Gardening experts everywhere recommend that you test your soil before doing anything else.
And, if your garden is suffering, you’re just starting out as a gardener, or you’re a serial fertilizer, I recommend the same.
Understanding the nutrient composition and pH of your soil can help you troubleshoot problems and fertilize appropriately, which can make a huge impact on the overall health and productivity of your garden.
But how in the world do you test your soil?
Well, you probably shouldn’t – the pros should.
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Store-bought kits are widely available, but their accuracy is questionable at best. In particular, if the pH is only less than one degree in either direction, any modification you make may do more harm than good.
And while the kits are relatively inexpensive and you can usually get more than one use out of them, you’re on your own to interpret the results and figure out a plan.
If you send a sample to a laboratory to be professionally analyzed, however, you are guaranteed more accurate results.
Not to mention, you’ll usually be given tips for fertilization and amendment depending on the type of plants you plan to use.
Keep reading to learn who should get your soil tested, how to get a sample from them, and what you should do with the results.
Who are the professionals?
The best way to get your soil professionally analyzed is to contact your local extension office in your state or county.
If you have no clue what I’m talking about when I say “local extension office,” you’re not alone. This is one of those often referenced, blanket statements of advice that are rarely explained.
In short, the USDA supports an effort known as the National Institute of Food and Agriculture (NIFA) Cooperative Extension System (CES).
NIFA refers to CES as “a nationwide, non-credit educational network that serves public needs by providing non-formal higher education and learning activities to farmers, ranchers, communities, youth and families throughout the country. “
Basically, your local extension was created for you. So, use it!
For a nominal fee, usually between five and $25, your local extension office will test your soil for you.
In some areas, services may also be available at county offices. For example, here in Cincinnati, Ohio, the Hamilton County Soil and Water Conservation District provides soil testing services to residents.
No matter which service you use, the procedures are the same across the board.
How to collect soil sample
A kit will be sent to you with instructions on how to collect a quality sample. Usually, it goes something like this:
Step 1 – Create a Nail
Use a trowel to drive a V-shaped wedge into the ground about 2 inches wide and 6 inches deep.
Step 2 – Remove and Cut
Lift the nail off the ground and cut a section two inches from the center of the sample.
Step 3 – Set aside
Place the sample in a clean, non-metallic bucket or bowl of some sort.
Step 4 – Repeat
Repeat Steps 1 through 3 in 8 to 12 more locations, depending on the size of the area you’re sampling. This will give you a more comprehensive picture of the area you are testing.
Step 5 – Combine
Mix the samples thoroughly, and allow the mixture to dry completely.
Place the required amount — usually less than a cup — in the designated container, most likely a plastic bag.
Step 6 – Documents and Mail
Fill out the required information sheet (one should be included) and mail off the sample.
If you are sending more than one sample, be sure to record where each sample was collected.
Most of the action happens close to the surface, so don’t worry about sampling deep.
Organic matter, nutrients, organisms and plant roots are most concentrated in the top four to six inches of soil.
Sending a sample is not something you should do every season. Every three to five years should be sufficient. Stick to the same lab each time for the most consistent results.
The best time to send a sample is in the fall, but early spring is good too. That way, any amendments you make, such as adding organic fertilizers or lime to raise the pH, have time to take effect.
good to know
Do not assume that the exam will be all-inclusive.
Typically, basic nutrients — such as phosphorus, potassium, calcium, and magnesium — are tested along with pH and organic matter.
All plants use the macronutrients nitrogen (N), phosphorus (P), and potassium (K) in the highest amounts, which are the nutrients found in commercial fertilizers.
However, nitrogen is not commonly tested because it moves easily in and out of the soil and any readings can change quickly.
Providing adequate organic matter, rotating crops and using cover crops all help ensure adequate nitrogen levels for plants.
A working compost bin.
Many tests will give you an idea of texture, along with recording the percentages of sand, silt and clay. It’s really helpful to know about drainage, moisture retention, and air circulation.
The ideal loam texture that garden articles like to recommend for planting is composed of equal parts silt, sand and clay, 45 percent of the total.
Believe it or not, there should be up to 50 percent open pore space. At any given point, half of the open pore space should be filled with water, the other half with air.
Loamy soil is ideal for most vegetable and annual gardens.
and organic matter, which is nothing more than rotting sticks, leaves, grass clippings, animal waste, and should generally be about 5 percent in healthy gardens.
Call your extension office and speak with someone before mailing your sample, and ask what is included in the standard test. You may have to make special requests if you have specific concerns.
For example, if you want to test for heavy metals, such as lead, you may have to ask (and pay a bit more) or possibly even go to a private lab. But it’s often worth the extra cost and effort if you plan to grow an edible garden, especially in urban areas.
what to do with the result
Once you receive the test results, this information will be accompanied by fertilization and amendment recommendations, especially for nutrients and pH.
Keep in mind that recommendations will be different for different crops. Therefore, it is really important to provide the lab with information about what you want to grow.
For example, turf, vegetables, flowers and shrubs will all differ in their general soil requirements.
My favorite method of fertilizing is organic. It’s as good as gold.
However, the freshly added manure needs to be worked on by organisms before the nutrients are readily available. So think of compost as a long-term, slow-release fertilizer.
Add a few inches of fresh, organic compost once or twice a year and the soil should be well fed.
This is correct. The soil must be well fed. It’s an ecosystem with bacteria and fungi and insects, and a host of others working collectively.
Most commercial fertilizers are for feeding plants, not soil. They typically include only nitrogen, phosphorus and potassium in manufactured forms that are immediately available to plants, but with little to life underground.
Excessive use of synthetic fertilizers can actually harm the life of the soil in the long run. Some nutrients will favor some organisms over others, so diversity can become an issue.
And, at least in the short term, fertilizers are known to reduce nematode populations and may harm fungi.
They quickly outgrow the garden, which means you’ll need to replant them during the growing season.
With that said, I recommend chemical fertilizers in the short term if you have acute nutrient deficiencies. Test results and recommendations for correcting nutritional imbalances will be especially useful.
Dr Prithvi Organic Fertilizer
Try an organic fertilizer like Dr. Earth’s, available on Amazon.
Adjusting the pH may also be recommended. Usually, this can be accomplished by adding lime if the situation is too acidic, and lime if it is too alkaline.
Most plants will do best in slightly acidic to slightly alkaline conditions. If the pH falls below 5.5 or above 7.5, adding lime or sulfur would be recommended.
A pH of 6.0 to 7.0 is ideal for general gardening. In this range, nutrients are readily available and life flourishes below ground.
build a healthy foundation
Having an understanding of nutrients and pH, as well as texture and organic matter, makes it that much easier to ensure a healthy, thriving garden.
You’ll also be less inclined to fertilize more, which, depending on how much fertilizer you use each year, could save you some money.
Once you’ve got your plants growing healthy and in the short term, put chemical fertilizers aside and focus on feeding the soil.
Healthy, diverse, nutrient-rich soil produces healthy, nutrient-rich plants.
Even if you don’t intend to eat the plants you grow, they will be stronger and more resistant to pests and diseases if the soil is well-drained.
Add two inches of organic compost to your garden, once in the spring and again in the fall, just as you would any other organic fertilizer. Insects and other organisms will work with it and convert it into usable plant nutrients.
Planting cover crops like clover and winter rye is another great way to maintain healthy soil.
Clover is much more than a weed.
They are typically planted during the off-season on fallow land or between orchards and can protect against erosion and weeds, as well as feed underground life.
Keep on an annual healthy rotation schedule each season to further encourage variety and keep nutrients balanced.
And, you’ll want to avoid over filling and compacting your garden as much as possible.
Think about tilling your soil before you grow your plants and you’ll be on your way to a beautiful, productive, healthy garden.
Have you had your soil tested before? what was your experience? Share with us what you learned in the process in the comments section below!
And for more tips on techniques for improving soil in your garden, check out these guides ahead:
Photos by Amber Shidler © Ask the Experts, LLC. All rights reserved. See our TOS for more details. Originally published on April 9, 2018. Last updated on April 10, 2023. Product photo via Dr. Earth. Uncredited photos: Shutterstock.