The Future of Dirt by Drake Bennett

Today's Boston Globe, at Boston.com has a fascinating opinion article about a rapidly depleting resource: soil. Take the time to click on the link below to read the entire article. It is well written, referenced and thought provoking.

"The Future of Dirt" by Drake Bennett
Highlights -
-oil reserves and dwindling freshwater supply may get all the attention, but modern society is also overtaxing the ground itself.

An increasing number of scientists are starting to emphasize the extent to which soil - even more than petroleum or water or air - is a limited and fragile resource.

Scientists in Australia and the United States have started making rich new earth from industrial waste, and research into the astonishing fertility of a mysterious Amazonian soil may lead to an additive that can boost the power of soil for thousands of years.

Dirt remains, in certain ways, a puzzle: Despite its seeming simplicity, it is a complex system whose fertility arises from the interaction of myriad physical, biological, and chemical properties.
It takes tens of thousands of years to make 6 inches of topsoil.

Because of all the things human beings do to it, University of Washington geologist David Montgomery has calculated, the world today is losing soil 10 to 20 times faster than it is replenishing it.

However, it has also happened that civilizations have improved their dirt. Among the world's richer soils is terra preta, the "black earth" found in certain swaths of the Amazon basin. It is dark, loose, and loamy, and unlike the pallid earth that characterizes most of the Amazon, it is strikingly fertile.
In the last few years, archeologists have established something else intriguing about terra preta: it is man-made. It contains high concentrations of charcoal, along with organic matter such as manure and fish bones - essentially the household trash of a pre-Columbian society practicing a distinctive brand of slash-and-burn agriculture.

The challenge is to make truly synthetic soil that matches the stability and longevity of natural topsoil. (The artificial soils sold by the bag at gardening stores tend to be either natural soil that has been enriched, or potting soil, which is mostly compost and quickly degrades.)

Dick Haynes, a soil scientist at Australia's University of Queensland, has created a synthetic soil from industrial waste products: fly ash from power plants and byproducts of aluminum processing for its mineral components, poultry litter and manure for its organic matter.

Until such methods are within reach of farmers, soil experts are focusing on ways that farmers can protect and even improve the soil they have.

One example is crop rotation, an ancient farming practice now seeing more use in both the developed and developing world. Instead of watching soil blow away from fallow fields between plantings, farmers are alternating grain crops with other crops so that the soil is covered at all times. And if those other crops are legumes like alfalfa, clover, or soybeans, they also take nitrogen out of the air and enrich the soil.

Another technique is to persuade farmers to stop tilling their ground entirely. Tilling, or plowing, is for most people synonymous with farming - traditionally it's been used to control weeds and mix fertilizer into the soil. But it also leaves soil far more susceptible to erosion, drying it out and leaving it bare to wind and rain.
To combat this, a growing number of American farmers are adopting "no-till" techniques, using machinery that inserts seeds through small slits into the ground. After the harvest, the crop remains are left on the field to decay, replenishing the soil in ways that synthetic fertilizers cannot.

To soil scientists, the time horizon is only part of the political challenge. The larger problem may be, simply, that it remains hard for many people to take soil seriously.

Caring properly for soil, whether through additives like biochar or techniques like crop rotation and no-till agriculture, may have a serious role to play in mitigating greenhouse gases.

"Maintaining your soil quality," says Laird, "is maintaining the viability of your society."
Drake Bennett is the staff writer for Ideas. E-mail drbennett@globe.com.