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How to Use & Interpret Your Soil Tests

soil meter in a garden ted lare design & build

Soil is the foundation for a healthy yard, in more ways than one. It’s more than what we walk on. Soil should provide our plants with nutrients, hold just the right amount of water that our plants will need, and encourage them to put out root systems. Similar to how we need food and water to survive, our plants and trees do too, and the soil should provide much of this for them.

If your plants are struggling, or they’re just lackluster and never seem to grow, there are a few things to check, like whether it’s planted in a location suited to its preferences. But, if your plants, shrubs, and trees are all planted where they should get the right amount of sunlight, then you might want to move on to checking the soil.

Besides making sure your soil has enough organic matter to hold onto a bit of moisture and some larger textures to help it drain well, you should also check the nutrient profiles.

You can use a soil test kit to test the soil in your yard and determine if your soil might be causing your less-than-stellar growth, and figure out what you can do to improve the soil for your plants, trees, and shrubs.

Soil test kits usually consist of four test tubes and different chemical reaction additives for testing. It is best to use distilled water for your tests to ensure there are no water treatment chemicals or minerals that could affect your interpretation. 

You can get soil test kits that just test the pH of your soil, but it’s worth getting one that tests for nitrogen, phosphorus, and potassium (NPK) as well.

soil test kit in garden ted lare design & build

How to Use Your Soil Test Kit

Carefully read the instruction guide included with your soil test kit before you start. For the pH test, you can usually do it quite quickly with just a tiny bit of soil, distilled water, and the powder capsule. 

For the NPK soil tests, it’s best to collect soil samples from a few different locations around your yard, create a mixture of all the soils with distilled water, and then wait for it to settle. A mixture of 1 part soil to 1 part distilled water will give you a good sample.

Before you start, think about which plants you want a soil test interpretation for. Perennials, shrubs, and trees all have deep roots. So if you’re going to test the soil from them, you’ll need to get samples from 12-16 inches deep. If you just want to make sure your annuals do well, you can just test surface soil, from 3-5 inches deep.

Mix your soil test samples in a jar, add distilled water, close it tightly, and then shake it for at least 1 full minute, then set it aside to settle. Settling could take anywhere from 30 minutes to 24 hours, depending on your local soil. Ideally, the water should be as clear as possible before testing.

The exciting thing about this soil test mixture is that you’ll also be able to see what makes up your soil as it settles in layers in the jar. This interpretation can help you determine if your soil needs more coarse material added to improve drainage or more organic matter to improve moisture retention.

Follow the instructions in the guide closely. Usually, you’ll use a dropper to fill a soil test tube with water from your jar to a specific line, and then add the powder from one of the capsules. Give it a good shake, and then let it sit for about 10 minutes. Then compare the color of the soil to the chart included in your kit.

The color chart will tell you how high the levels of each nutrient are in your soil.

person testing soil in planter ted lare design & build

Soil Test Interpretation

The color chart gives you a good guide of your current nutrient levels, but the interpretation of how to amend your soil to fix nutrient deficiencies can be more complex. Read all the information in the kit carefully, and mark your soil test results down somewhere before you dump out your samples. Even better, take a picture of each test tube next to the interpretation chart and keep them on your phone or computer. 

Once you know your levels, you’ll need to do a bit of research to figure out the best way to solve any soil deficiencies you might have. If you have low nutrient levels, there are different products you can add to your soil to build up its health and nutrient balance over time. 

If you have low nitrogen, you can add well-composted manure, grass clippings, coffee grounds, grow a green manure cover crop, add a fish emulsion, or use nitrogen fertilizer, although that is not a long term solution. If you’re low in phosphorus, you can use a phosphorus fertilizer, but be careful not to use too much since phosphorus doesn’t get used up or break down the same way other minerals do. If you have low potassium, you can add actual potash or your own compost. Compost from fruits, veggies, and green yard material is an excellent source of potassium. Banana peels in particular are high in potassium, so add them to your compost bin. 

If some of the nutrient levels in your soil are too high, it’s a bit more complicated to deal with, and you should seek the advice of your local extension office. You may want to consider having a soil analysis done by an actual lab. The extension office will be able to guide your soil amendment strategy.

If you’d like to test your soil this year, stop by Ted Lare and pick up a test kit. If you’re not sure how to amend your soil after getting your test results, have a chat with one of our experts for some advice on how to improve your soil for healthier plants. 


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