Combining lessons from agricultural history with insights of modern biotechnology is key to reversing the degradation of the world’s soil.
This was the powerful message Sheffield’s researchers gave to leading policy makers on the eve of the 21st Conference of Parties on Climate Change (COP21).
Speaking at Chatham House, plant and soil scientist Duncan Cameron, and Colin Osborne, an expert in the evolutionary and environmental physiology of plants, warned that time is rapidly running out for a change in direction.
Failure to act quickly could trigger food shortages around the world. This would have knock on effects in increased mass migration, political and social instability and conflict.
“The current system consumes 5% of the world’s natural gas and 2% of its energy. This is not sustainable,” says Professor Cameron. “And yields from a number of key crops have been flatlining for the last fifteen years. The model doesn’t work.”
Their research shows the degraded status of the world’s soil is largely responsible for this yield plateau. “Soil is lost rapidly but replaced over millennia. This represents one of the greatest global threats for agriculture.”
Cameron and Osborne have discovered that elite modern crops have lost their natural partnerships with microbes. These partnerships are vital, because they work to extract complex nutrients from the soil and build up their defences against natural enemies.
“Soil is becoming a hydroponic system: a physical substrate to support plants, but providing little else. Deep ploughing has caused a decline of soil organic carbon. This has adverse effects for water-holding abilities. It also affects the natural supply of nutrients, and causes a loss of structure that allows rapid soil erosion,” says Professor Osborne.
But the Sheffield team believe that all is not lost. “Our nineteenth century farming forebears had little access to artificial fertilisers. Consequently they had to manage the soil well. The combined application of manures and crop rotation recharged soil carbon and nutrients. Further, it rebuilt the soil’s physical structure.”
While this method is still practised on organic farms, the yields are too low to be able to sustain a growing global population. “But a combination of the lessons of history with the benefits of modern technology could provide a sustainable model of intensive agriculture,” Cameron and Osborne argue. The clever rotation of annual and cover crops, plus the application of manure, will restore the vitality of the soil.
Biotechnology could wean crops off the addictive chemical cocktails they have become dependent upon. And, in a Back to the Future scenario, we could even recycle sewage in industrial scale biorefineries to create a modern example of a sustainable, circular economy.
“A sustainable soil-centric reengineering of the agricultural system then leads to lower requirements for fertiliser inputs and pesticide application, as well as reduced irrigation, thus safeguarding finite natural resources,” the two researchers told the gathering of policy makers and fellow researchers.
Perhaps the biggest hurdle to adopting this approach, however, is not the technical and scientific challenges, but the political, economic and social obstacles. “To facilitate such a wholesale redesign of the agricultural system, we need to assess the potential scientific, economic, cultural and political impediments to this happening. And we need to resolve the potential benefits of this redesign for sustainability.
In doing so, we could create a soil fit for future generations, reducing our dependence on energy-intensive and non-renewable inorganic fertiliser supplies as well reducing pollution in watercourses as a result of fertiliser run-off.”
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