Home pH Testing of Soil

Hello folks...

Is there a way to test garden soil at home using one of the digital, pocket pH testers?

I have a Hach Pocket Pro pH Tester but am unsure how to go about turning garden and/or container soil into a liquid sample to test with the Tester.

I would imagine the pH of whatever liquid you would use to dissolve the soil would have to be taken in account when reading the pH that appears on the tester.

Thanks!

Mike

[Worth1]

Originally Posted by MikeBiondo

Hello folks...

Is there a way to test garden soil at home using one of the digital, pocket pH testers?

I have a Hach Pocket Pro pH Tester but am unsure how to go about turning garden and/or container soil into a liquid sample to test with the Tester.

I would imagine the pH of whatever liquid you would use to dissolve the soil would have to be taken in account when reading the pH that appears on the tester.

Thanks!

Mike

Just use distilled or RO water that way the PH will always be neutral.
You can also just test the water alone and this will tell you what the PH is of the water.
Pure water should be 7.

I then just turn the soil sample into a slurry to test the PH.
Works for me.

Worth

[moray-eel-bite]

Distilled or RO water are never actually 7. Because there are no buffering components left in them, they will often read as low as 5 simply because they are exposed to atmospheric CO2 etc (this is why global warming and excess CO2 from fossil fuels cause such problems. However, using distilled water to test the pH will work very well and cause very little interference. All this is to say that if you test the distilled water and don't get 7 that is to be expected.

Cheers.

[drew51]

Originally Posted by moray-eel-bite

Distilled or RO water are never actually 7. Because there are no buffering components left in them, they will often read as low as 5 simply because they are exposed to atmospheric CO2 etc (this is why global warming and excess CO2 from fossil fuels cause such problems. However, using distilled water to test the pH will work very well and cause very little interference. All this is to say that if you test the distilled water and don't get 7 that is to be expected.

Cheers.

Ha! Now that is funny. Current co2 is .04% Only one other time in earth's history has co2 been this low. Don't buy into the political stuff which is not allowed here.
Besides the fact that PH is a measurement of hydrogen ions. How many hydrogen ions in co2?
BTW I live surrounded by automotive factories. My rainwater is 7.0. A side effect of clean air. I grow blueberries and have to add acid even to my rainwater.
I use rainwater to test soil PH as it is neutral.

[moray-eel-bite]

Originally Posted by drew51

Ha! Now that is funny. Current co2 is .04% Only one other time in earth's history has co2 been this low. Don't buy into the political stuff which is not allowed here.
Besides the fact that PH is a measurement of hydrogen ions. How many hydrogen ions in co2?
BTW I live surrounded by automotive factories. My rainwater is 7.0. A side effect of clean air. I grow blueberries and have to add acid even to my rainwater.
I use rainwater to test soil PH as it is neutral.

Yes, pH is a measure of hydronium ions. CO2 becomes carbonic acid in water. CO2 is higher in the atmosphere such that the ocean is 30-40% more acidic than it was 100 years ago. Rainwater is not neutral, it's almost always acidic due to the lack of buffering capacity as stated above.
None of this is political, it's fact. Scientific fact.

Cheers.

[drew51]

Originally Posted by moray-eel-bite

Yes, pH is a measure of hydronium ions. CO2 becomes carbonic acid in water. CO2 is higher in the atmosphere such that the ocean is 30-40% more acidic than it was 100 years ago. Rainwater is not neutral, it's almost always acidic due to the lack of buffering capacity as stated above.
None of this is political, it's fact. Scientific fact.

Cheers.

Still sounds political to me. The CO2 is so low my rainwater is neutral.
Stating it is somehow high, goes against the historical record, and can only be seen as a political statement.
Also the fact that carbonic acid is rarely created when CO2 is dissolved in water, as it needs a catalyst for the reaction. Most CO2 stays as CO2 when dissolved in water. BTW Carbonic acid is used to put CO2 (The fizz) in your soft drinks. The reaction tends to go the other way, but hey nice try!

[RayR]

Originally Posted by drew51

Still sounds political to me. The CO2 is so low my rainwater is neutral.
Stating it is somehow high, goes against the historical record, and can only be seen as a political statement.
Also the fact that carbonic acid is rarely created when CO2 is dissolved in water, as it needs a catalyst for the reaction. Most CO2 stays as CO2 when dissolved in water. BTW Carbonic acid is used to put CO2 (The fizz) in your soft drinks. The reaction tends to go the other way, but hey nice try!

Carbonic Acid is a weak acid that can go through a few reversible reactions, it can turn back into H20 and CO2 or disassociate into an H+ ion and HCO3- (bicarbonate)

CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3-

Rain water will vary in PH (usually 5.5-6.2) partly because of the amount of carbonic acid formed, temperature and atmospheric pressure would have an effect, also rainfall from lighting storms is more acidic. Catalyst's for the reactions I suppose you could say. Also rain drops can pick up other contaminants on the way down like Sulfur Dioxide among other things that will change the PH.

[moray-eel-bite]

Originally Posted by drew51

Still sounds political to me. The CO2 is so low my rainwater is neutral.
Stating it is somehow high, goes against the historical record, and can only be seen as a political statement.
Also the fact that carbonic acid is rarely created when CO2 is dissolved in water, as it needs a catalyst for the reaction. Most CO2 stays as CO2 when dissolved in water. BTW Carbonic acid is used to put CO2 (The fizz) in your soft drinks. The reaction tends to go the other way, but hey nice try!

I have no interest is discussing this further, this is my last post in this discussion. CO2 levels before the industrial revolution average 180-280 ppm for approx. a thousand years. They are currently 360-400 ppm. This is very well documented. Even Wikipedia will probably document this. Carbon dioxide once in the atmosphere finds it's way into the ocean due to equilibrium chemistry. Also very well documented.
Put carbon dioxide into water where no (or lower than the equilibrium state) carbonic acid exists and it will form carbonic acid. This is simple chemistry. If you understood equilibrium chemistry you would also know that if you stuff enough of anything into an enclosed container you can reverse any reaction. This is why soda fizzes when you change the pressurization upon opening. Change in pressure equals change in equilibrium state. Either way, making soda pop with carbonic acid is not relevant to this discussion.
The earth's oceans have been repeatedly and repeatably measured to have increased in acid content. Again simply a fact.
Rain water in not neutral for the well reasoned and scientifically sound statements made by others in the couple posts above this. There are also some sulphur compounds and nitrogen compounds that contribute in small ways to the pH of rain water, but the main reason is certainly carbon dioxide and hence carbonic acid.
To the person who measured their rainwater and it's exactly 7: The instrument you used to measure it should be thrown away because it doesn't work. Invest in a quality instrument if you want to measure pH reliably. If the instrument you have can't tell the difference between 5.5 and 7 it's not worth using even for a home measurement.


And I'm officially done with the part of the discussion regarding carbon dioxide and carbonic acid and anything 'political'.

To those who this thread was actually meant for, who wish to measure pH in soils, there is no reason not to use DI or distilled water when diluting soil for a home pH reading.
If someone else has a question about measuring pH, I will happily answer.

Cheers.

[solid7]

Yes, but what you fail to mention, is that Distilled or RO water that has not been left exposed to ambient air, will still be fine to use for testing.

RO water into a sterile contiainer, or Distilled water, use immediately upon opening to make your slurry.

Test the water to confirm, in the manner mentioned above.

[Worth1]

Well I assumed that everyone had an RO filtering system so it would be fresh.

My bad.

Worth

[solid7]

Originally Posted by Worth1

Well I assumed that everyone had an RO filtering system so it would be fresh.

My bad.

Worth

I don't think it's a bad assumption, but it was a good point to raise bout the CO2 absorption. I used to raise aquatic plants, and when I first got into the hobby, I had a heck of a time with PH swings, and could never figure out why... ahaaa ha ha...

[moray-eel-bite]

For the purposes of testing soil even water exposed to the air and allowed to equilibrate will be fine. The concentrations of ions in the soil will swamp any CO2 contamination. The difference will be less than a 0.1 pH shift, which for soils and general testing is irrelevent.

[TomNJ]

I recall reading many moons ago that one should mix the dried and screened soil with distilled water in equal volumes, shake well, allow the soil to settle, and then measure the pH of the water layer. Can anyone confirm this? I would think that measuring a slurry would result in a varying amount of soil particles between the electrodes which may affect the readings.

TomNJ/VA

Thanks for the responses!

So, if I calibrate my pH tester with 7.0 buffered standard, and then take a reading my distilled water and it's not reading 7.0, is there any adjustment I can make to the soil pH reading I measure? In other words, if my dilution liquid is not neutral, won't that throw off the reading? And, if so, is there a way to extrapolate the correct pH from the tester reading, or do I just go out and try another bottle of distilled water?

Thanks again...

Mike

[Worth1]

I guess you could fool around with the water to make it 7.

Vinegar to make it go down and baking soda to make it go up.
Never really tinkered with it that much and I dont know where my meter is.

If you have your meter already give your tap water a test and see what it is.

A PH of 7.1 is ten times higher than a PH of 7, 8 is 100 times more alkali than 7 and so forth.

Worth