There's a lot more to good soil than dirt

“Why is soil texture important?” asked Katherine Crawford's fifth-graders at West Oak Middle School in Mundelein.

Here's the dirt on soil. You might think soil is the dirt you track onto the carpet, but it's not. That's dirt.

Soil is the many-layered material that carries nutrients that bring life to plants, insects, animals and ultimately to humans. It filters toxins from water. It prevents flooding and shores up construction.

Good soil doesn't happen by chance — soil formation, called pedogenesis, develops because of several events and results in a soil life cycle.

Soil layers are called horizons. At the top is topsoil, then subsoil and next is weathered parent material. The foundation of soil is bedrock.

Soil looks simple but has a complex recipe if it's going to be good — a vital mix includes air, water, living and decomposing plants and animals, minerals, fungi, carbon and nitrogen.

Soil has several distinct properties; texture is one of them.

“The importance of soil texture is to determine the water, nutrients, and aeration availability that plants and organisms need for their growth and activities,” said Mahdi Al-Kaisi, associate professor of soil management/environment at Iowa State University.

“Soil texture refers to the percentages of sand, silts, and clay found in soil,” Al-Kaisi said. “These particles are different in size. Sand is the largest in diameter, followed by silts and then clay. Different soils have different portions or percentages of these particles which effect soil properties.”

Al-Kaisi is conducting research that involves the impact of crops on soil and how using corn in biofuels might alter carbon amounts found in soil.

While soil texture generally relates to planting issues, it also serves another important purpose.

“The value of soil texture is very important in determining the strength of soil for road construction and building foundations, because soils with different textures compact differently under pressure,” he said.

The Fremont Public Library District in Mundelein suggests these titles on soil:

Ÿ “Rocks and Soil,” by Steven M. Hoffman

Ÿ “A Handful of Dirt,” by Raymond Bial

Ÿ “Secret Lives of Soil Creatures,” by Sarah Swan Miller

Ÿ “The Rock Cycle,” by Cheryl Jakab