How Much Heat Does Soil Absorb?

Soil Components

• Soil components range in size, beginning with clay that is created when minerals and organic matter are ground into tiny microscopic particles, which gives clay a smooth, slippery texture. Silt is the next smallest, consisting of fine particles just larger than clay. Sand is familiar from sandy beaches or a child's sandbox. Sand is small pieces of minerals, usually including quartz. Tiny to small rocks are called gravel, the largest soil particle.

Organic Matter

• Soils contain varying amounts of organic matter which come from dead organisms. Environments where there are lots of plants and animals have soils that contain more organic matter. Compare mountain soil to sandy desert soil. Not all of the dead matter is ground up fine to be part of the clay component; much of it is larger pieces. Organic matter holds water and does not absorb heat well, so organic mulching keeps soil cool and damp.

Soil Water

• Different soil mixes can hold different amounts of water. Soil with a high gravel and sand content has high porosity. Porosity can be thought of as the amount of air pockets in the soil. Water flows through gravelly or sandy soils but is held by dense soils that have lots of clay, silt and organics. The tiny clay and silt particles stick to each other, eliminating air pockets. Wet soil absorbs heat more slowly.

Heat Absorption

• Soil with the highest amount of sand in it will absorb more heat than soil with a lot of organic matter, silt or clay. A barefoot walk across a sandy beach on a hot day illustrates this. Sand has lots of quartz and other heat absorbing minerals in it while a mountain path has lots of clay, silt and organic matter. The mountain path is cool, and the dry sand is hot.