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Guest Opinions

International Year of Soils Celebrated

Written by Sharl Meeks

By Shari Meeks, JIO/PAPO Ag Program Coordinator, Wyoming Department of Agriculture

No one in agriculture needs reminding of the importance of high-quality topsoil. But this is not generally true for the entire population, who considers soil as no more than the dirt we sweep up in our homes and wash off our vehicles. A healthy soil is the foundation for food, fuel, fiber and medical products and is the most vital – and most overlooked – part of our ecosystem.

The 68th United Nations (UN) General Assembly declared 2015 the International Year of Soils (IYS) to increase awareness and understanding of the many important roles of soil. Together, with international partners, the Natural Resources Conservation Service (NRCS) and Soil Science Society of America (SSSA) will be showcasing the importance of soil with monthly themes created by the SSSA. These themes vary by topic from soil biology to water filtering capabilities to agricultural significance and urban life support. Activities and more information about the monthly themes can be found at soils.org/iys.

In light of the 2015 International Year of Soils, let’s take a look at our very own landscape in Wyoming.

Wyoming’s state soil

Soils throughout the world all possess characteristics making them unique – from soil color and texture to soil depth. According to the NRCS, a state soil is any soil with specific significance to a state. Twenty state soils have been legislatively established and have the same level of distinction as state birds and flowers. 

The Wyoming state soil is Forkwood. This soil is located predominantly in the north and east portions of the state as shown in the bottom figure on page 12. Wyoming’s semi-arid climate allows the Forkwood soils to support native plants such as bluebunch wheatgrass, Wyoming big sagebrush, needle and thread grass and various native forbs. Wyoming’s native rangelands are a very productive ecosystem and, with proper management techniques, will continue to be a sustainable resource for our state.

The Forkwood soil has unique characteristics. The soil profile doesn’t look too intriguing, but it holds a lot of information regarding why it can only sustain the plant community it does. 

Soil horizons

The “A” and “B” Horizons are the most important horizons for plant growth. The surface layer called the “A” Horizon is approximately three to five inches thick. Organic matter comes from decaying plant litter and is a source of soil fertility. Organic matter also influences soil structure at the surface. A nice granular structure is best to achieve good water infiltration.

The subsoil or “B” Horizon is approximately eight to 12 inches thick. Over thousands of years, clay particles and some organic matter leach through the profile during periods of rainfall or snowmelt and settle in this portion of the soil profile. Clays can bind water and nutrients, making the plants work harder for those items vital for growth.

Due to the nature of plant structure, most plant roots do not extend down to the third and fourth horizons. Lime has accumulated in these parts and can be limiting to plant growth. Should the topsoil, in this case the upper 12 inches of the soil profile, be stripped away, these bottom horizons would unlikely be able to support the same plant community as we see on the landscape now. 

Unique characteristics

Forkwood’s soil characteristics, partnered with climate, pose limitations on what the soil can be used for. These soils are typically used for rangeland and wildlife habitat and are considered unsuitable for row crops. 

The Forkwood soil is dominant on our landscape, but there are many other unique soil types in Wyoming. These include soils with high salt content, forest soils and soils with bedrock near the surface. Each soil comes with its own limitations and characteristics.

Importance to producers

Whether you are grazing cattle or farming, knowledge of soil can help make decisions important to your operation. Clayey soils support different vegetation than sandy soils. This can affect everything from carrying capacity of cattle for beef producers to choice of crop for farmers. 

The NRCS has tools available to the public, including the Web Soil Survey, available at  websoilsurvey.sc.egov.usda.gov/App/HomePage.htm, where you can look up a parcel of land and find soil information particular to that property. 

If you are not able to utilize their website, you can always go to your local NRCS office and talk with the Range Conservationist. The University of Wyoming Extension offices also have folks to steer you in the right direction. 

Another resource is the Smithsonian National Museum of Natural History. They have a great website at forces.si.edu/SOILS/interactive/statesoils/index.html displaying each state’s soil. What a great way to compare and contrast soils from around the nation!

Soils are dynamic. They support agriculture, filter and capture water, support buildings and infrastructure, support health and recreation, and ultimately sustain life. In honor of the International Year of Soils, don’t treat your soil like dirt!