Did you know that there are nearly 70,000 different types of soil in the United States?1 With the abundance of natural beauty that we see above the ground, it is easy to overlook all the roles that soil plays in our ecosystem. Soil does much more than simply providing the canvas for green spaces; it serves as the groundwork for rural and urban farms, marshes and bayous, and forests. Soil also serves as the foundation for our homes, a natural filtering system for clean drinking water, a mediator for clean air, and a medium for life.
This year, 2015, is the International Year of Soils, and World Soil Day was just celebrated on December 5, 2015. Initiated by the International Union of Soil Sciences in 2002, this is a day for us to highlight and celebrate the integral role that soil plays in the health of our ecosystem. With a few small changes to our agricultural practices and a renewed focus on sustainable land use practices, perhaps we can preserve the many benefits of healthy soil. Now let’s dig deep and learn a little about the ground beneath our feet.
What is Soil?
Soil is a mixture of minerals, clays, organic materials, and soil dwelling organisms. It takes an astonishing minimum of 500 years to form 1 inch of topsoil from all of these ingredients! Once the soil is there, it will gradually erode away again through natural environmental processes such as wind, flowing water, and animal activity. However, soil erosion can be exacerbated by poor agricultural and industrial practices (see for example the U.S. Dust Bowl of the 1930s). Within the last 150 years, nearly half of the topsoil on the planet has been lost.2 The time that it takes to generate new topsoil makes soil essentially a non-renewable resource. Therefore, we need to make sure that we take care of the soil that we do have by creating sustainable land use plans and observing good soil health practices.
What Does Soil Contribute to Our Society?
This is not an exhaustive list of the many contributions of soil, but I have highlighted some ways that soil makes a difference in our lives.
Food Source: Soil is the “birthplace” of most of our food sources. Soil retains many of the nutrients and provides much of the water that plants use to grow. Without it, we would not have fruits, vegetables, herbs or plants. In addition, many of our livestock animals that eat grasses and plants would not be able to sustain themselves.
Carbon Storage: Carbon dioxide, or CO2, is a greenhouse gas that has garnered much attention as it is thought to have a large impact on global climate and climate change.3 Carbon stored in soil accounts for a significant amount of carbon stored in terrestrial ecosystems.4 Loss of soil can lead to the emission of the gas buried there. In addition, removal and degradation of soil reduces the capacity of carbon that can be stored in the future. There is hope that we can mitigate the adverse effects of carbon release from these systems. Efforts to increase the amount of stored carbon include reforestation, sustainable land use practices, and the restoration of wetlands.2,5
Water Filter: Soil has the ability to store water and filter it through many processes, including adsorption of heavy metals. Some nanoparticles that naturally occur in soil (as Sam Lohse pointed out in this post) can slow or stop some harmful water contaminants from making their way into the groundwater and drinking water. For example, iron oxides (like magnetite, hematite, and goethite) naturally occur on the nano scale in addition to their bulk forms.6
Storm Buffer: Soil serves as the basis for many important ecosystems including wetlands. These systems are the bridge between land and water and serve many functions for our environment and even our economy. Wetlands can serve as storm buffers protecting us from the brunt of any cataclysmic forces from hurricanes and tsunamis. Wetlands are able to store a tremendous amount of water, thereby reducing the extent of flooding.7
Threats to Soil Health
Overuse of soil, poor soil health management, and the use of chemical pesticides are just some of the suspected causes of excess soil erosion. Soil erosion can have additional side effects, such as the reduction in the number of bacteria in the ecosystem. As we know from Lyle’s post on Shewanella oneidensis, this could spell disaster for our fragile environment. Another consequence is that as the soil erodes, many nutrients retained in the soil can be transported into the ground and surface waters. This can disrupt the natural chemistry of surrounding lakes and ponds.
What Can we do?
It is clear to see that soil is a very important natural resource and one that we cannot live without. Here are a few things that you can do to improve soil health:
- Develop a management plan for your home gardens and farms. Consider using cover plants or rotating crops to reduce the stress on soil, and minimize the use of pesticides and fertilizers.
- Start your own compost. Food scraps and biodegradable items can make excellent nutrient sources for soil. Why send it all to the landfill when it has a purpose right in your backyard?
- Grow what makes sense. Different types of soil can support different types of agriculture. Do not try to force a square peg in a round hole by growing your plants in the wrong environment. Take the time to learn about the things that will grow best.
- Last but not least: Do your research! Learn more about the best practices for soil management.
(If you have more suggestions for saving our soil or best management practices please share them in the comments!)
In celebration of the International Year of Soils, make sure that you take the time to think about the critical role that soil plays in nearly every facet of our lives from food and energy to our economy and health. Happy World Soil Day!
EDUCATIONAL RESOURCES
- University of Illinois Extension: “The Great Plant Escape” activity on soil types
- Utah State University Extension: “Dirt: Secrets in the Soil” series of modules & resources
- Starrs, S. Dig It! The Secrets of Soil. Smithsonian National Museum of Natural History: http://forces.si.edu/soils/index.html
- World Wildlife Fund. Soil Erosion and Degradation: http://worldwildlife.org/threats/soil-erosion-and-degradation
- U.S. Environmental Protection Agency. Causes of Climate Change: http://www3.epa.gov/climatechange/science/causes.html
- Nichols, J. E.; Peteet, D. M.; Moy, C. M.; Castaneda, I. S.; McGeachy, A.; Perez, M. Impacts of Climate and Vegetation Change on Carbon Accumulation in a South-Central Alaskan Peatland Assessed with Novel Organic Geochemical Techniques. Holocene 2014, 24 (9), 1146-1155. doi: 10.1177/0959683614540729
- U.S. Environmental Protection Agency. Principles of Wetland Restoration: http://www.epa.gov/wetlands/principles-wetland-restoration
- Jentzsch, T. L.; Chun, C. L.; Gabor, R. S.; Penn, R. L. Influence of Aluminum Substitution on the Reactivity of Magnetite Nanoparticles. Journal of Physical Chemistry C 2007, 111 (28), 10247-10253. doi: 10.1021/jp072295+
- U.S. Environmental Protection Agency. Why Are Wetlands Important? http://www.epa.gov/wetlands/why-are-wetlands-important
Sustainable Nano 