What Lies in the Soil?

By October 29th, 2013 at 2:00 pm | Comment

Drag your bones toward even more Halloween-themed citizen science!


We know from basic ecology that organisms are adapted to their environment, and where certain organisms live should fall along a gradient of critical environmental factors such as moisture, temperature, nutrient availability, or substrate. How these factors impact diversity and distribution are questions that we could solve for macroorganisms like trees, but the hidden world of microbes still has yet to yield the answers to these mysteries.

Dr. Andy Whiteley and Dr. Christine Whiteley are investigating these questions with MicroBlitz, a citizen science project centered at the University of Western Australia. They’re interested in digging up soil and finding out what lives inside. To do this, they’ve been enlisting the help of volunteers around Western Australia to sample soil. Volunteers go out, bite into the earth with a shovel, and send their specific blend of microbes to the University of Western Australia for Dr. Whiteley to analyze.

To understand this, it’s useful to think of the Gaia hypothesis. This is the idea that the entire Earth, as a biosphere, acts as a living organism. We can imagine soil in a similar light. It’s not actually living but is a teeming metropolis of trillions of microscopic citizens. In a fistful of soil, you might find 10,000 different species of microbe. Dr. Whiteley describes it as “a rainforest under your foot” with each footfall. Soil microbes are the powerhouses of many biogeochemical cycles on the planet, turning over oxygen, carbon, nitrogen, phosphorous, and sulfur, and are critical to plant growth and productivity. They work unceasingly and are, in a way, the hidden machinery of the planet.

You can imagine microbes as being somewhat specialized. There are bacteria that eat sulfur and others that eat nitrogen, such as Rhizobium, a genus of nitrogen-fixing bacteria found in soil. While you might find these bacteria in many places, presumably you would expect to find more in areas that naturally have more nitrogen or perhaps in areas that have added nitrogen due to industrial processes. And depending on environmental conditions, each place cultivates a specific mix of microbes. There would be certain bacteria that one might find associating with farms or a river. This is what MicroBlitz is trying to understand, and more precisely, trying to map where these bacteria are and what kinds of conditions generate one population of microbes over another.

The project grew out of a similar survey that Dr. Whiteley had done in England in 2007, where they completed a map of soil microbes with the help of trained scientists. It was possible to do it that way, Dr. Whiteley affirms, since there’s less land than in Australia and more scientists per square kilometer. Now two years later, beginning in the March of this year, MicroBlitz is working with the help of citizen scientists to do a map of a much larger scale. Without a large number of MicroBlitz volunteers, the project would be impossible since the territory to cover in Western Australia is vast. How many citizen scientists exactly? Deborah Bowie, the project manager for MicroBlitz, says hundreds have registered, “We’ve sent out over 750 sampling kits so far. People from all over the state are involved, sometimes individually, and sometimes through a group.”

In order to find out what’s inside the soil samples they get, Dr. Whiteley and his lab freeze the soil and extract and sequence the DNA of the microbes. They can use this information to find out what species are living inside the soil and how many of each there are. The data are then uploaded to their website and are accessible for all to appreciate. Whiteley hopes the maps will be available soon. “I’d like to use satellites linked to our maps to understand country-scale levels of things such as microbial mediated greenhouse gas emissions – having the maps let us potentially calibrate this approach,” Whiteley says. Once maps are available, Whiteley plans to be able to repeat the process and begin understanding how environmental change might be affecting the soil and what the soil might be affecting, such as global warming.

The goal is currently to get as many samples from as diverse places as the MicroBlitz team can get. So Whiteley and Bowie often go to under sampled areas to reach out to people, teach them about the project, and encourage them to get involved. Both Whiteley and Bowie agree; it’s the best part of the project. “We ran a DNA workshop for seniors, and they loved it. It was something they had never experienced before … extracting DNA from strawberries, but the smiles on their faces and the feedback will stay with the whole team forever,” Dr. Whiteley says. The project helps teach science to the community and connect them to their environment by showing them what lives beneath their feet.

The MicroBlitz website is currently under construction and will be available in the coming months. You can get involved there or through the SciStarter portal.

Photograph: Deborah Bowie

Angus Chen is the managing editor for the SciStarter Blog network which includes the Discover magazineCitizen Science Salon” blog and the Public Library of Science’s Cit Sci blog. He’s also a freelance reporter and producer at WNYC Public Radio on “The Takeaway” with Public Radio International and the NY Times. You can also read his work with Science magazine. He was once a scientist studying geology and ecology, but now spends his days typing and scribbling and sketching furiously. When he gets the time, he makes cool videos.


Leave a Reply