How to Test Your Soil With Just a Mason Jar

There is an easy and cost-effective way for you to test the quality of your garden soil at home. All this method requires is a lidded mason jar plus a little bit of background knowledge. Let’s get a basic understanding of some soil properties before describing how to test your soil. 

Understanding Soil Components

Soil is composed of mineral particles, water, air, and dead organic matter. But what you actually see in the soil (we don’t see air, for example, and water may just be absorbed) are different sized particle components. There are three soil particle components: clay, sand, and silt.

Clay is the smallest mineral particle. But since flat, sticky clay particles fit closely together, this type of particle actually produces the largest surface area of all soil components. Clay drains poorly because it retains water so well and is the slowest to warm in the spring.

Silt is the next largest component, made of rock and mineral particles. It has a smooth, floury texture when dry but feels slippery when wet (think of the sediment found at the bottom of a pond).

Sand is the largest soil particle. These gritty particles are round, not flat, which allows water to drain quickly. This also means nutrients drain quickly, so additional watering and fertilizer treatments are necessary with sandy soil.

The Purpose of Testing

The term loam refers to a balanced combination of these three particles: a 20%/40%/40% balance is considered an ideal gardening soil. If your soil has too much sand, this is considered sandy loam. If it has too much clay and sand, it’s considered sandy clay, and so on. A mason jar soil test will identify which, if any, soil particles are predominant. Based on the results, you can add relevant soil amendments.

Test Your Soil With a Mason Jar

1. Ensure your pint- or quart-sized mason jar is clean and still contains a tight lid. If you can no longer find the lid, they are easily available for separate purchase, along with lid rims.
2. Fill half of the jar with your garden soil. Determine whether you want to combine soil from various garden areas/multiple beds for an overall picture or whether you will test each area independently.
3. Fill the jar with water, but leave a little air to shake the mixture.
4. After tightening the lid, shake the jar for several minutes to ensure all particles are suspended in water.
5. Let your jar sit for several hours. You will see the particles begin to separate into clay, silt, and sand layers. If you don’t see clear differentiations between layers, or particles are still settling, leave the jar untouched for 24 hours.

Reading the Results

Read the results of your mason jar by layer. The bottom layer is heavier particles of sand and rocks. The layer on top of sand is silt. Clay particles are the top layer. Remember, you are aiming for a 20% clay, 40% silt, and 40% sand loam mixture. If you have twice as much clay than silt and sand, you have a 50%/25%/25% blend.

Also look at the color of your soil. Lighter soil colors have less organic content that dark soils, which also warm faster in the spring. If your soil is light, consider adding organic matter to your soil before planting your crops. This will give time for the organic matter to decompose prior to planting. Based on this easy test, you now know what amendments you need to add.

Want to learn more about testing your garden soil in a jar?

See these articles for additional information:
Mechanical Analysis of Soils: The Jar Test from Oregon State University Extension
Soil Texturing in a Quart Jar (Soil Hydrometer Test) from Utah State University in the Classroom

Creative Commons Flickr photo courtesy of Gnomedude,  E. Dronkert Stevier and Windell Oskay