The Why and How-To of Testing Garden Soil

  

  
The health and quality of your soil has a direct effect on everything you grow in your garden. The key elements affecting our soils are physical structure, including the amount of clay content, the pH and soil fertility. Testing your garden soil on a regular basis is important and can be accomplished at home using soil test kits or soil samples can be sent to a testing lab for analysis.  

 

If you decide to test your soil at home, it’s important to include a test that will measure the acid-alkaline balance, known as soil pH level. Soil pH affects the availability of nutrients to vegetable plants, as well as the microbial activity in your soil.  No matter the quality of the fertilizer or supplements you apply, tomato and vegetable plants can’t use them if the pH is too high.  

 

Soil pH is a measure of the acidity or alkalinity of a soil. On the pH scale, 7.0 is neutral, above 7 is alkaline, below 7 is acidic. Bleach for example is very alkaline. Lemon juice is very acidic. Most plants prefer a pH of between 6.5 and 7. Our soil is typically greater than 7.  

 

This soil check kit is an easy and quick way to check the pH levels in your garden.  Home test kits are also available to measure the Nitrogen, Phosphate and Potash levels in your garden beds.  Stop in and let us explain how to use these testers.  

  

Colorado State University also offers soil testing. Follow this link to learn how take and submit a sample for analysis, as well the cost for testing: https://agsci.colostate.edu/soiltestinglab/ 

  

In addition to pH and nutrient levels, the structure, physical makeup, and organic content of your soil has a direct impact on your garden’s productivity. Whether you’re growing in a raised bed or an in-ground one, the quality of the soil affects everything from strong root development to flower and fruit production.  

 

The Jar Test is a quick, easy way to help you determine the structure and physical makeup of your soil.

You’ll need a clean jar with a lid, in this case a peanut butter container. Put 4-5 ounces of soil in the bottom of the jar. Add enough water to fill the jar 2/3 full.  Add a drop or two of dishwasher soap. Put the lid on and shake well, then let the jar sit undisturbed for 24 hours. You’ll see that the soil has settled into layers.  

 

The first layer will be sand. The second layer will be silt, followed by clay, suspended clay, then a small amount of organic material, floating at the top. This is evident in the jar on the left. Typically, you’re going to see a small amount of sand and silt, a large percentage of clay and a small amount of organic material.  

 

As you add more organic material to your garden, your test results will look more like the jar in the middle. The jar on the right illustrates a well-amended garden soil: dark and rich, with more organic material suspended in with the clay.  

 

As a rule, to improve your garden soil and lower the pH, you need to add more organic material in the form of coconut coir, sheep manure and organic compost. We recommend you add two to three inches of locally produced organic material to your garden in the spring and again in the fall.  

  

Whether you test your own soil or use CSU’s lab, bring us the results. We'll recommend the right amendments and fertilizers to make your garden soil healthier and more productive.