User Manual

Instructions for measuring pH values
of soils and soil solutions
Measuring soil pH value
Once the meter has been set up and calibrated, using it to measure a pH values involves the probe, the green
dibber/auger, a soil/media sample and button functions.
NOTE: The probe tip must not have dried out. If it has dried, soak the probe in tap water for one hour prior to taking a
measurement.
1. Remove the top 5 cm / 2 in from the surface of the sample area.
2. Insert the dibber/auger into the sample to a depth of about 20 cm / 8 in and remove.
3. If the soil/media is dry, moisten with a small amount of distilled water.
4. Insert probe to the same depth ensuring it makes proper contact with the soil.
5. Turn the meter on.
6. Wait for the reading displayed on the meter to stabilize. This can take up to four minutes. Record the reading.
7. Remove the probe from the soil/media and wash with probe tip under fresh running water (not distilled) to remove
any remaining soil residue.
8. Repeat the procedure in different locations and take the average of the measured data as the pH level is
representative of the sample area.
9. Turn Meter off or allow instrument to turn off automatically (after four minutes).
If the meter turns off while taking a measurement, simply press the ON/OFF button to turn the meter back on and
continue with your measurement.
10. Store Probe between Measurements. Place wetting cap back on probe tip with a small amount of fresh water or
pH 4.0 solution in it or store probe tip in a container of fresh water between uses.
CAUTION: The Soil pH probe is never stored in de-ionized or distilled water as this will permanently damage it.
Measure soil solution pH value
The greatest source of error in soil analysis comes during sample collection. An effort should be made to ensure each
sample properly represents the area being sampled.
Note:
 The readings taken with this method could be higher than those taken by other methods
 Consistency of the method used is important to be able to compare sets of results
 The accuracy of this method cannot be guaranteed because of the variables involved
 The results should be viewed as 'indicative' rather than 'absolute'.
1. Collection of Sample
 Sample in a zigzag pattern across the required area.
 Remove 15 mm / ½ in of top soil before sampling at a depth of 150 mm / 6 in.
 Mix all collected samples together thoroughly.
 Allow to dry in air for one hour.
 Weigh out 20 g / 0.7 oz of the collected soil into a 150 ml / 5 fl oz plastic sample jar.
2. Sample Preparation
 Add 100 ml / 3½ in of distilled or deionised water, screw lid on tightly.
 Shake continuously for 5 minutes. Leave overnight and shake again the next morning.
 Allow to settle for 15 minutes after shaking and strain sample into clean measuring cup.
4. Take pH readings as follows;
 Insert probe into the soil solution sample
 Turn the meter on
 Wait for the reading displayed on the meter to stabilize. This can take up to four minutes. Record the reading.
 Remove the probe from the soil solution and wash with probe tip under fresh running water (not distilled) to
remove any possible soil residue.
 Turn Meter off or allow instrument to turn off automatically (after four minutes). If the meter turns off while taking a
measurement, simply press the ON/OFF button to turn the meter back on and continue with your measurement.
5. Store Probe Between Measurements
 Place wetting cap back on probe tip with a small amount of fresh water or pH 4.0 solution in it or store probe tip in
a container of fresh water between uses.
Bluelab Soil pH probe August 2009