Most of us think that soil is just a lifeless mass of minerals. Actually, soils are very much alive with macro and micro-organisms.
Macro-organisms can be such things as earthworms, slugs, snails and ants. Earthworms burrow through the soil producing air space, especially important in Colorado's heavy clay soils for good root growth.
Materials eaten by earthworms passes through their bodies and are excreted in a form known as earthworm casts. The casts, as compared to the original soil, are higher in nitrogen, organic matter, magnesium and available phosphorus. Earthwork casts can weigh up to 360 pounds per 1,000 square feet of soil. The actual weight of worms can range from 2 to 22 pounds for the same-sized area
Microorganisms are very small and include algae and fungi. There can be billions of microorganisms in a teaspoon of soil and they can weigh up to 5-10 tons per acre of soil.
Photo: Judy Sedbrook
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010