Discovering Hidden Treasures in 100 Years of Soil at the National Archive

By Lish Fejer

Topic: Soil

Soil samples from over 30,000 sites across Australia are stored at the CSIRO's collection, with some being a century old.

Rifling through boxes of soil at the Australian National Soil Archive reveals more than meets the eye.

The collection, stored in shipping containers, holds a century of samples.

Archive manager Georgia Reed sorts through, archives, and stores the 100,000 samples from over 30,000 sites across Australia.

This collection represents a slice through time of the ground beneath our feet.

Georgia Reed is currently sorting through around 20,000 unarchived soil samples.

The most exciting project Georgia Reed found is the Simpson Desert Expedition from 1939.

'Soil is not dirt'

Leader of the CSIRO's Soil and Landscapes Group, Ben Macdonald, said soil and dirt are not the same thing.

Soil is a living thing, while dirt is a dead thing.

Dirt is just powder on the ground.

Dr Ben Macdonald says soil is essential to how the Earth functions.

Soil is a biological medium with minerals and life forms.

Ecosystems start from soil, even in desert ecosystems like the Simpson Desert.

It's certainly not a dead heart.

The Simpson Desert is a very productive and vibrant landscape despite low rainfall.

People called it the dead heart due to low agricultural productivity, but the ecosystems are vibrant.

Soil is a living biological medium that regulates the atmosphere and interacts with water.

Soils of the century

The Australian National Soil Archive is a library of what the land was like at different points in time.

When we disturb the soil, the carbon content goes down.

New things have turned up over the last 100 years, such as plastics and radiation fallout.

The Australian National Soil Archive contains 100,000 soil samples from over 30,000 sites across Australia.

New technology is allowing soils to be analysed with near-infrared spectroscopy.

This technology can predict soil carbon content in 20 seconds.

Detective work matches samples

The CSIRO combined its soil collections at the Black Mountain campus in 2003.

There are around 20,000 unarchived samples from the 1920s to the 1960s.

The data is all in physical cards called pink cards.

The CSIRO's soil sample collections were consolidated at its Black Mountain campus in 2003.

The samples are in jars, calico bags, and plastic containers with a number on the outside.

It's like having a bag of jigsaw pieces without the box.

Citizen scientists are transcribing 19,000 digitised pink cards to match them to a sample.

I look for publications relating to those samples.

The researcher might have published papers on them, giving metadata like how they took the sample.

Sometimes she strikes gold — or red.

Georgia Reed identified the soil samples taken from the Simpson Desert in 1939 by their pink cards.

One sample was collected in 1939 on Dr Cecil Thomas Madigan's camel expedition across the Simpson Desert.

Soil surveyor Robert Langdon Crocker took samples, filling calico bags and numbering each sample along the route.

Ms Reed found them by cross-referencing Mr Crocker's publication with handwritten field pink cards.

I could see in RL Crocker's publication that he'd recorded the sample numbers.

From there, I could find a map that's published online and geolocate the sites.

Dr Cecil Thomas Madigan preparing for his camel expedition across the Simpson Desert in 1939.

Ms Reed said the discovery was a bit surreal.

That was really exciting because we didn't know we actually had those samples here in Canberra.

What comes next?

Dr Macdonald said the collection for the last 100 years has been rather piecemeal.

Looking to the next century, a new snapshot of soil is currently being collected.

Dr Ben McDonald says for the last century the collection has been a bit piecemeal, but that's set to change.

Thousands of new soil samples from sites across Australia will be added to the archive.

The program involves collecting 25,000 new samples to establish the first ever continent-wide baseline of soil health.

The samples will be ingested into the archive, and in three to five years, a second round of collection will begin.

The goal is to track whether soil carbon is rising or falling and guide policy and action.

With global fertiliser supplies under pressure, there's a renewed spotlight on the ability of our soils to sustain us.

Being able to have fertile soils to grow crops is crucial, especially with constrained nitrogen fertiliser.

It's where the food system starts.

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