To see what can happen to civilizations that lost the topsoil they needed to grow food, look no further than Syria or Libya. Roman tax records show that those areas grew ample amounts of wheat, but as farmers continued to plow their fields, they exposed valuable microbes and topsoil eroded. Today those areas barely have any soil to grow crops.
“Societies that lose their topsoil, their descendants pay the price,” Montgomery says. “Nature takes a long time to build soil.” By some estimates, it can take 500 years for healthy topsoil to develop and less than a century to degrade.