ICT MP306, Руководство по эксплуатации, Страница: 6 / 9

MP306 Moisture Probe Operation Manual
The results from measurement of the absolute volumetric soil water percent (VSW%) using the MP306
when compared with TDR technology are given in Figure 2. This result is typical of the results obtained
from comparative testing of the MP306 compared to TDR technology for a wide range of agricultural soils.
MP 3 06
TDR
0 5 10 15 20 25 30 35 40
TDR Volumetric Soil Water (%)
Figure 2. The MP 3 06 in comparison to TDR Measurement of Absolute Volumetric Soil Water Percent as
a Standard.
2.3.3 Definitions
Gravimetric Soil Water Content is defined as
θ
G
= Mw
Where
Mw
is the mass of water in the soil sample
Ms
and
Ms
is the total mass of the dry soil sample.
Volumetric Soil Moisture Content is defined as
θ
V
=
θ
G
* Ps Where Ps is the bulk density of the soil sample ( = Ms )
( Vs )
Where Ms is the total mass of the dry sample and
Vs
is the total volume of the dry soil sample.
Volumetric Soil Water Percent (VSW%)
VSW% =
θ
v * 100
The
VSW%
typically varies in the field from 2–5% for sandy soils at permanent wilting
point to 45–55% for clay soils at saturation.
Volumetric Soil W
ater (%)
A Comparison of the MP 3 06 and TDR
as a Standard
40
35
30
25
20
15
10
5
0