LaMotte SMART 2 Electronic Soil Lab - Manual (Page 49)

ELECTRONIC TEST METHODS
pH
PROCEDURE
1. Use the 10 g Soil Measure (1164) to add one level measure of the soil
sample to a 50 mL beaker (0944). Use the graduated cylinder (0416) to add
10 mL of deionized water. Stir thoroughly.
2. Let stand for at least 30 minutes, stirring two or three times.
3. Stir mixture just prior to making the pH reading. Determine the pH
reading of the sample by following the instructions for the pH Meter.
LIME REQUIREMENT -
WOODRUFF METHOD
PROCEDURE
1. Use the 10 g Soil Measure (1164) to add one level measure of the soil
sample to a 50 mL beaker (0944). Use the graduated cylinder (0416) to add
10 mL of deionized water. Stir thoroughly.
2. Let stand for at least 15 minutes.
3. Add 20 mL of Woodruff Buffer Solution (5272). Mix well, and let stand for
at least 20 minutes, stirring two or three times.
4. Take reading using the pH meter. Stir mixture just prior to making reading.
5. Each 0.1 pH unit drop from pH 7.0 indicates a lime requirement equivalent
to 1000 lbs calcium carbonate (CaCO
3
)/acre.
SMART2 SOIL MANUAL 4.08 49