Massive amounts of fertile agricultural land are lost every year. Yet we depend on such topsoil as the basis for feeding the world. So, what needs to be done to assure healthy soils and thus food security?
Worldwide deterioration of soil quality is a disaster in the making, warn experts like Jes Weigelt of the Institute for Advanced Sustainability Studies in Potsdam, Germany.
"The situation in many regions of the world is very serious," said Weigilt, who coordinated Global Soil Week in Berlin. "The world population is growing steadily. But usable land is shrinking," Weigilt stated.
"Every year, 24 billion tonnes [metric tons] of fertile soil is lost: through erosion, development, flooding, mining - or through intensive agriculture."
Not all ground is fertile
Land is not the same as soil, explained Luca Montanarella of the European Commission. He heads the European Soil Bureau Network on Lake Maggiore in Italy.
Arable land is being lost at a rate of 1,000 square kilometers (386 square miles) per day, Montanarella says. He clarified that the biggest losses are from the construction of roads, cities and industrial facilities.
Removing, sealing and compacting soil kills off the billions of microorganisms, bacteria and fungi that make a handful of earth a living microcosm. Once that life has been eliminated, all that remains is dead matter.
"Soils are renewable," said Montanarella. "But we [creation of fertile soil takes] thousands upon thousands of years - not time spans that we can count in human generations."
Soil preservation as development goal
Soil experts in the European Commission hope that the worldwide protection of soils will find a prominent place in the new sustainability development goals (SDGs) to be adopted by the UN general assembly in fall. These SDGs provide the political foundation for sustainable development in developing and industrialized nations.
For Montanarella, soil conservation counts among the most important requirements for sustainable development. And agriculture in particular must become sustainable, he thinks.
"If we want to maintain food production in Europe, we must protect our most fertile soils from destruction," said Montanarella.
And he highlights another problem: "Regions like the European Union do not have enough soil for their own consumption, and are therefore dependent on imports from other countries."
EU countries import 35 million tons of soy beans and soy meal from north and south America every year - to use as feed for pigs, chickens and cows.
Cultivation of primarily genetically modified soy for export uses land in developing countries that could go toward sustainable agriculture.
But even in industrialized countries like Germany, globalized industrial livestock farming presents a pollution problem.
"[Animal waste] is the root of considerable environmental problems in Germany, particularly in regions with intensive livestock farming," explained agrarian economist Knut Ehlers of the German Environment Agency.
Although manure is also a fertilizer, too much is toxic for soil and water. The environmental impacts of factory farming "ultimately fall on the taxpayer," said Ehlers.
Such agriculture is unsustainable, Ehlers stressed. He hopes that aiming more public attention to the issue of soil depletion on the national and EU levels will lead to more sustainable policy-making, and development of organic agriculture.
"We need agriculture that doesn't just pursue maximum profit," Ehlers said. "There must be more focus on the interplay between agricultural yields and other ecosystem services."
Healthy soils, healthy foods
Building more sustainable agricultural practices benefits not only the environment, but also human health, said Swiss agriculture and development expert Han Herren. Recognized with the Alternative Nobel Prize Right Livelihood Award in 2013, Herren proposed that a variety of foods be cultivated.
"That would mean more and better crop rotation, resulting in fewer soil diseases, more microorganisms in the soil - and therefore healthier soil."