorization of soil type

34. 0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0 5 10 15 20 25 30 35
V
o
lu
m
e
t
r
ic
W
a
t
e
r
C
o
n
t
e
n
t
(
m
3
/
m
3
)
Dielectric
1.5 g/cm3 Bulk Density
1.0 g/cm3 Bulk Density

35. METER WORKS ON
THE COMPLETE PICTURE

+ Top notch sensor precision
+ High quality, repeatable installation
+ Testing and verification