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2015 Year of the Soil!

January 09, 2015

It's official, this year is the year to dig your hands into the dirt! The Food and Agriculture Organization (FAO) of the United Nations has officially declared 2015 the "International Year of Soils". The humble earth beneath our feet is receiving this recognition for a variety of reasons. Soil is the foundation of all plant life on Earth (literally!) from the foods we eat, to the flowers we admire, or the forests that become timber to build tools or homes. Soil plays a critical role in non-living systems as well. It filters and stores ground water, it interacts with the atmosphere and it can play a role in the warming (or cooling) of microclimates.

While all soils serve a similar purpose within their ecosystems, soil is incredibly diverse. Soil comes in a variety of colors, textures, and chemical compositions. Different soils also have their own individual arrays of bacteria. Here within the Roaring Fork Valley, some of this diversity is evident even from a distance. Traveling from Glenwood Springs to Aspen, the soil undergoes a visible change from the bright red, iron-rich soil near Glenwood to the more muted brown tones of the soil up near Aspen.

These soils differ on a less-visible level as well. Among the four study sites that currently comprise the Roaring Fork Observation Network, there are clear differences in soil texture and composition. At Smuggler Mountain, the soil is a slightly acidic, loose loam (a mix of sand, silt, and clay) with less than 1% organic matter. It's low in nitrogen, but high in phosphorus. At Sky Mountain, by contrast, the soil is also a loam, but it is less acidic and more densely packed. The organic matter is much higher--around 11%, and it has more nitrogen available than phosphorus. The Brush Creek site, a meadow, is very different from the two forested sites. It's classified as clay and is nearer to neutral pH than the other two sites. Its organic matter content is around 7% and its nitrogen and phosphorus availability are close to one another. Glassier Ranch which is something of a wetland in the summer, is a sandy loam, and near the surface, it is near neutral for pH and has a high phosphorus availability and 33% organic matter.

The differences in the soils is both driven by and drives the type of plants that live in these areas. For example, at Smuggler Mountain, the low nitrogen availability may limit what types of plants are able to establish and succeed in the area. Meanwhile, the fact that the dominant vegetation in the area are conifers likely contributes to the acidic nature of the soil. (Needles from conifers tend to lead to acidic soils when the decompose.)

Soil is an important determinant in the type of ecological communities you find, no matter where you go on Earth--and the relationship is reciprocal. So what does the soil like where you live? 2015 is the year to find out!

Digging in at Brush Creek. Image Credit: AGCI, 2014