Daniel Richter of Duke University said humans have changed the dirt under their feel to a point that this could be referred to as the "Anthropocene (or man-made) Age," the university said Friday in a release.

Richter said more than than half of all soils on Earth are being cultivated for food crops, grazed or periodically logged for wood.

A report on the issue is published in the journal Soil Science.

"Society's most important scientific questions include the future of Earth's soil," Richter said in a statement. added. "Can soils double food production in the next few decades? Is soil exacerbating the global carbon cycle and climatic warming? How can land management improve soil's processing of carbon, nutrients, wastes, toxics and water, all to minimize adverse effects on the environment?"

Richter said there is concern that agriculture has so degraded regional soil fertility in Africa that the economic development of whole nations will be diminished without drastic improvements of soil management.