17
VWC = 100*(M
wet
- M
dry
)/
(ρ
w
*V
tot
)
Where:
M
wet,
M
dry
= mass (g) of wet and dry soil respectively
V
tot
=
total soil volume (ml)
ρ
w
=
density of water (1g/ml)
An alternate, but equivalent, calculation can be obtained
from the gravimetric water content and soil bulk density.
VWC =
GWC *
(ρ
b
/ρ
w
)
Where GWC is the gravimetric water content and
ρ
b
is the
bulk density:
GWC =
100*(M
wet
- M
dry
)/M
dry
ρ
b
=
M
dry
/V
tot
The final step is to plot the calculated the measured period
values with the readings obtained from Field Scout TDR
meter. Regression analysis can then be performed on this
data to develop an equation to convert from period to
VWC.
