Thursday, November 29, 2007

Farming , and Global Warming, and the restoring of grasslands.

More people are beginning to realize how global warming represents an unparalleled opportunity for us to address poverty, inequality, and conflict, and revitalize our industrial base and infrastructure while switching to energy sources that do not add carbon to the atmosphere. But there is also a huge opportunity in transforming our land management so as to increase soil organic matter, which may be the only rapid, practical, and economic way to reduce atmospheric carbon.

The 2012 farm bill could provide major motion in this direction, while achieving most of the other goals that have come up around the farm bill in past cycles. Instead of a politics of win/lose, of scarcity and zero sum, we would need a politics that addresses causes rather than symptoms and creates multiple, interlocking benefits.

Soil organic matter

Often called humus, soil organic matter is usually about 58 percent carbon by dry weight. Plants capture carbon from the atmosphere through photosynthesis. This plant material, traveling through complex food webs both above and below ground, is broken down and eventually some of it forms soil organic matter.

In temperate zones, this soil organic matter can last for generations, unless it is exposed to air and microbes that can rapidly oxidize the carbon into atmospheric carbon dioxide. This reaction is much like combustion: carbon and oxygen are combined into carbon dioxide, releasing energy.

In tropical areas, soil organic matter tends to oxidize more rapidly because of the higher temperatures.

Perennial grasslands in temperate zones have the greatest capacity to form and store soil carbon. Much of these black, carbon-rich prairie soils were plowed in the last two centuries and have released much of their carbon into the atmosphere. In the last generation or two, alternative agriculture practitioners on all continents have discovered how to restore organic matter to their soils through management. A key principle is to keep the soil covered with plants and plant material, which feeds the soil microbes that create humus.

The methods of increasing soil organic matter have been well demonstrated by various practitioners of alternative agriculture, including managed grazing, pasture cropping, no-till, and organic. No new technology is required. With soil organic matter as the primary direction of our farm policy, we would:

Take excess carbon out of the atmosphere, where it is dangerous, and put it back in the soil where it belongs, and where it will enhance every aspect of our lives. Much of the carbon dioxide in the atmosphere has been released from our soils via tillage, chemical applications, and exposure (and it's still going on). In the atmosphere, this carbon contributes to greenhouse warming. If we can get it back into the soil, using free solar energy, we will be able to grow food with fewer inputs and stabilize our climate.

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