Page 18 - Griffin Gazette Spring 2016

Bonus

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More tips on:
Media pH- Keeping the
Green Springin

By Rick Yates, GGSPro Technical Services Manager Testing Media pH and EC with the 2:1 Media Test
Materials Needed
Collecting Media Samples • Distilled water
Sampling methods vary slightly by test method. As with all aspects
of testing, random sampling and consistency of method contribute • Two 2-cup glasses or plastic measuring cups (Pyrex® with markings
greatly to the reliability of the resulting data. Sampling should occur works well)
in a random manner and should include samples from across the
majority of the crop. Fertilizer prills should be screened out of media • pH and EC meter(s)
prior to testing.
• Media sample(s)
SME and 2:1 Sampling Method – Preferred Method
1. Remove the pot from the plant, leaving the root mass and Test Procedure
1. Rinse container with distilled water.
associated media as intact as possible.
2. Measure ½ cup media sample at same density as found in pots.
2. Collect several tablespoons of media from a point near the center
of the pot. 3. Measure one cup of distilled water and add it to the media.

• Find a point about halfway down soil mass 4. Vigorously mix the sample.

• From this spot, pinch towards the center of the pot to collect 5. Cover to prevent evaporation and allow sample to settle for 60
the media sample minutes. Use a consistent settling time across all samples and
sampling events, but do not exceed 4 hours.
3. Collect samples from 5-10 pots selected randomly from as much
of the crop as possible. 6. Use meters to test pH and EC of the liquid layer above the settled
media.
4. Combined volume of ½ cup is adequate for in-house 2:1 testing.
Consult sample submission guidelines for laboratory testing as a 7. Rinse container thoroughly before storing or processing the next
larger volume may be requested. sample.

SME and 2:1 Sampling Method – Alternate Method
1. Collect a core sample from the pot.

2. Retain the middle 50% of the sample (discard the top and bottom 25%).

3. Continue with Steps 3 and 4 from Preferred Method.

Pour-Thru Sampling Method
1. Sampling involves collection of leachate from pots.