How to measure the ph of your soil's runoff

How to test the pH of your soil mix

Measuring the pH of soil is just as important as with hydro applications, but few people know how to test soil pH to see if it is within the optimum range for growing robust healthy plants. Here I will try to explain my method of testing any soil / soilless mix, enabling me to spot any problems and correct them if necessary.

Firstly, wait till your soil has dried out and is due for its next watering schedule. Then take some plain water that you usually water your garden with, and adjust the pH to 7.0. You must make sure that you know the exact pH of the water going into your soil, and the neutral 7.0 is best, but anywhere from 6.5 – 7.0 will suffice.

Then place your pot into a bowl of some sort to catch the runoff water, and then start to water your soil slowly (with your pH- corrected plain water) till the water starts to drip from the bottom.
It’s the first drops of water that will give you the best reading of your soil, so make sure to water slowly till you see the first droplets. Then remove the pot from the bowl to eliminate excess water entering the bowl. Then perform the pH test on the runoff and compare it too your initial test.
The results of the runoff test will likely be lower than your starting value of 7.0. If this is the case, a small drop of 0.5 pH to 6.5 pH (example) would be ok and your soil needs no further alterations at the moment. But that’s not to say that it won’t need any future tests at all, just not at this time.

[Editor’s note: It may be beneficial to obtain an initial sample, as well as a ‘full flush’ sample in seperate bowls. In addition, test several plants in the garden just to verify your results]

What if the pH is off?
If your results prove to have dropped considerably, say to around 5.5 (which can happen in late stages of flowering), you will need to add some lime into your soil to help buffer the pH back up again.

Remove the first inch or so of soil, taking care not to damage any roots whilst performing this task. Then sprinkle the lime into the pot, nice and evenly at a rate of 1 teaspoon (5 ml) of lime per gallon of soil. Then replace the soil you removed earlier, and saturate the soil good to wash in the lime.

Do the same test next time your plants need watering just to check that everything is fine, if more lime needs to be added then just repeat the process again till you reach close to 6.5 – 7.0 with the runoff.

Ensuring that your pH is correct should be done throughout the life cycle; this will help eliminate any nutrient lockout that may occur. I recommend doing this once a month just to keep the PH in check, and you should never have a problem with deficiencies caused by pH lockout.

Great post , but if it so happens your ph is higher than 7 in the test what can you add to lower the ph ?

How can I raise or lower the pH of my soil mix?

Growing in soil and adjusting pH levels

A lot of gardeners have trouble with the pH of their soil. A high pH can lock out needed nutrients and mimic other problems like Fe and Mg deficiencies. The biggest mistake new growers make is to try and correct pH problems too quickly. The first step in determining if high pH is the real problem, is to pick up a good pH tester. Don't be afraid to shell out the cash for a good one, it's well worth it!

Here are some recommendations: (All sell for under $100.00)

1. Milwaukee makes two styles of hand-held pH meters. A small "pen" called the Sharp and the larger Smart Meter. Both are easy to use. The Sharp pens are splash-proof (although not totally waterproof), and have a large easy to read display. They also have a detachable, replaceable probe.

2. Oakton - Same type of pH tester as Milwaukee makes, but it's made a little better imho. These are totally waterproof. (It floats.)

3. Shindengen ISFET pH Meters are state-of-the-art pH pens and work with a totally different method of measurement. This pen uses a solid state Ion Sensitive Field Effect Transistor (ISFET) instead of the fragile glass electrodes used by traditional pH pens. They have replaceable tips that change from opaque to clear when they need to be changed.


What is pH, and what do the terms acidic and alkaline mean?
The acidity or alkalinity of the soil is measured by pH (potential Hydrogen ions). Basically it's a measure of the amount of lime (calcium) contained in your soil, and the type of soil that you have. A soil with a pH lower than 7.0 is an acidic soil and one with a pH higher than 7.0 is considered to be alkaline. A pH of 7.0 is neutral.


Adjusting your soil pH :
Once you have determined the pH of your soil with a good tester, you can amend the soil if needed to accommodate the plants in your garden using inexpensive materials commonly available at your local garden center.

Adjust soil pH slowly over several days time, and check pH often as you go. Radical changes in pH may cause osmotic shock damage to the roots.


Raising soil pH : (to make it more alkaline)
It is generally easier to make soil mixes more alkaline than it is to make them more acidic. The addition of dolomite lime, hardwood ash, bone meal, crushed marble, or crushed oyster shells will help to raise the soil pH.

by MisterIto
In soil: add dolomite limestone to the soil; use small amounts of hydrated lime.

Raising hydroponic pH : (to make it more alkaline)

In hydroponics: use potassium silicate, provides silicon at an effective doseage.
In bioponics/hydro-organics: add small amounts of sodium bicarbonate or lime.

Lowering soil pH : (to make it more acidic)
If your soil needs to be more acidic, sawdust, composted leaves, wood chips, cottonseed meal, leaf mold and especially peat moss, will lower the soil pH.

by MisterIto
bloodmeal/cottonseed meal during vegetative; bonemeal during flowering.

Lowering hydroponic pH : (to make it more acidic)

In hydroponics: use nitric acid during vegetative; phosphoric acid during flowering.

Contributed by: Spiritual.Fa
23-08-2003

Stabilizing pH with Dolomite lime

The best way to stable PH is by adding 1 ounce of Dolomite Lime per 1 gallon of planting soil.

Dolomite Lime is available in garden nurseries. Buy the fine Dolomite powder (There may be several kinds of Dolomite like Rough, Medium, Fine)

Dolomite Lime has been a useful PH stabilizer for years, since it has a neutral PH of 7 when added to your soil it stabilizes your soil at PH 7.

Mix the dry soil medium and dolomite together really well, give the mix a good watering then after the water has had chance to settle and leech into the soil a bit give the mix a really good stir. Then water the soil/lime mix and give it another stir

Best plan is to mix fine dolomite lime into your mix before planting. Fine Dolomite will help stabilize your pH; however, if the ph becomes unstable or changes, you can then use Hydrated Dolomite Lime. Add some of the hydrated lime to luke warm water and give it a good stir then water your plants with it. Give the plants a good watering with this hydrated lime added and your PH should fall or rise back to 7

Other Benefits of Dolomite Lime

Dolomite lime is also high in two secondary nutes that can often be overlooked by fertilizers; dolomite is high in both (Mg) Magnesium and (Ca) Calcium.

Need to read this when i get home... =]

EDIT>>>
Done... =]

Good read... =]

can i raise my the ph of my soil by raising the ph of the rez?

it is very important,thanks

Thanks!!!
Exactly what I was looking for

this is good stuff

thanks for the tip.

super awesome,

awsome! posts like this is y i love RIU +rep

Great post +rep!

I found a site that took your post and claimed it as their own. Taken, word-for-word, but I guess imitation is the greatest form of flattery.

http://www.kindgreenbuds.com/marijuana-grow-guide/raise-or-lower-soil-ph.html

lolz, i clicked the link and it IS the same

yo nice post (i know its old as shit) it helped out like a mofo. nothing was wrong with my ph but it was good to have this info here because i was able to check and make sure my soil was on point.

just wanted to point out that liquid lime is a good substitute for dry and for an established plant is easier to administer. i use aggrene liquid lime about 1 tablespoon per gallon on plants if they need it. even when you mix lime in the soil before planting a long grow cycle can deplete it and weaken its ability to buffer the soil.

Great Post-thanks!

isnt the run-off pH that you get from the results of the test like a half way point? I read somewhere that if you use a 7.0 pH going in and it comes out at like 7.3, that it's really at about 7.6 or if it's 7.0 going in and then 6.0 out, it's really at about 5.0...the amount that it's off from the 7.0 is like a half way point?

Or am I just making stuff up?

run-off means nothing. it is not a measurement of soil ph.

scroglodyte said:

run-off means nothing. it is not a measurement of soil ph.

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i completely agree.. run off ph tells you nothing but the ph of your runoff...

racerboy71 said:

i completely agree.. run off ph tells you nothing but the ph of your runoff...

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I have also heard this as well. If this is the case (that it doesn't matter), why wouldn't the soil run-off be an indicator of the soil's pH? If you are watering with a 7.0pH in and it comes out higher or lower, something had to change the pH and it's different coming out. So wouldn't that give you an idea that if you now put 6.5 going in, the same changes are happening with in the medium, making the pH of the water lower/higher? And I have also heard, with container gardening, the pH fluctuates anyway, so if you just keep watering with the pH you want, over time it will adjust itself?