NCSU Horticulture Substrates Lab Publications and Presentations
 

The following is a step-by-step procedure for measuring pH and soluble salts in greenhouse crops using the PourThru method of soil sollution extraction.

Step 1

  • Irrigate your crop
  • Make sure you get thorough and complete hydration
  • Wait approximately one hour before proceeding with pourthru to allow adequate time for equilibration
Step 1

Step 2

  • Place a saucer under each container to be tested
  • We find that the inexpensive clear plastic pot saucers are good choices
Step 2

Step 3

  • For the pourthru, use distilled water
  • You can use the water from the grocery store
    • Be sure it is distilled and not just drinking water
  • The amount you use depends on the volume of the container
    • Use enough to get ~50 ml (milliliters) out of the bottom of the container
Step 3

Step 4

  • Pour the water evenly over the top of the container
  • Remember the water is used to displace the solution in the container
Step 4

Step 5

  • Let the container drain completely
  • Time will vary with container size but it should be completed in a few minutes
Step 5

Step 6

  • Pour the solution into cups or beakers for measurement
  • We find small plastic beakers are best so you can determine the actual amount of water drained
  • Variability in water applied and drained can lead to inconclusive results
Step 6

Step 7

  • 50 ml is adequate for testing in the grenhouse
  • This amount is also adequate for sending to diagnostic labs for nutritional analysis
Step 7

Step 8

  • Measure pH
  • Be sure to calibrate the pH pen or probe before use
  • Record value on pH graph
Step 8

Step 9

  • Measure soluble salts
  • Be sure to calibrate the EC pen or probe before use
  • Record value on EC graph
Step 9

Step 10

  • Check values on pH and EC tables and take appropriate actions

Charts and Guides*pdf*

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