There
are many strategies that farmers, businesses, and consumers can adopt to reduce
greenhouse gases related to agriculture. First, farmers can replace fossil
fuels such as gasoline and diesel with biofuels such as ethanol or biodiesel.
Ethanol is a fuel alcohol that is produced by a fermentation process that uses
yeast to convert the sugars found in plants into a combustible alcohol fuel.
Ethanol can offset varying amounts of fossil fuel–generated carbon dioxide
depending on the material used to produce the ethanol. For example, Brazil,
located in a tropical climate, can efficiently grow sugarcane. Sugarcane is an
excellent source material for ethanol because the sugars in sugarcane can be easily
converted into alcohol. In the United States, corn is the primary feedstock for
ethanol. It is more costly to convert corn into sugar because the sugars are
bound up in long starch molecules. These carbohydrates must be broken down in
order to free up the sugars to be converted into alcohol. Therefore,
researchers in the United States are working hard to discover ways to lower the
costs of producing corn-based ethanol.
Researchers are also studying how to
use other plant materials to produce fuel. Cellulosic ethanol is not yet a
commercially-viable strategy, but many predict that it will be in the near future.
Cellulose is the fibrous or “woody” part of many plants. For example, high
concentrations of cellulose are found in the stock and leaves of corn. It would
be beneficial to use this part of the corn for ethanol production because it is
usually considered a waste product. Cellulosic ethanol would allow the corn
kernel to be used for food rather than as a source material for ethanol. The
challenge is that the sugars in the cellulose are tightly bound to starch
molecules. Consequently a more expensive, enzyme-driven process must be used to
convert the sugars into alcohol. Therefore, cellulosic ethanol is not
commercially viable now, but many countries, including the United States,
are
spending hundreds of millions of dollars to discover how it could become a
commercially viable fuel.
In addition to ethanol, research is
being conducted on other plant-based alcohol fuels such as methanol and butanol.
These fuels can also be produced from organic materials including grains and
wood fibers. They are currently not commercially viable, but some researchers claim
that they may be even better than ethanol as an alternative fuel. Diesel
produced from plant material can also reduce greenhouse gases. Crops known as oilseeds,
such as cottonseed, sunflower, soybeans, and canola, can serve as the source
material to produce a diesel product that has performance characteristics similar
to petroleum-derived diesel, without emitting the same volume of greenhouse
gases.
Farmers can also modify their
management practices so that farmland can serve as a sink to sequester carbon
dioxide. For example, farmers can create buffers comprised of trees, shrubs,
and natural grasses along rivers to prevent soil erosion and the loss of
nutrients due to runoff. The Conservation Reserve Program in the United States
pays farmers to take marginal cropland out of production as a way to reduce
soil erosion.
Farmers can also create windbreaks
near farmhouses and outbuildings. Windbreaks can create a microclimate that can
moderate temperature extremes by blocking cold winds or providing shade on hot summer
days. This can lower energy use and costs on farms. Windbreaks can also serve
as carbon sinks, whereby trees and other plants absorb carbon dioxide. Farmers
can also adopt conservation tillage strategies that leave part of the organic
residue on the field after the harvest. This material slows runoff, thereby
reducing soil erosion and nutrient loss. The decomposing material also
replenishes the nutrients in the soil. All of these practices can reduce the
energy used, and greenhouse gases produced, on the farm.
Livestock producers can reduce the
impact of their operations by changing how they manage animal waste such as
methane and manure. Some farmers are experimenting with anaerobic digesters
that convert manure into more manageable waste solids that can be used as an
organic fertilizer. The digester also creates methane as a byproduct, which can
be captured and used as a renewable fuel.
Finally, some writers argue for a
move away from large-scale industrial agriculture to place more emphasis on
so-called civic agriculture as a way to slow global warming. Civic agriculture
includes local food systems and organic foods. Local food systems reduce
greenhouse gases by reducing transportation costs. Traditional food supply
chains can stretch thousands of miles from the point of production to the place
of consumption. Local food advocates suggest that food could be grown and
consumed locally. Organic agriculture reduces the use of greenhouse gases
because organic farmers cannot use petroleumbased herbicides or pesticides.
BIBLIOGRAPHY.
Consultative Group on International
Agricultural
Research, www.cgiar.org (cited
September 2007);
Thomas Lyson, Civic
Agriculture: Reconnecting Farm, Food
and
Community (University
Press of New England, 2004);
Patrick Michaels and Robert
Balling, The Satanic Gases:
Clearing
the Air about Global Warming (Cato Institute,
2000); National Sustainable
Agriculture Information Service,
www.attra.ncat.org (cited September
2007); Monte
Oneal, et al., “Climate Change
Impacts on Soil Erosion
in Midwest United States with
Changes in Crop Management,”
Catena
(v.61, 2005); Organisation for
Economic
Co-operation and Development,
www.oecd.org (cited
September 2007); Agnes Sinai,
“China: The Sky Darkens,”
Le
Monde Diplomatique (April
2006); U.S. Department of
Agriculture, www.usda.gov (cited
September 2007); U.S.
Energy Information Administration,
www.eia.doe.gov
(cited September 2007); U.S.
Environmental Protection
Agency, www.epa.gov (cited
September 2007); Matthew
Wald and Alexei Barrionuevo, “The
Energy Challenge: A
Renewed Push for Ethanol, Without
the Corn,” New York
Times
(April 17, 2007); World Bank,
www.worldbank.org
(cited September 2007).
Christopher
D. Merrett
Western
Illinois University
Source: Encyclopedia of Global Warming and Climate Change (Click Here)
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