5
5
Measure Soil pH Directly
5.1
Remove about 2 inches (5cm) of the top layer soil in the test area,
make sure the soil is wet
. If the soil is dry, pH measurement
cannot be performed, and the probe can be damaged. For dry soil,
please add some distilled or RO water to moisten. Ideally, wait 24
hours before measuring.
5.2
Use the dibber to create a pathway for the spear probe at about 4-6 inches (10-15cm) in
depth. This will help minimize the wear and tear of the spear glass probe.
5.3
Remove the probe cap; power on the pen; rinse the probe in the
water bucket and shake off excess water.
5.4
Insert the probe in the hole you just created up until the bottom
where you cannot stick in any further (do NOT use excessive force
to stick in); Wait for the reading to fully stabilize (
stays on screen),
then press
to hold the reading. Then take out the pen
and record the measurement.
5.5
After each test, the probe must be thoroughly rinsed in the water bucket. Make sure to
clean off the dirt on the white PTFE junction ring using the cleaning brush. Avoid brushing
the spear glass tip. After cleaning, shake off excess water. For details of probe cleaning,
refer to Section 8.
5.6
Repeat Step 5.2 to Step 5.5 to record 3-5 measurements in different locations of your
sample area, then calculate the average value. After measurement, put the probe back
in the storage cap and soak in the 3M KCl solution.
The recommended pH range for soil crops is 5.8 to 7.2 pH. And the best pH range for each plant
is different. The factors that are affecting the soil pH include soil type, growth stage of the plant,
use and types of fertilizers, use of pesticides, and the s
oil’s temperature.
In the practice of direct soil pH testing, as soil is not evenly distributed by its nature, different
locations and different depth will generate slightly different pH readings. Even when the angle
at which you stick in the probe is different, the reading can also be affected. Therefore, selecting
multiple locations while doing your best sticking in the probe at the same depth and angle, then
calculating the average is the best way to compensate such reading errors and maximize the
measurement accuracy.
