Over the past 40 years, a third of the world’s farmable land has been wiped out by erosion and pollution, researchers say. This has the potential to become disastrous, as the demand for food soars worldwide.

According to experts from the University of Sheffield’s Grantham Centre for Sustainable Futures, almost .

“Soil is lost rapidly but replaced over millennia and this represents one of the greatest global threats for agriculture. This is catastrophic when you think that it takes about 500 years to form 2.5 centimeters of topsoil under normal agricultural conditions,” said University of Sheffield professor of plant and soil biology Duncan Cameron. “A sustainable model for intensive agriculture could combine the lessons of history with the benefits of modernbiotechnology.”

The photo above shows an aerial view of a farmer cropping root vegetables such as carrots and parsnips on a field near Pattensen in the Hanover region, central Germany on Nov. 26, 2015.

(JULIAN STRATENSCHULTE/AFP/Getty Images)

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The decline in soil has come at a time when the global demand for food is growing at a rapid rate. It’s estimated that to feed a projected population of 9 billion, reports The Guardian.

The erosion of soil is largely due to constant disturbance from planting and harvesting crops. If soil is continually turned over it is exposed to oxygen which makes it , causing it to fail to effectively bind. This diminishes the soil’s ability to hold water, to buffer flooding and provide a base for plants. These compromised soils are also more likely to be washed away.

Intensive agriculture methods in place requires the heavy use of fertilizers, which need high energy inputs to supply inorganic nitrogen. This process takes up five percent of the natural gas production and two percent of the world’s annual energy supply, experts said.

“In order 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 resolve the potential benefits of this redesign for sustainability,” said Grantham Centre associate director Peter Horton. “In doing so, we could reduce our dependence on energy-intensive and non-renewable inorganic fertilizer, reduce fertilizer pollution of watercourses, and create a soil fit for future generations.”

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According to Cameron and his team, a is based on three principles:

Managing soil by directly applying manure, rotating annual and cover crops, and practicing no-till agriculture by not cultivating the land. These ‘conservation agriculture’ practices will help restore soil organic matter, structure, water-holding capacity and nutrients, as well as benefit crops while averting soil loss.Using biotechnology to enable plants to initiate and sustain close interactions with soil microbes. This allows them to use microbial biology to tap into nutrient reserves and better defend themselves against pests and diseases.Manufacturing inorganic fertilizers from human sewage in biorefineries.

“Of course, no one model equally fits all problems; different agricultural scenarios such as varying geography, climate or crop might benefit from our approach more than others and any redesign of the agricultural system needs to be sufficiently flexible to accommodate this,” said Horton.

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