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Soil Testing and pH

10 years ago

A good lawn and garden begins with good soil. The best way to find out the condition of your soil is to contact a local County Extension office and get a soil test done. These are in most states but there are exceptions, CA and OR being two. In this case you can usually find a private lab listed in your Yellow Pages, on the Web or get a referral from a University or Garden Center.

They are generally quite inexpensive for a basic evaluation (less than $10). You can get home test kits but the feeling is that the lab tests are more reliable.

A soil test will help determine what your native soil is so you can select plants that will do well on your land. In most cases the lab will make recommendations for amendments you can add to alter the characteristics of your soil for optimal plant growth.

Having your soil tested allows you to determine the best plants for your garden and gives you a baseline for improving it depending on the type of plants you wish to grow.

Testing on a regular basis allows you to monitor the available nutrient, nitrogen, phosphorous and potassium and add what is needed for optimal plant growth and vigor.

The best time to test your soil is in late fall or early spring. This gives the soil microbes time to adjust to, and incorporate the corrections.

The Testing Process

Most of the labs will send you the details on how they want you to collect samples but they are basically similar to this.

Gather together:

  • A Clean Bucket
  • A Clean Trowel
  • A Clean 1 Qt container for the sample

Collect The Sample

  1. Dig a number of holes 6-8 inches deep in the area you wish to test.

  2. Take a thin slice from the wall of the hole and place it in the bucket.

  3. Repeat for each of the holes you dug.

  4. Thoroughly mix all the soil together.

  5. If the soil is very wet spread it out on some newspaper to let it dry a bit. It is important to have a dry sample. If the sample is too wet it can give false results.

  6. Place some of the collected soil in the container and seal. Mark the bag with your name, address, and date.



The testing agency can give you specific recommendations on amounts of material you need to add to get the desired results.

  • Alkaline Soil-pH above 7.0 pH too low--Adding sulfur will lower the pH

  • Acidic Soil-pH below 7.0 pH too high--Adding lime will raise pH

  • Poor Nitrogen Content Addition of fertilizers Natural (preferred) or synthetic will increase the soils nitrogen content.

  • Nitrogen Levels Too High It is possible to have soil that is too rich. Too reduce the nitrogen content water well and often and add no additional fertilizer till levels are reduced.

  • Low Phosphorus Levels Bone meal or super phosphate will bring up the phosphorus levels.

  • Phosphorus Level Too High Use a fertilizer that is lower in phosphorus and plant densely to use up the excess.

  • Low Potassium Level Add potash to raise the potassium

  • High Potassium Levals Add no additional potassium till levels are reduced.

Side Note Gardeners who practice Organic methods have often found chemical additions to be a temporary fix. It has been shown that the addition of vegetative matter, in the form of compost, worked into the soil every year will usually have the effect of leveling out chemical unbalances. This often will have a much more permanent and positive effect.

Improving Soil Texture/Drainage (Tilth)

Soil falls into a number of categories. Clay, sand, loam, and many combinations. Each has distinct characteristics. Poor draining, unable to retain nutrients, dense and hard to plant in or work.

In most cases the addition of organic materials will improve the condition of whatever type or soil you may have.

A few of the things that are effective are:

  • Compost
  • Peat Moss
  • Leaf Mold
  • Shredded Leaves

Thanks to all who contributed to this piece.


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