Testing Your Soil pH



Soil is the most important aspect when it comes to successful gardening. How well your plant thrives depends on the quality of the soil, and this encompasses the fertility and texture. Fertility involves the amount of nutrients and the level of pH within the soil that facilitates availability of these nutrients to the plants. This article will touch on how you can test your soil for its pH level with a do-it-yourself test kit.

The level of pH in soil

The pH on a soil shows its acidity or alkalinity. pH range from 1.0 to 14.0, with a value of below 7.0 being acidic (lowest being most acidic) and above 7.0 being alkaline (highest being most alkaline). Certain nutrients are only available to plants at certain range of pH. Depending on what type of plants you have, some prefer a pH in the low acid to neutral range (6.2 – 6.8), while others prefer alkaline soil (such as lilacs and clematis). Altering the soil pH to the level that you want for your plant takes time, so you may need to repeat the treatment until the desired pH is obtained.

To reduce the alkalinity, amend the soil with a sulfur product, iron sulfates, aluminum sulfate, peat moss or evergreen needles. These tend to lower the pH of soil. Plants such as azaleas, rhododendrons and blueberries prefer acidic soil. To increase the pH (make it more alkaline), use agricultural line, quicklime or slaked lime (the later two being very caustic and should no be applied directly to soil).

Below is a table of plants and their pH of preference

Very strongly acid soil 4.5-5.0

Blueberry, orchid, azalea, for blue hydrangea (less acidic for pink), bilberry, cranberry, sweet gum, pin oak.

Strongly acid soil pH 5.0 – 5.5

Parsley, heather, conifers, pine, sweet potato, potato, tomato, maize, millet, oars, tye, radish, rhododendron, camellia, ferns, iris, orchids, daphne and boronia.

Moderately acid soil pH 5.5 – 6.0

Bean, brussels sprouts, carrot, choko, endive, canna, daffodil, jonquil, larkspur, petunia, kohl rabi, peanuts, rhubarb, soyabean, crimson clover, aster, begonia, primrose, violet and majority of bulbs.

Slightly acid soil. pH 6.0 – 6.5

Broccoli, pea, sweet corn, pumpkin, squash, cabbage, cauliflower, cucumber, egg plant, turnip, gladiolus, iceland poppy, pansy, rose, red clover, sweet clover, white clover, candytuft, Zinnea, snapdragon, Viola, Wallflower and Strawberry.

Very mildly acid soil pH 6.5 – 7.0

Asparagus, lettuce, melons, onion, parsnip, spinach, beet, celery, dahlia, lucerne, carnation, chrysanthemum, stock, sweet pea and tulip.

ph test results

ph test results

Sampling soil for tests

Where to Sample Soil

When you take a sample of soil for testing, the depth where upon the sample is taken from is an important factor. Take samples from tillage depth, because this is where the majority of soil nutrients is found. The timing of your sampling is also important because various nutrients are present in soil at various times of the year. The best time to attain a sample is in the fall after harvesting, although this isn\’t the only time you need to bind yourself to gain a sample.

When to Sample Soil

Once you\’ve obtained a sample of soil, you need to analyze the soil as soon as possible. If it cannot be analyzed within 24 hours, then the sample should be frozen. Freezing the sample will reduce changes in the soil due to biological and chemical activity. Any period of time longer requires air drying of the soil sample, which will stabilize the soil for periods of 6 months or more.

Performing the Test

You can test the pH of the soil by purchasing a DIY test kit which is available in a garden center. Follow the instructions on the kit precisely to gain an accurate reading. They can also be bought through universities or private labs. Prices may vary according to place of purchase. Some university and agricultural department even offer free soil test (which also includes nutrient, composition and other tests). Find out more about your options at your local universities and agricultural departments.

With a shovel, trowel or bulb digger, obtain 3 feet by 3 feet soil sample that is Dig six to eight inches deep from the surface level. You may need to obtain more than just one sample if you have a larger size of the area in the garden (especially if the lot is bigger than 10 feet by 10 feet). Place the samples in sealable bags and label them accordingly. Do not mix these samples together.

Testing the Soil

  1. Lay out a sample of soil on a piece of paper and remove any leaves, sticks or stones. Crush any lumps of soil with a plastic spoon and allow the soil to dry overnight.
  2. If you have purchased a test kit, fill the included test tub with distilled water and drop the test tablet.
  3. Add about one cap of soil.
  4. Close the test tube with its lid and invert the tube to mix the soil and chemicals together.
  5. Allow the tube to stand for about a minute before you do your reading.
  6. Hold the test tube next to the color chart included in the soil testing kit to test for pH.
  7. Red water denotes a 4.0 pH, orange for 5.0, yellow for 6.0, light green for 7.0, dark green for 8.0 and purple for 9.0.

Note: Once you\’re done with your testing, pour the test water down a drain with lots of running water. Make sure that you dispose of treated soil samples in a proper manner.

Amend the soil as needed once you\’ve done the test to correct the soil to your plant requirement. If you find that your plant is still struggling with growth, contact the local cooperative service that will be able to help you test your soil in a lab and advise you on any other mineral deficiencies that you will need to amend.

It is important to learn as much as you can about the soil you have in your garden, as this will help you decide what you need to do to make it ideal for plant growth. Knowing your soil\’s pH level will help avoid disappointing results and help your plants thrive in your garden.

More Reading:


Soil pH: http://en.wikipedia.org/wiki/Soil_pH