DIY Soil Science: Analyzing Soil Composition with Mason Jars

Picture
by London Permaculture / Flickr
​If you're a new gardener, you’ve probably heard a lot of talk about good and bad soil and are wondering if the soil in your garden is good for growing vegetables.  Soil consists of three main components: clay, sand, and silt.

​For optimal gardening results, you will want loamy soil. 
​

What is Loamy Soil?


Perdue University says loamy soil contains approximately equal amounts of clay, sand, and silt. Others quote a ratio of 40% sand, 40% silt, and 20% clay as ideal for most garden vegetables. 
​

How do you know what type of soil you have?


​​It isn’t always easy to determine your soil type by look or feel. This quick and easy Mason jar test will give you a good idea of the composition of your soil. 

​ How to Use Mason Jars for Composition Analysis


  1. Gather a cup or two of soil from your garden area. Remove any large rocks, portions of roots, or any other debris from the soil
  2. Fill a quart mason (or other straight-sided jar) jar approximately halfway with your soil sample.
  3. Pour water into the jar to within an inch or two of the rim. Replace the cover and seal tightly.
  4. Shake the jar vigorously for several minutes to mix the soil and water
  5. Place the jar on a flat surface, such as the table, and allow the sediment to settle for one minute. Sand particles will settle quickly. Mark the level of sand particles on the side of the jar with a permanent marker. Use care not to disturb or move the jar.
  6. Allow the jar to sit undisturbed for another hour. Silt will settle over the top of the sand layer. Mark the height of the silt on the side of the jar.
  7. Leave the jar in the same location for 24 hours and mark the third layer, which is composed of clay.
  8. Measure the height of each layer of soil (sand, silt, and clay) as well as the overall height of the soil in the jar. To determine the percentage of each layer, divide the height of each individual layer by the total height of the soil in the jar.
  9. Note the percentage of each soil component on the outside edge of the chart to the right and draw intersecting lines to the center to determine the makeup of your soil.
Ideal Garden Soil
40% Silt
40% Sand
20% Clay
Mastering the Math: Calculating Percentages with Ease

​Height of Layer ÷ Total Height of Soil
Don't worry if the sand, silt, and clay percentages in your soil aren't perfectly balanced. Most vegetables will thrive as long as your soil is classified as loam. However, be cautious if your soil falls into the extreme outer edges of the chart.