How to test your soil

Testing your soil is important if you want to know what nutrients are lacking that could help your plants perform better. It is quick, easy and inexpensive to test the soil yourself.

If you are an avid gardener or simply someone who wants to plant things in your yard and have them be successful, you've probably wondered what exactly is in your soil and how you could make the soil better for your plants.

It is easy to find out the basic nutrient components of your soil through the use of at-home soil test kits. You could also send a soil sample to your local or county Cooperative Extension Service, which will get you a much more detailed and scientific look at what's in your soil, but for most home gardeners the test kits you can find at many hardware and garden supply stores are sufficient.

Before we talk about the actual testing process, it is important to know what exactly you are testing for and why these things are important to the health of your plants. A basic test kit will include tests for nitrogen, phosphorus, potassium and Ph. (A test done by a county agent or a commercial lab might also include tests for such things as calcium, magnesium, lime, iron and saturation levels.)

Nitrogen is the nutrient that plants need the most of. It is a necessary part of all proteins and helps with energy transfer. It's also a building block of chlorophyll, the compound that makes plants green. Having a good amount of nitrogen helps plants grow faster, produce more fruit and have healthier greenery. Phosphorus is also important in photosynthesis and helps the plant grow faster and have stronger roots and more blooms. Potassium helps keep plants healthy, makes them set higher-quality fruit and helps build protein.

Ph has to do with the amount of acid in your soil and the amount that you'll want depends on the foods or plants you are growing. Azaleas, tomatoes and many other plants like a high-acid soil, though a range of 6 to 6.5 is ideal for making other nutrients available to plants through the soil.

Your basic test kit will include four plastic containers (one for each test) some kind of pill or vial containing a powder that is used in each soil test (often these come in capsules that are different colors, corresponding to the lids of each plastic test vial) and instructions.



For each test you will need a small sample of soil. If you want to test your whole garden patch you can take samples from several places and mix them together. If you are testing soil for a garden, you will want to take your sample from a depth of six to eight inches (where the roots are) but if you are testing a lawn your sample should come from about three inches deep.

Follow the instructions that come with your test kit. Some tests will ask you to put the soil directly into the test cup, while others will want the soil to have been mixed with water and allowed to sit before the water itself is tested. Many Ph tests ask for this step, and if yours does you'll probably want to do a Ph test on your water first so you can compare the two and consider how the Ph of the water will affect whatever amendments you add to the soil.

These tests will take less than a half an hour to complete. You add the soil and water or the watery soil mixture to the vial in the amount specified (there's usually a fill line on the side of the container) and then add the testing powder. Put the lid on the vial and shake gently to dissolve the testing powder. Allow to site for the specified time and compare the color of the water in the vial to the color chart in the instructions, which will help you determine the amount of each nutrient in the soil and whether it is high or low.

If your soil is high in a nutrient, there is not much to do, just know that you do not need to add any more of that nutrient until it tests lower (you should test your soil at least once a year, and ideally both spring and fall). If your soil is deficient in a nutrient, you can amend the soil with chemical fertilizer or organic fertilizers. The numbers on the bag such as 15-15-10, indicate the percentage of each nutrient is in the concoction, nitrogen, phosphorus and potassium. So the above example would include 15 percent nitrogen, 15 percent phosphorus and 10 percent potassium. The rest of the fertilizer is made of other minerals and nutrients, which may or may not be specifically listed on the package.

Ph can be adjusted by adding lime to raise the Ph (making it more acidic) or elemental sulfur to lower the Ph (more alkaline). Adding sulfur can be quite expensive but is necessary in parts of the country where the soil is naturally very acidic.

It is best to apply fertilizer at least a few weeks before planting in the spring because the nutrients themselves often are too strong to be in contact with seeds or gentle roots. If you have a tiller, you can till in the nutrients and water well, allowing the spot to lie dormant for a few weeks before planting.

Keeping tabs on and adjusting the nutrient levels in your soil is very important for the health of your plants, particularly if you are growing vegetables and fruit to eat. It is easy, quick and inexpensive to test the soil yourself, and the results can be very helpful in improving the quality of your soil and the fruits of that soil.

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