Soil

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Bioenergy > Environmental issues > Agriculture > Soil

Womens farming cooperative members work to remove weeds by hand from the soil of their rice plot in Madagascar

Issues

Soil amendments

• Charcoal (char) can be used as a soil amendment to enhance soil fertility.
• Remineralization, the introduction of powered rock and minerals, can enhance soil fertility.

Soil carbon sequestration

• Soil is the second largest sink for carbon (after the oceans)
• News:
  • A dirty way to fight climate change - 29 November 2007 by Steven I. Apfelbaum and John Kimble on Yahoo News: The authors recommend the sequestration of carbon in soils, which they describe as "one of the most overlooked yet most effective and inexpensive strategies available." They also advise that trees should not be planted where they may reduce the volume of carbon stored in the soil, such as lands that formerly were prairies or wetlands; "deep-rooted grassland or wetland plants, which sequester carbon more effectively than trees do" should be planted instead. Soil carbon can also be enhanced through "no-till" farming.
    • The authors conclude that "Scientific analyses show that recapturing atmospheric carbon into soil and plant communities is the easiest and least expensive method for mitigating climate change and that it provides many other economic, cultural, and ecological benefits. Restoring soils in currently farmed land can rein in 10 to 15 percent of the annual carbon emissions Americans create. Replanting native grasslands and restoring drained wetlands can reduce up to another 20 percent....These techniques can also produce usable bioenergy crops, food, and fiber supplies. This enables energy, food, and commodities to be produced locally, thus reducing transportation and distribution costs and their associated carbon emissions."
• Organizations:
  • Consortium for Agricultural Soils Mitigation of Greenhouse Gases (located at Colorado State University, Colorado) - "CASMGS is a consortium of nine universities and one National Laboratory assembled to investigate the potential of agricultural soils to mitigate greenhouse gases."[1]
  • Soil Carbon Center at Kansas State University (Kansas)
• Events:
  • 17-18 December 2007, Manhattan, Kansas: CASMGS Forum: Agriculture's Role in the New Carbon Economy
• Resources:
  • FAO Soil Carbon Sequestration Background page
  • Wikipedia article on soil carbon

Soil erosion

Soil organic matter

News:

• Can Dirt Really Save Us From Global Warming?, 3 September 2009 by NPR: "This month the Senate is set to take up the climate and energy bill that Congress began work on last spring. One provision will likely set up a system to pay farmers for something called 'no-till farming.'"
  • "The concept: When crops are planted without tilling, the soil holds more carbon, which means less goes up into the atmosphere."
  • "But scientists aren't sure no-till really sequesters carbon any better than conventional farming....Researchers have discovered that when you dig down three feet or so, plowed fields hold just as much — if not more — carbon than no-till."
  • "There's a possible conflict brewing here, though. Federal law and the energy bill encourage farmers to remove crop residue — the remains of the previous season's crop — to make ethanol."
  • "'That's a no-no,'" soil scientist Rattan Lal says. "'The moment you take the crop residue away the benefit of no-till farming on erosion control, water conservation and on carbon sequestration will not be realized.'"(Audio also available)

• Crop Residue May Be Too Valuable to Harvest for Biofuels, 15 July 2008 press release by Washington State University: "In the rush to develop renewable fuels from plants, converting crop residues into cellulosic ethanol would seem to be a slam dunk. However, that might not be such a good idea for farmers growing crops without irrigation in regions receiving less than 25 inches of precipitation annually, says Ann Kennedy, a USDA-Agricultural Research Service soil scientist".
  • "If residue were harvested, she said, soil fertility would drop and farmers would have to find other ways to increase the amount of organic matter in their soils."
  • "'We need to constantly replenish organic matter—so removing valuable residue, especially in areas with low rainfall, may not be the best practice.'"[2]

Publications

• Soil Carbon Sequestration in U.S. Rangelands Issues Paper for Protocol Development (PDF) by the Environmental Defense Fund. This reports looks at issues such as agriculture, emissions offsets, grasslands, increased carbon sequestration, and soil.

• Soil Carbon Management: Economic, Environmental and Societal Benefits

Scientific papers

• The Environmental Benefits of Cellulosic Energy Crops at a Landscape Scale, 3 May 1996, by Robin L. Graham, et al, finds that "growing biomass energy crops can enhance soil fertility or degrade it."[3]. The particular contribution to soil fertility depends on a number of related factors.

News

• Land Use Offers Valuable Solutions for Protecting the Climate, 7 July 2009 by SolveClimate: "It’s well-known that the trick to reducing net carbon emissions relies on not emitting so much of the stuff and finding a way to get it back where it belongs....That’s where the land comes in. Thirty percent of greenhouse gases come from 'the land-use sector.'...So let's talk farming. Let's talk trees. And let's talk land degradation."
  • "That’s the argumentative thread running through the [Worldwatch] Institute's newest report, Mitigating Climate Change through Food and Land Use, by Sara J. Scherr and Sajal Sthapit."
  • "The first step is simply realizing the magnitude of agricultural or forestry-based contribution to emissions and, potentially, to absorption."
  • "Carbon dioxide and other greenhouse gases also seep into the atmosphere as the secondary effects of land-use changes. Exposed soil erodes more easily, and oxidizes more readily, releasing carbon dioxide into the atmosphere, while nitrogen fertilizers cause soil to emit nitrous oxide, an enormously potent greenhouse gas. The gist is that land-use change is a big problem—close to a third of the problem."[4]

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