Precious dirt

About 200 years ago, Europe saw a major increase in the number of people leaving the countryside for towns and cities. Europeans flocked to cities hoping to end poverty and find better livelihoods than they could in rural villages and homesteads.

Those are still the main reasons people move to urban areas today, especially in developing countries where urbanization started later than it did in Europe. Half of the world's population lives in cities. But this trend has had devastating effects on the arable land around cities, with no small impact on people.

"The problem is that cities have been built on fertile land," said Klaus Lorenz, a biologist at the Institute for Advance Sustainability Studies in Potsdam. "People settled in places where food could be grown. Now if you start to expand the cities, this fertile land is being destroyed and the soil is lost for food production."

Concrete jungles

Global Soil Week in Berlin aimed to take on such problems. Scientists, government representatives and members of civil society met last week to share their experiences with the land and work on sustainable soil management and governance.

About 1,000 square kilometers of land are lost every year in Europe because of urbanization and construction and recovering the dirt is hard work.

"If you urbanize a region, about 50 percent of the soil will be covered by non-permeable materials like concrete or asphalt," said Lorenz. "The soil cannot be used in any other form once it has been covered up."

The program at Global Soil Week, which was funded by the German Education Ministry and other German groups, included a variety of expert panels and a film festival on the topic.

Developing countries overlooked

But participants like Clistenes Nascimento of the University of Pernambuco in Brazil said they felt the event did not focus enough on developing countries and emerging economies.

"We have to reorganize the way people use their land and occupy their land," he said of Brazil, "because few cities had an urbanization plan."

Nascimento added that soil pollution is one of the worst effects of urbanization in Brazil, while landslides cause many problems, too. He said he felt Brazilians are not aware of how precious the soil is.

In China, where dozens of cities with million of inhabitants are under construction, soil acidification is a growing problem.

Guanzhou is China's third largest city, with an estimated 16 million inhabitants living over about 10,000 square kilometers. Rapid industrialization there has caused soil pollution and other problems. Now people are trying to clean industrial wasteland from hazardous substances to utilize it for new purposes. But one difficulty is a lack of regulations for soil remediation in China.

Call to raise awareness

With urban expansion such a big problem around the world, it might make sense to build cities vertically. But Lorenz pointed out that's not an option for cities in earthquake zones like Mexico City. Instead, he called for cities to make better use of free urban spaces, through methods like green roofs and urban farming.

Lorenz added that while Global Soil Week was chiefly aimed at politicians, consumers should also become more aware of problems connected with soil.

"We are simply too far away from the products on our tables," he said. "We're far away from making the connection that arable soil was necessary to produce this food. And that we simply cannot produce soil. That is impossible. Natural, fertile soils - if they are gone, they are gone."