Soil Sample Testing: 17 Things (2021) You Need To Know

If you’ve never gardened or farmed previously, chances are you’ve never thought twice about the soil on your land or about having soil sample testing done.

Yet, as a landowner, soil can drastically impact both you and the people around you.

You may not realize it but applying too much or the wrong type of fertilizer can harm your crops, waste money, and affect local coastal waters and drinking water.

Don’t waste any time!

Do soil sample testing to help correct soil problems as soon as possible.

Keep reading to learn everything you should know about soil testing.

1. What is soil?

Let’s start at the very beginning!

Soil is material composed of five ingredients:

bulletMinerals

bulletSoil organic matter

bulletLiving organisms

bulletGas

bulletWater

Soil provides nutrients to plants and serves as their foundation to grow.

If you don’t have healthy soil, you won’t have healthy plants.

Likewise, if you increase the health of your soil, then you’ll improve the health of your plants.

This is where soil sample testing comes in.

We’ll talk more in-depth about what that looks like below.

2. What is soil sample testing?

A soil sampling test refers to the numerous tests that are done to estimate the plant-available concentrations of plant nutrients.

Often, this test focuses on pH as well as other nutrients that are necessary to sustain agriculture and other life.   

3. Why should I have my soil tested?

Soil sample testing helps you determine your soil’s pH as well as which elements are missing.

Plant growth relies on soil pH and the balance of nutrients.

If these factors are off, then your crops won’t grow correctly.

Having your soil tested periodically can help you ensure that you’re properly balancing your soil and providing the proper maintenance to any crops or plants.

4. What is soil pH?

Throughout this article, you’re likely to hear pH talked about quite a few times.

Soil pH is a measurement of how acidic or alkaline the soil is measured on a scale of 1 to 14.

A measurement of 7.0 is considered neutral while below 7 is acidic and above 7 is alkaline.

Most plants prefer neutral soil between 6.2 and 7.2.

That said, some plants prefer more acidic soil.

5. What does a basic soil analysis provide information about?

A basic soil analysis provides information on two important soil characteristics: soil pH and available nutrient levels.

bulletSoil pH: This is a measurement on a scale from acid (low pH) to alkaline (high pH).

While most soils are on the acid side of the pH spectrum, the best soils are often moderately acidic.

Doing soil sample testing can help to indicate pH problems and allow recommendations for correcting them.

bulletAvailable nutrient levels: these levels in your soil help to determine how good crop growth will be.

Soil sample testing evaluates for phosphorus, potassium, calcium, and magnesium.

By knowing what’s in your soil and whether there are necessary amendments, you can purchase the right fertilizer formulations for the crop to be grown.

6. Do you need more in-depth soil sample testing?

Above, we discuss what information a basic soil analysis tells you.

However, there are more specialized soil sample tests that can help you investigate other factors that may be limiting crop growth.

These include tests for:

bulletSoil salinity: Salinity can build up in coastal areas, soil that is irrigated with brackish water, or soil that has had too much fertilizer applied.

bulletNitrogen: Nitrogen is essential in large quantities for most crops and as such is a basic part of most fertilizer programs.

The test for nitrogen is only useful in certain circumstances.

bulletOrganic carbon: Just like nitrogen, the test for organic carbon is only useful in certain circumstances.

That said, most soils will benefit from the addition of organic matter.

bulletAluminum: If the pH is too low, and aluminum is too available to plants in soil, then this combination can be toxic.

Testing for aluminum levels can reveal issues in soil composition.

bulletMicronutrient: You may analyze micronutrient levels if crop symptoms suggest there is an issue.

Examples of micronutrients include boron, copper, manganese, and zinc.

7. What equipment do you need for soil sample testing?

Soil sample testing only requires a few basic tools.

Here’s what you’ll need for your testing:

bulletMap: If you are taking more than one sample in the area, make sure you have a map that you can use to mark where you took the sample from.

bulletSpade: Use a spade, soil probe or shovel (depending on the test) to collect your sample.

Specialized soil sample testing requires tools made of steel because tools made of brass, bronze, or galvanized metal may contaminate samples with copper or zinc.

bulletPlastic bucket: You should have either a clean plastic bucket or a large plastic bag for collecting and mixing subsamples.

bulletPlastic bag: The plastic bag will contain about 2 cups (1 pint) of the final, composite soil sample.

Keep in mind that it’s better to have thin plastic bags that can “breathe.”

For example, sandwich bags are better than thick plastic bags for storing soil or brown paper bags that can contaminate samples that are being tested for boron.

bulletWaterproof marker: You’ll use this to label the plastic bag so you can identify the sample

8. What is the soil sample testing method?

 Here’s the method you should use for soil sampling.

bulletClear the surface of plant growth from the sample spot

bulletDig a hole about as wide as your spade and as deep as the layer you are sampling

    1. The top 4 inches for lawns, turf, established pasture, and “no-till” fields
    2. The top 8 inches for conventionally tilled fields and garden plots
    3. The top 8 inches plus a separate sample for the 8–24-inch zone for tree crops

bulletUse the spade tip to cut down and remove a slice of one side of the hole wall

bulletKeep the slice on the blade of the spade and use a trowel, knife, or stick to cut away the sides of the slice

bulletLeave a center section about 1 inch wide which will serve as your subsample

bulletPlace the subsamples in the plastic container, mixing well

bulletRemove about 2 cups (1 pint) of this mixture

    • This is your composite sample to send to the laboratory for analysis

9. How often should you do soil sample testing?

While most landowners will start doing soil sample testing when they notice a big issue with their soil, keep in mind that there doesn’t need to be an issue with your crops, plants, or soil for you to act.

In fact, soil tests are often free or low cost through your local county extension office.

As a result, it’s smart to do soil sample testing as often as every 2 to 3 years so that you can ensure you’re caring for your soil and optimizing its health.

Soil under more intensive cultivation may require annual testing.

If you’ve tested the soil in any given area previously, then you should try to do it at the same time as previous years.

10. When should you test the soil?

Soil tests can be done at any time of the year.

However, autumn is the preferred season if you have the option.

Additionally, you should avoid testing the soil when it’s wet or if it’s been fertilized recently.

11. What information needs to accompany the samples?

When submitting your samples for soil sample testing, here’s the information you’ll need to provide in addition to the samples.

For cultivated crops:

bulletSoil name and map symbol from soil survey

bulletTillage depth

bulletPast crops

bulletFuture crops to be grown

bulletCover crops

bulletManure rates, if applied

For gardens, lawns, and trees:

bulletSite characteristics

bulletCrop to be grown

bulletAge of crop

bulletFertilizer used

bulletManure rates applied

You’ll also need to send in your sample depth.

12. How long will it take to get the results of your soil sample testing?

The results will vary depending on where you send your soil samples.

However, as a benchmark, pH tests can take anywhere from 1 to 3 days, and complete nutrient tests take about 1-2 weeks.

13. If you want to do your own soil sample testing, where can you get a test kit?

Standard soil test kits are often available for purchase from county offices, commercial firms, or garden centers that stock kits for the convenience of their customers.

The test kit will often consist of a sample submission form, instructions on how to take a soil sample, a sample bag, and the return envelope to mail the sample back to the laboratory for testing.

14. How do you interpret the soil lab testing and results?

When you submit your soil for soil sample testing, you will receive your results back, which may include interpretations or recommendations from the lab.

When reviewing these, make sure you know what extraction method was used and how the results were reported.

Keep in mind that the lab may report results in parts per million (ppm) or lb/acre.

Here are the conversions:

bulletTo convert ppm to lb/acre, multiply ppm by 2 (lb/acre = ppm x 2).

bulletTo convert lb/acre to ppm, divide lb/acre by 2 (ppm = lb/acre ÷ 2).

15. What are some easy DIY soil tests you can do at home?

bulletThe Squeeze Test

This test helps you determine whether you have clay, sandy, or loamy soil.

Take a handful of moist (but not wet) soil from your garden and give it a firm squeeze.

If it holds its shape and then crumbles when you give it a light poke, then it’s loamy!

If it holds its shape and then sits stubbornly when you give it a light poke, it means it’s clay.

If it falls apart as soon as you open your hand, then it’s sandy soil!

bulletThe Percolation Test

This test will tell you whether you have drainage issues or not.

Dig a hole about six inches wide and one foot deep.

Fill the hole with water and let it drain completely. Repeat.

Keep track of how long it takes for the water to drain.

If it takes more than four hours to drain, then your soil has poor drainage.

bulletThe Worm Test

Having worms in your soil is a positive indicator of overall biological health.

Do the worm test by ensuring that the soil is warmed to at least 55 degrees.

It should also be moist but not soaking wet.

Then, dig a hole one foot across and one foot deep.

Place the soil on a tarp or piece of cardboard.

Then, sift the soil with your hands as you place it back into the hole and count the earthworms that you find.

If you find at least 10 worms, then count the test a success!

bulletThe pH Test

This test is aligned with the soil sample testing we’ve been talking about throughout this article.

To do this test, you’ll need to find a pH test kit at your local home and garden center.

After you’ve followed the provided instructions, you’ll need to send the soil into a lab for them to test.

These tests are one of the best ways to ensure that your soil is the foundation that your plants/crops need it to be!

16. How do you test soil for building construction?

There are numerous types of soil testing that you should do before starting construction.

However, the primary one is a geotechnical study.

The design of the foundation will be based on this soil test report.

Depending on the local requirements and what you are looking to build, the geotechnical study may include the following tests:

bulletMoisture Content Test

bulletSpecific Gravity Test

bulletDry Density Test

bulletAtterberg Limits Test

bulletProctor’s Compaction Test

17. How do you improve acidic or alkaline soil?

You’ll find naturally acidic soil in the Eastern U.S., Alaska, Hawaii, and parts of the Pacific Northwest.

Acidic soil is a good environment for thatch, weeds, and disease and may reduce the effectiveness of your fertilizer or herbicide.

To reduce soil acidity, try garden lime or limestone.

Lime is a natural source of calcium and magnesium and elements necessary for healthy plant growth.

It will take time to correct this problem, so have patience!

Start in the fall for best results.

You’ll find naturally alkaline soils in most of the Central and Southwestern U.S.

These are generally areas with less rainfall.

Alkaline soil often restricts a plant’s ability to take in nutrients, and thus sulfur is recommended.

That said, sphagnum peat moss is an organic and cost-effective alternative that you may also want to consider. 

Final thoughts

There you have it!

Most people don’t realize how essential soil is when it comes to landowning, construction, vegetable gardening, farming, and so much more.

If you’re not getting what you want out of your land right now, don’t hesitate to dig a little deeper (no pun intended!) with soil sample testing.

Your soil could be the root cause of all your issues and getting to the bottom of it may help you grow bigger and better crops/plants.

Additional Resources

If you are looking to buy affordable land, you can check out our Listings page. one-dollar-buy-landAnd before you buy land, make sure you check out Gokce Land Due Diligence Program. gokce-land-due-diligence-program-banner If you are looking to sell land, visit our page on how to Sell Your Land.

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Disclaimer: we are not lawyers, accountants or financial advisors and the information in this article is for informational purposes only. This article is based on our own research and experience and we do our best to keep it accurate and up-to-date, but it may contain errors. Please be sure to consult a legal or financial professional before making any investment decisions.

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