Garden soil testing is an important, but often overlooked task by beginners. I know it sounds difficult, but it’s actually really easy, and inexpensive too! So, in this post, I will show you exactly how to test your soil using a home testing kit, step by step.
There’s no need to send your soil sample off to some company, or pay for any expensive testing. Using a DIY home soil test kit is frugal, simple, and gives you very fast results.
Once you know what nutrients are lacking in your soil, you have the information you need to properly amend it, and grow your best garden yet!
Here’s what you’ll find in this step-by-step guide for how to use a soil test kit…
Why Should A Homeowner Perform Soil Testing?
All plants need nutrient rich, fertile soil to grow their best, stay healthy, and produce tons of flowers and vegetables for us to enjoy.
But it’s impossible to tell if your garden soil is healthy just by looking at it, you have to test it to know for sure. Using a home soil test kit is easy, and will quickly tell you if there are any nutrient imbalances.
When To Do A DIY Soil Test
It’s a good idea to test your soil at the end of every gardening season, so that you can add amendments before planting again.
Then you can test the soil again in the spring to check if the health has improved, and add any additional amendments that it may need.
How To Test Soil For Nutrients
Your soil test kit should come with instructions for use. So make sure you review those first, because they might be slightly different than my steps below.
My kit came with four different containers for testing each of the main nutrients. Pink for nitrogen (N), blue for phosphorus (P), orange for potassium (aka: potash) (K), and green for pH.
In addition to your kit, you’ll need a few other supplies before you get started.
Soil Testing Equipment Needed:
- Soil test kit
- Clean container (I used a kitchen bowl)
- Clean garden trowel or large spoon
- Distilled water
- Measuring cup (1 cup)
How To Collect Soil Samples For Testing
The first step for all four of the tests is to take a soil sample. Taking the sample is really easy, but you’ll want to make sure that your tools are clean first.
If you don’t have a trowel that’s easy to wash, then you can just use a large spoon from the kitchen.
Remove any mulch or debris from the top of a small area of your soil, and then dig down about 3-6 inches to take your sample (the garden bed I’m testing is new, so there isn’t any mulch on top yet).
In order to do all four tests, you’ll need a little more than one cup of soil (one cup for the N-P-K tests, and less than one teaspoon for the pH).
How To Test Your Soil At Home Step-By-Step
The instructions are identical for testing the N-P-K values, but slightly different for the pH. So, below I’ll break down the steps for both types of tests.
I’ll start with the pink, blue, and orange N-P-K soil test kit, so set your green pH container aside for now.
Testing Phosphorus, Potash, & Nitrogen (N-P-K)
Before jumping into the steps for testing the N-P-K levels, I wanted to give you a heads up that it takes a little longer to check these values than it does for the pH level.
That’s because, for these tests, you need to mix your soil sample with water, and let it sit until everything settles (which can take up to 24 hours).
So just keep that in mind when you plan to do your testing, to make sure you give yourself plenty of time.
Follow the steps below to use the phosphorus (blue), potash/potassium (orange) and nitrogen (pink) test kits.
Step 1 – Mix your soil sample with water: In a clean bowl, mix one cup of your soil sample with five cups of distilled water.
It’s important to use distilled water rather than tap water to ensure your test results are accurate (tap water contains chemicals and minerals that can skew the results).
Step 2 – Allow the soil to settle: Stir or shake your soil/water mixture for a minute or so, and then let it sit until everything settles.
Remember, you might have to wait a while to move on to step 3. Also, it will take much longer for clay soils to settle than for sandy ones (heavy clay can take up to 24 hours to settle).
You want the testing water to be as clear as possible, so it’s better to give it enough time to settle than to rush this step. To make it easy, I just let my soil sample settle overnight (I have sandy soil).
Step 3 – Fill test kit containers with sample water: Now that everything has settled, make sure you don’t move the soil sample/water mix, or disturb the muck at the bottom. You’ll only be using the water for these tests.
Fill both chambers of the N-P-K testing containers with your sample water up to the line towards the top. Your kit should come with a little dropper to make it super easy.
Don’t fill them all the way to the top of the container though, you’ll need a little bit of headspace to shake them up after you add the test powder in step 4.
But you do want the water level to be above the top of the colored boxes (it’s really hard to see, but there is a very faint dotted line at the top of left chamber to indicate the water level).
Step 4 – Add the test powder: Everything that comes with your type of soil test kit will probably be color coordinated like mine is.
There are colored capsules that come with the kit, and these contain the testing powders for each nutrient.
The color of capsule you need to use for each test matches the color of the lid for that container (i.e.: purple lid/capsule for nitrogen (N), blue lid/capsule for phosphorus (P), and orange for potassium).
I recommend doing this next part in an area where there’s no wind. You don’t want to inhale the powder, or get any of it in your eyes or mouth.
Carefully pull apart the capsule so that you can pour the powder into the left chamber of your test kit. You should only put the powder in there, not the entire capsule.
Don’t let any of the powder get into the water in the right side compartment (that needs to just be the clear test water).
Step 5 – Allow the test powder to dissolve: Put the cap back on the container, making sure it’s on there tight so the water doesn’t get mixed between the two compartments.
Then shake the container until the powder is dissolved in the test water. You may notice it changing color right away, or you might not see any change at all. So, let the N-P-K tests sit for 10 minutes before you read the results.
Testing Soil pH Levels
The soil pH tester is a bit different than the N-P-K ones, and it’s a lot faster. You’ll need less than a teaspoon of sample soil to perform this test.
But make sure you follow the same steps for how to take soil samples above to collect it (using clean tools, not your hands, etc.).
Follow the steps below if you’re using a DIY home kit to test the pH of garden soil.
Step 1 – Put your soil sample into the test container: Add a small amount of your soil sample to the left side chamber to fill it to the line (it’s really just a tiny bit).
I tried using the dropper thingy for this, but that does not work, so don’t do that. I found it easier to use a small spoon to get the dirt in there.
You don’t have to be too fussy or worry about getting dirt into the right side compartment. And if you accidentally fill it above the line, then you can just pour out the extra. No biggy.
Step 2 – Add the test powder: Grab one of the green capsules for this test (or the one that came with the kit you have).
Again, I recommend doing this part in a spot where there’s no wind. You don’t want the powder blowing away, or getting into your eyes or mouth.
Put only the powder into the water, not the entire capsule. So, carefully separate the two sides of the capsule, and pour the powder into the left chamber (right on top of your soil sample).
Step 3 – Add distilled water: Fill the rest of the left side compartment with distilled water up to the fill indicator arrow (this is where you can use the dropper thingy). Leave the right side of the container empty for this test.
It’s best to use distilled water for your pH test, just in case there are chemicals in your tap water that will skew the results.
Step 4 – Mix everything together: Put the cover back on your pH test, and snap it on tight.
Now you can shake the heck out of it to mix the soil and test powder with the water. Let everything settle for about one minute before reading the pH test results.
How Long Does It Take To Get Soil Test Results
The thing I like the most about doing my own testing at home with a DIY kit is that it’s really fast (and easy!). The preparation steps are what take the most time.
Once you’ve added everything into the chamber, the pH test gives you results in about one minute. Since you don’t have to worry about soaking your soil sample beforehand, total time for this one is only about 10 minutes.
The N-P-K testing takes a bit longer, since it’s a little more of a process to prepare your test sample. Once the containers are full, it only takes about 10 minutes before you can analyze the results.
But, plan for the total time of the N-P-K testing to take somewhere between 12-24 hours, depending on how long it takes you soil sample to settle in the water (heavy clay soils will take longer than sandy ones).
Analyzing Your Soil Test Results
To analyze your results, hold each one up to a source of natural light (not direct sunlight though). Then simply compare the color of the water on the left side with the color chart on the right.
It’s pretty easy to see if your soil is severely deficient in one or more of the N-P-K nutrients, because there will hardly be any color in the left side.
Basically, the darker the color is in the left compartment, the more of the specific nutrient your soil contains.
You can see from my N-P-K tests (photo below) that my soil is deficient in nitrogen (pink), sufficient in potash (orange), and has a surplus of phosphorus (blue).
Same idea for the pH soil analysis. Compare the color of your sample on the left to the chart on the right. The color chart will show you how acidic or alkaline your soil is.
You can see from the results of my pH test (the green one on the right), that my soil is alkaline.
Testing your soil is extremely helpful for growers of any level. Once you know the N-P-K and pH levels, you’re armed with the information that you need to properly amend your soil. No more guessing, now you know exactly what amendments to add to grow your best garden ever!
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- How To Fertilize Your Flower Garden Beds
- Lasagna Gardening 101: How To Make A Lasagna Garden
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