Watershed Defenders was developed by the Colorado Foundation for Agriculture (www.GrowingYourFuture.com) with support from the Colorado Nonpoint Source Program and Colorado Department of Public Health and Environment, Water Quality Control Division. ©2011 Colorado Foundation for Agriculture.

This edition of Colorado Kids was created by the Colorado Foundation for Agriculture (www.growingyourfuture.com). ©2015 Colorado Foundation for Agriculture.

The Urban LandscapeAll of the Earth is covered in soil, but in cities much of it is covered by buildings, roads and other human-made surfaces. In this context, it’s important to understand soil types and functions so that these structures have a solid foundation. Just as importantly, soils play a role in water filtering, plant growth, animal habitat and flood control.

A park provides a place for a picnic or to play soccer, but it also absorbs and filters rain water and is part of the overall ecosystem we call ‘nature’. Worms, ants, beetles, bacteria and other soil-dwelling organisms are as important in the system as the larger animals.

Urban gardens are an important source of fruits and vegetables. Rain gardens (see page three) assist with reducing pollution by filtering water that runs off hard surfaces such as rooftops, sidewalks and roads. Excessive pollution or other damage can compromise soil’s life-sustaining functions.

UrbanSoils

W H Y

M A T T E RWhat is Soil?Along with water and air, soil is the basis for life on earth. It is a living thing that forms the upper layer of the Earth’s surface. It consists of organic material, clay and rock particles, as well as air and water. It is vital for plant growth, water storage and habitat.

There can be billions of microorganisms—a population greater than the human population on Earth—in a teaspoon of soil.

www.soils.org/IYS

The 2015 International Year of Soils is an international effort to raise awareness and promote the sustainability of our limited soil resources.

What Is Healthy Soil?Soil health has been defined as “the continued capacity of soil to function as a vital living system, within ecosystem and land-use boundaries, to sustain biological productivity, promote the quality of air and water environments, and maintain plant, animal, and human health” (Pankhurst et al., 1997). It’s important to note that this definition includes: » soil is a living thing, » health is measured over time, and » not all soil is the same—the type and location is part of assessing health.

The Carbon CycleYou’ve probably heard of the water cycle. In the water cycle, water evaporates, forms clouds and returns to the earth as rain or snow. Some of the water forms streams and lakes and some soaks into the ground, but the cycle repeats as water evaporates again.

In a similar way, carbon atoms move through a cycle. Carbon is a part of all living things. It’s part of the ocean, air, rocks and animals. In the air, carbon is attached to oxygen, forming the gas molecule known as carbon dioxide (CO2).

Plants use the carbon dioxide as food to grow in a process known as photosynthesis. During photosynthesis, carbon becomes part of the plant while oxygen is released to the atmosphere. When the plants die and decompose with the aid of worms, insects and bacteria, some of the carbon becomes part of the soil. Animals and animal waste are also part of the carbon cycle.

One way carbon is released back into the atmosphere is as CO2 when we burn things. Animal respiration and volcanic eruptions are other examples of carbon being released back into the atmosphere.

The amount of CO2 in the atmosphere has an impact on the temperature of the atmosphere. This is why climate scientists monitor CO2 levels as an indicator of climate change.

Carbon, not unlike water, is constantly on the move in the environment. In the case of carbon, the cycle can be as short as a few days or up to millions of years. Carbon is just one of the nutrients cycled through soil.

Photosynthesis

A carbon cycle game is available at https://www.windows2universe.org/earth/climate/carbon_cycle.html

Carbon is used and stored by plants, some of which decomposes and becomes part of the soil.

Backyard Conservation

Rain GardensA rain garden is a garden that was designed specifically to take advantage of rainfall and stormwater runoff with minimum additional water. The plants are often a low-water-use variety and mulch is used to cover the soil to reduce evaporation and erosion.

In the photographs you can see how the pavement is bordered by the garden. When it rains, the water runs off the hard surface and the garden absorbs some of the water. Stormwater is commonly high in nitrogen and phosphorus, which can be harmful to aquatic life. Rain gardens can filter some of the pollutants before the water reaches nearby streams or lakes. Rain gardens also improve soil health.

For those with limited space, container gardens are another option to add beauty to the urban landscape.

Urban VegetablesYou don’t have to have a farm to grow vegetables. Even if you don’t have a backyard, many cities in Colorado offer space in community gardens. Even rooftops and balconies can provide enough space to grow vegetables or flowers with soil-filled containers.

Rain gardens can be built almost anywhere, including your backyard or school. To find out more about rain gardens and other backyard conservation measures, check out the resources available at www.nrcs.usda.gov.

Carbon in the Atmosphere Carbon Dioxide (CO2) is a greenhouse gas. As levels of CO2 increase in the atmosphere, temperatures rise. One way to reduce the amount of CO2 in the atmosphere is to capture and store more carbon in the soil. This process is called carbon sequestration.

Since healthy soils have a greater capacity to sequester carbon, one way to reduce the amount of CO2 in the atmosphere is to improve soil health.

Soil health is a regular concern for farmers, ranchers, foresters and other land managers, but it’s also a concern in our urban landscape. If you have a yard, a garden, a community garden or even potted plants, you can be part of the solution.

What Soil Does We depend on healthy soils for clean air and water, healthy crops and forests, productive grazing lands, wildlife habitat, beautiful landscapes and support for structures. Soil does this through five essential functions:

» Regulating water—Soil helps control where rain, snow melt, and irrigation water goes. Water and dissolved particles flow over the land or into and through the soil.

» Sustaining plant and animal life—The diversity and productivity of living things depends on soil.

» Filtering and buffering potential pollutants—The minerals and microbes in soil are responsible

for filtering, buffering, degrading, immobilizing, and detoxifying organic and inorganic materials, including industrial and municipal by-products and atmospheric deposits.

» Cycling nutrients—Carbon, nitrogen, phosphorus, and many other nutrients are stored, transformed, and cycled in the soil.

» Physical stability and support—Soil structure provides a medium for plant roots. Soils also provide support for human structures and protection for archaeological treasures.

Text provided by the Natural Resources Conservation Service Healthy Soils program.

StewardshipCareful and responsible management of something entrusted to one’s care

In discussions of agriculture, food, energy and other resources, the term ‘sustainable’ is often discussed. Sustainably-grown, -raised or -produced describes practices that can be continued without causing harm to the environment or consuming non-renewable resources.

Related to the idea of sustainable is a philosophy of stewardship. Farmers and ranchers are commonly called stewards of the land because their livelihoods depend on the health of the soil and animals they care for.

All of us can participate in this idea of stewardship by

being concerned about our environment, the food we eat and by understanding the connections between our lives, soil, water and air.

The soil that grows our food is a living, non-renewable resource. Its preservation is essential for food security and our sustainable future.

The United Nations, the USDA and other organizations have coined 2015 the Year of Soil to raise awareness of soil issues. To find out more, visit www.fao.org/soils-2015/en/ or www.soils.org/iys

Participate in the free international I

“heart” Soil photo campaign!

www.soils.org/iys/stickers