Activities for the Season - Physical Tests

Soil is made up of particles of rock that have broken down over time.  These particles vary in size and soil scientists have classified these particles according to their sizes.  Sand particles are the largest particles, silt are the middle size, and clay is the smallest. 

Soil structure refers to the way different sizes of soil particles (sand, silt, and clay) are clumped together into what soil scientists call aggregates.  It is within the spaces between these aggregates that both air and water get into the soil.  These spaces are also where tiny living things such as plant roots, microorganisms, insects, and fungal hyphae are found.  

Compaction is a characteristic of soil that describes how tightly the spaces in the soil are packed together.  Soils that are highly compacted have fewer spaces for air, water, and living things.   Percolation describes the movement of water through the soil.  Percolation is another measure of the amount of compaction of your soil. 

Creating a mudshake helps you to see the different layers present in your soil sample. Texture refers to the different sizes of particles in the soil and the percentages of each in your sample.  By observing and feeling the soil you can make an educated guess as to whether it is mostly sand, silt, or clay.