Civilizations Rise and Fall with Soil Quality: Dangers for Modern Agriculture

Civilizations rise and fall depending on the quality of their soil. With good farmland, cities and towns can flourish. Without it, though, they can easily fall. Now, scientists have revealed that the modern world could suffer a similar fate to past civilizations if soil quality degrades enough.

"Cultivating soil continuously for too long destroys the bacteria which convert the organic matter into nutrients," said Mary Scholes, one of the researchers, in a news release.

In the past, soil quality was a mystery to farmers. Traditional farmers spoke of soils becoming sick or tired or cold. The general response was to move on to another location until the land recovered. By the mid-20^th century, though, soils and plants would be routinely tested to diagnose deficiencies. Soon, companies began flooding soils with a soup of nutrients in order to keep them viable and productive.

In this latest study, the researchers pointed out that in the past, great civilizations have fallen because the failed to prevent the degradation of the soils on which they were founded.  Although we try to keep up with production by using modern techniques such as fertilizers, irrigating and plowing, these methods can only go so far. In fact, about one percent of global land area is degraded every year. In Africa, where much of the future growth in agriculture must take place, erosion has reduced yields by eight percent and nutrient depletion is widespread.

The problem is that while modern techniques can lead to an unprecedented increase in food production, they've also helped contribute to global warming and the pollution of water sources. Activities associated with modern farming are currently responsible for just under one third of greenhouse gas emissions, and more than half of these originate from the soil.

"Soil fertility is both a biophysical property and a social property--it is a social property because humankind depends heavily on it for food production," said Bob Scholes, one of the researchers, in a news release.

Modern agriculture doesn't just degrade water sources and add to greenhouse gas emissions, though. Replacing the fertility-sustaining processes in the soil with a dependence on external inputs has also made the soil ecosystem, and humans, vulnerable to interruptions in the supply of those inputs, for instance due to price shocks. That said, it's currently not possible to feed the current and future world population with an "organic" approach.

As the world's population continues to grow, it's necessarily to take soil erosion and efficient nutrient cycling into account. Without good soil, it's very likely that various cities and states could suffer.

The findings are published in the journal Science.