page37
37
2.1 Physical Characteristics
Note: If soil moisture is at or near field
capacity, you can end the test after step 8. The
moisture content of the soil will affect the rate
of infiltration; therefore, two infiltration tests
(see step 9 and 10) are usually performed if
soil is dry. The first inch of water wets the soil,
and the second inch gives the estimate of the
infiltration rate of the soil.
Number of minutes
Number of minutes
is no longer under water and is just
glistening.
9.
Record the
10. Repeat infiltration test in the same
ring, with a second 15 oz (444 mL)
of water.
11. Record the
elapsed for the second infiltration
measurement
Calculations
1.
Calculate the fraction of an hour it
took for 1 inch of water to infiltrate
into damp soil:
2.
Calculate the infiltration rate:
Interpretation
Using the chart, how would you interpret the
infiltration rate of your soil? What physical
characteristics do you think are responsible
for the infiltration rate you determined?
Number of
minutes
÷ 60 =
Fraction of
an hour
÷ 60 =
__________
__________ min
Infiltration
rate
1 inch ÷
=
=
Fraction of
an hour
________ in/hr
1 inch ÷
__________
Infiltration rate
(inches/hour)
Infiltration
class
> 6
Rapid
0.2 to 6
Moderate
0.0015 to 0.2
Slow
less than 0.0015
Impermeable