NEWS

Wednesday, March 26, 2014

Rebuilding the Earth’s soils

As rising food demands place ever more pressure on the world’s soils, can a smartphone app for soil health unlock a global win-win-win for climate, societies and the environment?

We predict that it’s only a matter of time before you start seeing soil scientists (yes, soil scientists) gracing the front covers of our most prestigious fashion, tech and lifestyle magazines. Why? Well, the world’s soils contain about 2.3 trillion tonnes of organic carbon. That’s more than the carbon in the atmosphere, all of the world’s forests and all remaining fossil fuel reserves put together. This carbon stored in ecosystems and soils is the result of an ancient equilibrium. Every year tens of billions of tonnes of carbon are taken up and added to soils by plants – and similar amounts are released to the atmosphere through decay and other natural processes.

Just as with the extraction and burning of fossil fuels disrupting the planet’s carbon cycle and the atmosphere’s energy balance, human activity has disrupted the exchange between the air and the soils on a comparable scale. Losses have been accelerated by clearance, overgrazing and ever more intensive, “production line” agriculture that prioritises short-term yields over long-term soil health. It is estimated that over the whole Anthropocene, since the dawn of settled agriculture about 10,000 years ago, between 200 and 500 billion tonnes of this carbon has been released from soils into the atmosphere, compared to 365 billion tonnes from burning fossil fuels.

Soil health is at the root (no pun intended) of all agriculture, from the most traditional practices to the most advanced, industrialised systems (credit:The Knowles Gallery /43rdSB | Foter | CC BY-SA)

How can we start to reverse ten thousand years of losses and tip the global balance back towards carbon sequestration and healthy, long-lasting soils? Last month we paid a visit to the James Hutton Institute in Aberdeen, a globally renowned centre of agricultural and soil science where they are tackling this question. It turns out that there are plenty of quite straightforward and low-cost ways that farmers across the world can use their soils more sustainably: simple measures like changing the ploughing regime, trying new crop rotations, adding mulches or manures or controlling the movements of grazing animals can start to turn fields and grasslands back into carbon sinks.

But if these methods are both so simple and so beneficial, why aren’t farmers already doing them? The problem is that there is a big gap between the science and applying it in reality. First, no two soils are quite the same, and a given practice can yield different results in different contexts. Crucially, whether or not a particular practice will bring any benefit at all depends on the soil type, texture and composition, the local rainfall patterns and temperature, the slope of the land, the crop you’re trying to grow and how the soil has been managed in the past. This complexity is compounded by the fact that farmers themselves are often understandably reluctant to take the risk of changing methods that they may have practised for generations, particularly since it is often their entire livelihood that is at stake.

“you need to find what works for each individual place if you’re really going to make things better”

Enter Dr. Matt Aitkenhead of the James Hutton Institute’s latest project: a smartphone app that aims one day to provide farmers worldwide with tailored advice on how to improve their soils. They have recognised that the biggest barriers to unlocking the potential of soil carbon are not technical; they are informational and behavioural. All the farmer will need to do is dig a small pit and take a photo of the soil profile. The app will then feed this information and the geo-location to the James Hutton Institute, where it is checked against maps to identify the local soil type, climate, geology and topography. Next, a set of ingenious neural network models, trawling vast soil science datasets, puts all this information together.

Drawing on all the global soil science community’s accumulated knowledge and local expert advice, it will use all this to generate a series of simple and bespoke steps that the farmer can take to improve their soils. Finally, by the way, it’s likely that a lot of these measures can enhance soil carbon content, which can then be measured by the app as well.

The app calculates the soil organic matter (OM) and organic carbon (C) using only the photo and the geo-location to better than 0.5% accuracy. Credit: James Hutton Institute.

The project has planet-scale ambition, but there’s a long way to go. The latest version can predict soil carbon levels anywhere in Scotland from a photo, but they need a lot more data to make it work across the world. And the most important part of the tool – the part that puts it all together to generate the suggestions for farmers optimised to their geography – is still only an idea right now. There are a lot of unanswered questions: Will the models be able to work out the right advice for such a huge diversity of contexts? How will the project reconcile the latest science with a respect for traditional agricultural approaches that have evolved over generations? And how will it convince farmers across the world to take a chance with their livelihoods – and to stick at the new methods long enough to feel the benefits?

The National Soil Archive at the James Hutton Institute, thousands and thousands of unique location-tagged soil samples providing baseline data for all sorts of soil science.

It will take a lot of hard work across the board to answer these questions, from the most theoretical academic soil science right down to trying out and testing these ideas on the ground in real farms across the world. But the strength of the James Hutton Institute’s approach is that they accept straight away how complex this problem is, and that there is no single, simple solution. The philosophy of their approach is that instead of looking to roll out one particular land management practice, or even a standard ‘five point plan of sorts’ you need to find what works for each individual place if you’re really going to make things better.  And that is as true of the farms and local communities as it is of the soils. If this ambitious programme can combine such a respect for context and complexity with the latest innovations in sensing and big data, the work may stand a good chance of making some real progress on this critical global challenge – helping to truly and equitably unlock the global benefits to societies, economies and environments that taking care of our soils can yield.

By Guy Lomax