If you use Fox Farm soil you will want to read this

I have been having a problem with my Ocean Forest soil being too acidic with runoff PH at 5.5. I also did a slurry test yesterday with some of the leftover soil still in the bag and it came out at PH of 5.3. I sent a message to Fox Farm customer service asking them why my soil is so acidic when it is supposed to be buffered to 6.4. This is the reply I received and I don’t know what to make of it. It goes against everything I have read about runoff PH. I am interested to see what you guys think of this response. Maybe it is true and maybe they are “blowing smoke” up our butts. LOL.

"All FoxFarm soils come pH adjusted right out of the bag between 6.3 and 6.8, which is the ideal range for plant nutrient availability. In order to ensure that your soil pH remains in the proper range, we recommend that you adjust the pH of your nutrient solution between 6.3 and 6.8, alternate feedings and waterings, and periodically flush your soil of excess salts.

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 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.

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 Ocean Forest should have a pH of 5.0-6.2

• The 1:5 slurry of Ocean Forest should have a pH of 5.6-6.7

• 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. Additionally, these tests were done on soil directly out of the bag. Because you have been using your soil, the pH may have been impacted by the various inputs."

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