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Author: A. Horvath
Source: The Age
Date: 9th April 2015

Just one gram of soil from your garden contains billions of microbes and those microbes are essential for life on Earth. It’s also a humbling thought for humans that the number of bacteria that live in and on our bodies is 10 times greater than the number of cells that make up our bodies.

Certain bacteria are critical to our metabolism, digestion and immune systems. The overall ecology of microorganism numbers, types and interactions dictates our health status. It is the same for soil, the numbers, types and interactions of microbes allow soils to be ‘alive’ with activity, which is critical to the capacity of the soils to cycle nutrient elements like carbon, nitrogen and phosphrous, supporting plant life and its associated ecology, and that includes us.

The year 2015 celebrates International Year of Soils and raises awareness and promotes the sustainability of our limited soil resources. Dr Hang Wei Hu, at the Faculty of Veterinary and Agricultural Sciences comments on how he became interested in soil microbiology.

“When you study biology and ecology you begin to realise it’s the recycling activities of soil that underpins the growth of plants and foods, the quality of the water and air, and therefore the ecology of every landmass,” Dr Hu says.

“When I was studying science in China, subjects like biology and genetics were the most popular but I remember reading in the journal Nature that soil science is one of the last frontiers of discovery and there were still many unanswered questions important to the future of agriculture, food security and natural ecosystems.

“Pollution, land use practices, and extreme weather events do change our soils, so understanding changes in soil microbiology and biochemistry is essential to help future farming, land care and the environment. It all starts with the soil and viable soil is a limited resource,” Dr Hu says.

Dr Hang Wei Hu currently works with Professor Jim He, who joined the University of Melbourne as part of the Research at Melbourne Accelerator Program (RAMPA) as Professor of Molecular Soil Ecology.

Professor He’s research team and many collaborators work on soil microbes and ecosystems examining the distribution and diversity of microbial communities. They also focus on microbe-mediated cycling of carbon and nitrogen, the essential recycling of elements that ubiquitously occur in soils. It’s these processes that propel the biochemistry essential for life on Earth.

Their latest paper examines what happens to microbial activity in soil samples under the conditions of climate change such as elevated CO2 and extreme weather events. They collected soil samples from different sites across Australia and incubated them under conditions of elevated CO2 and temperature.

“After one year of elevated CO2 the impact on soil microbes was significant as they decreased in number and the interactions between the microbes was also reduced,” Dr Hu says.

“The rate of nutrient uptake was altered which affected the cycling of elements like nitrogen which are critical for plant growth. The health of soils became fragile.

“Samples from already nutrient poor environments like dry lands and grassland ecosystems were even more affected by high CO2 levels.

“The stability of soils is clearly at risk by climate change,” Dr Hu says.

Once a soil has changed it can take anywhere between 10 to 100 years for it to recover and return to its original state. The research of soils and the microbes takes on a whole new level of scientific imperative.

There is no doubt soil microbes really do rule the earth, and us.

Read more at The Age.