MPS-2 & MPS-6
4
RANGE AND ACCURACY
in accuracy of
±
(10% of r 2 kPa) over the range of
−
9 to
−
100 kPa.
Dry end
At water potentials drier than
−
100 kPa, both the MPS-2 and MPS-6
rely on the linear relationship between water content and the loga-
rithm of water potential that is a fundamental characteristic of soils
and the MPS-2 or MPS-6 ceramic disc. Laboratory evaluations have
shown good accuracy and low sensor-to-sensor variability to at least
−
1500 kPa (plant permanent wilting point). Field evaluations have
shown low sensor-to-sensor variability to
−
4500 kPa.(See Figures 3
and 4) Good accuracy should theoretically be achievable to this level,
and well beyond, but evaluation against accurate, independent water
potential measurements low water potential levels is problematic.
Figure 3: Time series MPS water potential data collected at 80 cm
depth under a Beech forest in Switzerland. Note the excellent sensor
agreement down to permanent wilting point (-1,500 KPa).
3
11
