Watch this video first
Let’s start with a great video that helps us understand the importance of soil. Click here to view the “How Dirt Works” video by Nature Works Everywhere.
A Little About Soil
Soil is a valuable natural resource that regulates water, filters pollutants, sustains plant and animal life, cycles nutrients, and supports structures. Because of these attributes, it’s able to sustain life on earth.
Soil is made from 4 things:
- rock that has been broken down by weather and biological activity (mineral component)
- organic matter (decomposing plants and animals)
- water (in wet environments, there is more water in the soil)
- air (in dry environments, there is more air in the soil)
Although this 4-part cocktail seems simple, it takes 500 years for natural processes to make it.
The mineral component of soil consists of 3 classifications: sand, silt, and clay.
- Sand particles are the largest in soil (2.0 – 0.05mm), are easily visible to the naked eye, feel gritty to touch, and do not retain water.
- Silt particles range from 0.05 – 0.002mm in diameter, feel like flour to touch, and hold minerals well. Due to particle size, silty soils hold more water than sand but less than clay.
- Clay particles are the smallest (less than 0.002mm), feel sticky when wet, and holds water for long periods of time.
Loam is a term used to describe highly productive soils that consist of 40% sand, 40% silt, and 20% clay. You can easily test the soil in your garden to see how closely it resembles loam.
This is a great activity for kids and easy for you to plan!
How to Conduct a Soil Composition Analysis for your Garden
- glass jar or similar container
- trowel (small shovel)
- Find a good spot to dig up soil – make sure the top layer of organic matter is scraped away and try to dig down, not out
- Fill you jar half way with soil. Notice the color of the soil and compare it to this guide on soil colors.
- Fill the rest of the jar with water, leaving a little space for air
- Put a lid on the jar and shake well
- Let the jar sit on your counter without being disturbed for a few days
- Measurement – you can use relative measurement and eye-ball the differences or you can measure the layers and assign percentages. (Remember – part divided by whole! Measure the width of the each layer and divide that number by the total height of the soil sample.) See the video below for help.
Click here to watch a video of someone conducting their own soil composition analysis. *Note that he used the term loam to describe the silt layer; however, our definition of loam includes all 3 mineral components of soil in their appropriate proportions.