cover image Dirt: The Erosion of Civilizations

Dirt: The Erosion of Civilizations

David R. Montgomery, . . Univ. of California, , $ 24.95 (304p) ISBN (285pp) ISBN 978-0-520-24870-0

Montgomery (King of Fish ), a geomorphologist who studies how landscapes change through time, argues persuasively that soil is humanity's most essential natural resource and essentially linked to modern civilization's survival. He traces the history of agriculture, showing that when humans exhausted the soil in the past, their societies collapsed, or they moved on. But moving on is not an option for future generations, he warns: there isn't enough land. In the U.S., mechanized agriculture has eroded an alarming amount of agricultural land, and in the developing world, degraded soil is a principal cause of poverty. We are running out of soil, and agriculture will soon be unable to support the world's growing population. Chemical fertilizers, which are made with lots of cheap oil, are not the solution. Nor are genetically modified seeds, which have not produced larger harvests or reduced the need for pesticides. Montgomery proposes an agricultural revolution based on soil conservation. Instead of tilling the land and making it vulnerable to erosion, we should put organic matter back into the ground, simulating natural conditions. His book, though sometimes redundant, makes a convincing case for the need to respect and conserve the world's limited supply of soil. Illus. not seen by PW . (May)