Testing soil pH

musashi

Site Moderator
Staff member
Found this, got from somewhere, thought it pertinent. The importance of doing a soil slurry test. This just verifies the accepted practice when analyzing soil properties.

From Fox Farms:
Receiving an accurate picture of the pH of soil can be very difficult. We do not recommend testing the soil pH by testing runoff or placing the probe directly into the soil. The pH buffers in our soils, such as oyster shell, will not register on your pH meter if you are testing the runoff or if you just place your pH meter in the soil. The oyster shell works as a pH adjustor once it comes in contact with water.
Make sure that you have a relatively new pH meter that is clean and calibrated according to the manual instructions. If you are testing for soil pH, we recommend that you perform a soil slurry test, as described below. This ensures that all of the pH adjustors within the soil work properly and register on your pH meter. It is important to note that the used soil may have a different pH than the new soil from the bag due to the pH of the irrigation water.

How to Perform an At-Home Soil Slurry Test to Determine Soil pH
Some gardeners like to be able to check the pH of their soil. Since actual soil pH can be difficult to determine without expensive lab equipment, we recommend a slurry test to determine the pH of your soil. Soil slurries provide a pH of the slurry, not the soil, and is used as an indicator of the soil pH. The soil slurry pH will be more acidic than the actual soil pH, which is to be expected. We recommend two slurries:

• A 1:1 slurry – mix 1 part soil to 1 part distilled water (by volume)

• A 1:5 slurry - mix 1 part soil to 5 parts distilled water (by volume)

• Thoroughly mix these slurries and allow them to sit for about 15 minutes

• Next, check the pH of the slurry with litmus paper, liquid indicator dye, or a digital pH meter

The 1:1 slurry of (SOIL NAME) should have a pH of OF: 5.0-6.2 HF: 5.0-6.3

• The 1:5 slurry of (SOIL NAME) should have a pH of OF: 5.6-6.7 HF: 5.6-6.6 CL:6.0-6.7 LW: 6.00-6.60

If pH values of the slurries are in the ranges provided above, you can assume that the pH of your soil is in the 6.3-6.8 range

* These pH ranges are based off our testing, which is done with tap water. Your municipal tap water may be different from ours, so your pH may be different as well.

If your soil pH is not within the correct range according to the soil slurry then you may want to adjust your soil. Dolomitic limestone will raise your pH and soil sulfur can lower the pH. Be sure to follow the manufacturer’s directions and water thoroughly after adding a pH adjustor so that it will be activated. If your pH is outside of the ideal range, your plants will not be able to take up nutrients and you will want to wait to fertilize the soil until the adjustor has taken effect. This can take up to 30 days. However, you can supplement with foliar fertilizers during that time regardless of the soil pH.


FYI- from what I understand happy frog ph tests should be in the range 5.0-6.3.
 
Very interesting.
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Arte Johnson, Rowan & Martin's Laugh In

* These pH ranges are based off our testing, which is done with tap water. Your municipal tap water may be different from ours, so your pH may be different as well."

Would it skew the numbers if you are not using their tap water? I am using non-chlorinated well water with a 9.0PH so I am already skewed! The plants seem very happy so I ain't gonna say Boo! I alternate with 5.0PH rainwater and the digital PH meter stuck in soil says 6.4 or lower. This is all so veeeery interesting. I am using Happy Frog Potting Soil.

Longball
 
Well my OCD got the better of me. Using litmus paper worked to keep pH in range but not knowing precisely got me buying another meter. This time I went with an Apera pH20 ($66) as my Groline went funky. Until it went bad it worked fine except the probe end was rectangular and not round. I could not insert the probe directly into my 3-gal containers and it was a PITA having to pour off, measure, pour back in, adjust and pour back out to measure. The Apera came in a nifty case and I am very happy with it so far. And I can stick it directly into my 3-gal container to measure pH saving me much time.
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mu
 
Well my OCD got the better of me. Using litmus paper worked to keep pH in range but not knowing precisely got me buying another meter. This time I went with an Apera pH20 ($66) as my Groline went funky. Until it went bad it worked fine except the probe end was rectangular and not round. I could not insert the probe directly into my 3-gal containers and it was a PITA having to pour off, measure, pour back in, adjust and pour back out to measure. The Apera came in a nifty case and I am very happy with it so far. And I can stick it directly into my 3-gal container to measure pH saving me much time.
View attachment 76561View attachment 76562

mu
I also switched to Apera after a very long time with Bluelab.
 
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