Protecting both the land and the water is a primary focus of the Illinois River Watershed Partnership and we work to educate our community on ways to make a positive difference so that our natural resources are around for future generations to enjoy.  So let’s talk about dirt…


Soil Info Graphic

Understanding Soil Infographic

Photo: The Denver Post,


It’s the foundation of our civilizations, the stuff you never see, a zoo of microorganisms that work to decompose and rebuild and is an integral part of our delicate ecosystem…dirt, or to be more autonomous, soils. We (humans) need soils, plants and animals need soils, earth needs soils, in fact, a large amount of our fresh water is moving through our soils in underwater rivers called aquifers, providing and preserving our fresh water supply!

Soil is the thin layer of “skin” covering the earth’s surface, and is mostly comprised of minerals, degraded rock, organic materials, water, air and many small microorganisms. It is also a non-renewable resource, as it can take hundreds, if not thousands, of years to regenerate just 1” of fertile topsoil!

There are different types of soils as well, fourteen soil classes to be more specific, all comprised of sand, silt and clay. Soils can range from dark, rich chocolate cake-colored loam, to orange sticky clay. Silty loams and sandy soils will absorb water at a faster rate than clay soils, which are the slowest to infiltrate rainfall.

Soil Water Movement

Water moves differently through different soil types

Find out what your soil profile is by doing this simple test, called the Ribbon Test.


Soil Horizons are the profile of the layers of soil on earth. The top layer is the surface litter layer. It includes leaves, branches and other organic rotting matter. Beneath that layer is our very precious topsoil, which consists of the matter and microorganisms needed to grow plants and sustain life.

The next layer down is the subsoil, mostly crumbling rock, sand, clay, gravel and silt. Below that is the parent material layer, which in our area is usually the bedrock. The distance of each layer varies greatly too, depending on your geographic location.

Soils can move along the surface too, caused either by nature or by people. Landslides are one example of how large amounts of soil move across the terrain naturally. If soils are stripped of their plant layer or over-grazed by cattle it can erode and ends up in our waterways as sediment.

Sediment is the number one pollutant to our nation’s waterways according to the U.S. Environmental Protection Agency! It travels through stormwater and can be detrimental to our aquatic ecosystems. Construction site runoff and applied chemicals such as fertilizers and pesticides can also be in stormwater runoff.


Silt Fence Construction sites can use Best Management Practices (BMPs) to contain loose soils and

reduce sediment in stormwater runoff.

Photo: Erosion Control Specialists, Inc.


We can do many things to preserve and protect our soils and reduce stormwater pollutants:

- Plant trees along riparian zones of streams, rivers and lakes!

- Plant native plants for their deep root systems and soil benefits!

- Compost and add organic layers to soil to build new soil!

- Participate in Best Management Practices such as using appropriate silt fencing around construction sites.

- Be mindful in use of fertilizers and pesticides, or avoid all together!

- Utilize our local Natural Resources Conservation Services programs such as EQIP to restore and protect agricultural lands, especially streamside!

- Carefully plan urban growth and development.



Amsel, Sheri. “Ecology.” The Dirt on Dirt — Why is Soil Important?. Exploring Nature Educational Resource. © 2005 – 2014. January 20, 2014.


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