How Does Temperature and Light Affect Soil Organisms?

Light

• Most of the heat in the soil comes from the light hitting it sent from the sun. Light makes plant life possible. Plants are able to photosynthesize because of the energy they receive from light. Plants capture carbon from the atmosphere and bind it into organic compounds that serve as food for all other organisms. The more light a soil receives, the denser the plant growth can be. With increased plant growth, there is more food for soil organisms. Even though most soil organisms do not directly need light to survive, they depend on it secondarily for their survival.

Soil Temperature

• Some of the soil's temperature can be accounted for by the geothermal activity underneath it. Since soil is denser than air, it changes temperature much slower. The soil absorbs the heat delivered by light from the sun and stores it. At a depth of 1 foot, the soil temperature is fairly consistent throughout the day. Soil temperatures at this depth do change with the seasons, but below 5 or 6 feet the temperature is consistent year-round. If there is ample moisture, the greater the soil temperature the greater the activity of soil organisms will be. In tropical climates, there are more soil organisms than in cooler, drier areas.

Soil Organisms

• Worms, nematodes, amoebas, insects and many other tiny creatures inhabit the soil. These organisms are very small and millions of them can inhabit a small amount of soil. Soil organisms live off the food chain set off by the sun with photosynthesis in plants. Though increased temperatures and light are beneficial for soil organisms, these are not the only factors that affect them. Water is key to the amount and activity of soil organisms. If there is not enough water, soil organisms will go dormant or die. Soil organisms are vital to the fertility of the soil. Many microorganisms help to trap atmospheric elements, such as nitrogen, that are essential to plants.

Disturbed Soil

• Plowing or digging up a soil exposes it to oxygen and helps to break down organic matter so that it can release nutrients. Oxygen also causes certain beneficial soil organisms to thrive. Disturbing a soil also exposes it to light, which can kill soil organisms. Turning the soil over too often can be detrimental to soil organisms. Worms flee the light from the sun because it dries them out. Disturbing the soil also allows moisture to evaporate more quickly since it increases the surface area of the soil. Disturb the soil as little as possible to preserve healthy soil organisms and ideal moisture conditions.