What is soil made of and how does it help trees, flowers, and plants?

(Lansing State Journal, Jan.15 1997)

Soil is made up of minerals and organic matter. The mineral part of the soil is actually rocks that have been broken down by weathering. Weathering occurs after many years of exposure to elements like wind and rain, high and freezing temperatures, and river and glacier movement. The organic part of the soil is made up of decayed plants and micro-organisms.

The formation of soil takes a long time. First, the rock is broken down and chemical changes take place when the minerals come in contact with the air and water. Then plants help the soil building process. When the plants die and decay, bacteria live on the decayed matter and leave organic compounds in the soil. New plants use these compounds as food.

Soil is the storehouse which contains the chemicals that people, trees, plants, animals, and flowers need to grow. Humans do not get these nutrients directly from the soil. Plants draw the nutrients from the soil and change them into food we can use. People eat the plants, or animals eat the plants and then we eat the animals.

Back to MSU Science Theatre Home Page