Soil testing, a tutorial for pH, N.P.K. solves most problems

Hi it’s your Uncle_Al again, I have been watching as quite a few members here are chasing their tails trying to solve their sick plants problems. On OG 1.0 I was a moderator assisting fellow growers solve the very same problems I see here. So let’s get to the root of the problem you guys are not soil testing. I see many of you check pH of your water, and that’s a great start but it is not the whole picture. The soil, or growing medium needs testing too.
Things you will need to accomplish a soil test

  1. You will need a actual soil test kit, they are available at all the big box stores garden center.
  2. A large clear vessel to mix soil and water in.
  3. A syringe or quality dropper.
  4. A simple aquarium pH test strips.
  5. A measuring container, it does not need to be a Pyrex measuring cup.
  6. A clean source of water preferably not tap water, purified by reverse osmosis and filtered with no flavor additives.
  7. A representative sample of your soil
  8. A spoon or spatula to stir a soil sample with
  9. An hour or so of time
  10. The ability to follow directions as they are written, no making it up on your own.

These are the items we will use in this tutorial.

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First we have to check out our test water to make sure it’s good, remember I said follow directions don’t take short cuts.
Pour a little water in the mixing glass you won’t need much , then open the package for the aquarium pH strip. Notice the pH scale. You may use a different type of strip there are many.

Now dip the strip in the water, hold the strip level while the color develops, this strip takes 15 seconds count 1 Mississippi 2 Mississippi… then compare the color to the chart on the wrapper.


Water looks like it’s right between 6.2 and 6.8 that’s good enough to work with.

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Let’s look inside the test kit.

Inside are four color coded vials in a stand, there is a silver pouch with four bags of color coded capsules. A card with written instructions to follow, there is a crappy eye dropper that I promptly throw away in lieu of my personal favorite. If you don’t have a syringe you will need the crappy eye dropper.

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Let’s perform the soil pH test first, take the green vial remove the cap. Now hold it up to the light and notice the 4 lines that go around the vial these are for measuring.

Fill the vial with some of your soil sample to the first line.avoid filling it with perlite, stones or chunky stuff.

Now take a green capsule it is filled with a powder, you will need to open it up by separating the halves of the capsule, I recommend doing it over the instruction card to catch what falls out.

Now carefully slide the powder into the vial.

Place the vial in the rack so you don’t knock it over, Now take the syringe or dropper and collect enough water to fill the vial to the fourth line. Wait for a couple of air bubbles to rise and top off to the fourth line

Cap off the vial and shake it until your arm hurts.most of you are very familiar with the motion, just be sure to hold the cap in place or the juice will fly out prematurely,which I think most of you are also familiar with.

Now we wait a couple minutes for the material in the vial to settle out to the bottom and the chemical action to develop

Now compare the color of the liquid in the vial to the chart in the instructions.

Looks to be about a 5.5 according to the chart.
That’s not good for a plant we have to move that pH up, this tutorial is not about what product to use in adjustment. We are going to continue with the testing.

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The next part of the soil test requires soil preparation, take 1 part soil and 5 parts water, dump the soil in the mixing vessel
One cup soil

And five cups of the water we tested earlier.

Now stir the mess up using the spoon or spatula. Do this for a whole minute or two.

This next step will be the hardest part, you have to wait for the material you just stirred up to settle out enough to get a clean sample this could take anywhere from an hour to overnight depending on what the soil is made up of. I will be back in a few minutes to check on the status.

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Through the miracle of television we have a test sample ready to check out

This is not from the test mess we stirred up but rather from a bucket of soil & water from the basement.

The directions at this point are easier and the same for the N.P.K. tests open the color coded vial , then open the corresponding color capsule. (Over a piece of paper) and slide the powder into the vial fill the vial with the test sample water shake the mix up like previous and in ten minutes allowing the color to develop compare the color to the chart

Vials in rack developing.

Nitrogen test= very high actually higher than the chart

Phosphorus= high

Potash= very high it is darker than the scale.

So what does it all mean Uncle_Al ?

What it means is this freshly mixed soil that has no added nutrients is very hot and will burn the leaves off the plant, this soil needs further amendment to raise the pH and lower the nutrients a whole lot.
This my good growing friends is why you must soil test first before planting your beans this is also why you should not begin feeding you seedling right away
This my friends is why so many of you are having problems, I sincerely hope you take this lesson to heart.
Thank you and good growing.

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Seems extra important. :money_mouth_face:

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This is a marvelous tutorial @Uncle_Al, thanks for taking the time to explain in such detail and step by step. Gonna go get me the soil tester… Thanks again.

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How good are these tests? Have any results of this vs lab tests? Ive never trusted them. You can send soil off to a lab around your area and get a legit soil test done. Its not too expensive and its worth it if youre having problems.

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I have used these soil test kits for years now they are very reliable, and at the price point there are 10 complete test in the package. Some communities have a county agricultural extension office that will do the same thing for free,I don’t want contact with them myself, but feel free to pay more if you’re still nervous

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No Uncle i will use the ones you showed, have to get them tho. That’s what amazon is there for…

Again, thanks Uncle…

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Very good then you will soon be on the right track

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I have one of those test kits somewhere. I have never used it, might be fun to play with. :slight_smile:

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I’ve actually avoided these tests because they’re usually shelved next to those cheap-ass pH/moisture probes that do nothing, so assumed these were half-baked, too.

I’ll give it a shot – might learn something interesting about the soil I’ve been using, and will be extremely helpful for the soil I’m cookin’.

Thanks for the amusing and informative tutorial!

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The kits are full of science stuff no magic hokum

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I appreciate that so many of you are commenting on this thread of mine it is really warming my heart , I am feeling the love I appreciate all the positive comments

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I havent used a test kit in a loooong time. only lab results now

"Soil testing is an important component of a plant nutrient management program for farmers, home gardeners, and agricultural service personnel. Results from five commercially available colorimetric soil test kits were compared with standard laboratory analyses for pH, nitrate–nitrogen (NO3), phosphorus (P2O5), and potassium (K2O) content for Salinas clay loam soil with three cropping histories. The kits ranked in accuracy (frequency of match with analytical laboratory results) in the following sequence: La Motte Soil Test Kit, Rapitest, Quick Soiltest, Nitty-Gritty, and Soil Kit at 94%, 92%, 64%, 36%, and 33%. NO3 was most accurately determined by Rapitest and Quick Soiltest, P2O5 by Rapitest, and pH by La Motte Soil Test Kit. K2O was determined with equal accuracy by all but Soil Kit. The composition of the extractants may be an important factor affecting the accuracy of the test kit. For example, all kit extractants for K2O were composed of the same chemical and matched analytical laboratory results 82% of the time. By contrast, kits using an acid-based extractant for NO3 analysis more frequently matched the analytical laboratory results than kits using a zinc-based extractant (P ≤ 0.0001). La Motte Soil Test Kit had the largest range of pH measures, whereas Rapitest was relatively easy to use and interpret and is a practical choice for home gardeners or landscapers; both were more than 90% accurate for this soil type. Although an important limitation of commercial test kits is the approximate or categorical value of nutrient content (i.e., low, medium, high), accurate test kits can yield results quickly and economically for improved nutrient management. "

 Ben A. Faber1, A. James Downer1,3, Dirk Holstege2 and Maren J. Mochizuki1
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So many guys are not testing at all that is the point here, if you go cheap that’s what you get.

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Heres a good read and video on testing these at home soil test kits and a lab. Soil pH Testers-Are They Accurate?

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I particularly am happy with this thread. Super useful and insightful.

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