Written by Tandra Fraser, 2015-2016 Sustainability Leadership Fellow and Postdoc at the School of Agriculture, University of Reading, London.
What do the Great Plains of North America, the tropical hillsides of Honduras and the valleys of Antarctica all have in common? The answer is soil, of course!
Soil is the foundation of terrestrial life on earth wherever you may travel. Located at the interface between the atmosphere, biosphere, lithosphere and hydrosphere, it is the naturally occurring surface layer formed by complex processes and interactions. Being raised on a farm in the Great Plains of Canada, I was connected to soil from a very young age as I went from making mud pies to growing food. Nowadays, as a soil scientist, I get to explore soil, its many uses, and its inhabitants.
Soil is the basis for much more than just agriculture. For example, in rural Honduras, the same soil that is used for growing staple crops such like maize, beans and coffee, is also used for building adobe houses, creating functional pottery, and even building stoves to cook the food they grow.
These same soils provide a home to countless soil organisms, including everything from large burrowing creatures such as badgers to microscopic worms, bacteria and fungi. Although we cannot see many of these species with the naked eye, they play an important role in all of our lives.
n many regions of the world, mineral fertilizers are not an option for crop growth and producers must depend on soil organisms for nutrient cycling to provide nutrients for plant growth. Organisms in the soil have evolved mechanisms to obtain nutrients. For example, many bacteria excrete enzymes into the environment when they do not have enough phosphorus to function and/or grow. These phosphatase enzymes can break down an unusable form of phosphorus that occurs naturally in the soil, into orthophosphate that can provide nutrition to the organism and will eventually be released into the environment and can be taken up by plants.
The critters that live in the soil, and their activities, involve many complex interactions between chemical, physical and biological components. These organisms aren’t just interesting to look at, they also provide essential ecosystem services upon which all plants, animals and humans depend. Although soils are extremely heterogeneous, organisms are contributing to decomposition of organic matter and nutrient cycling, regardless of the ecosystem.
Even in Antarctica, one of the windiest, driest and coldest places on earth, the soil is alive. Although the soil food web is less complex than it may be in a tropical forest, soil animals and the microbial communities play an essential role in the functioning of this pristine ecosystem. It is common to find nematodes, tardigrades and rotifers living in these soils. But even this region is not immune to global change as demonstrated by research as part of the McMurdo Dry Valley Long Term Ecological Research (LTER) Network. This site has been essential in demonstrating how the ecology in the soils of the region has been changing over the past 25 years. It also emphasizes the interconnectedness of the glaciers, lakes, streams, soils and air and the far reaching effects of human activities.
At all corners of the globe, soil and its life are constantly being threatened by human activities and global change. Land is being degraded at astonishing rates and this ultimately has an effect on food production, water quality, and pest and pathogen control, to name a few. The economic cost of land degradation is US$40 billion each year, as estimated by the United Nations Food and Agriculture Organization. As cities continue to expand, soils are paved over and organisms are unable to function, and humans, literally, become disconnected from the land, separated by a layer of concrete.
“The soil is the great connector of our lives, the source and destination of all.” - Wendell Berry, The Unsettling of America, 1977
Despite the fundamental importance of soil for all plant, animal and human life, it is often taken for granted. Scientists, policy makers and land managers must all work together to identify and implement solutions for conserving soil and all that live there. The Global Soil Biodiversity Initiative has been working to raise the profile of soil biodiversity and all its wonder around the world.