NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665
February 17, 2000
Environmental concerns about greenhouse-gas emissions is fueling an international debate on how to reduce and otherwise manage these heat-trapping gases. One potential outcome of this debate is that the region's farmers may benefit financially from adapting new agronomic practices aimed at increasing the organic matter content, and subsequently the carbon content, of soils--a process called carbon sequestration.
"The content of organic matter is about 45 percent carbon," says Dave Franzen, a soils specialist with the North Dakota State University Extension Service. "A 1-percent change in a soil's organic-matter content is equivalent to about 4 to 4.5 tons of carbon per acre."
NDSU researchers are involved in efforts to determine how quickly and how much carbon can be stored in soil, for how long and in which forms. Answers to these questions will prove useful as energy companies and other businesses seek short-term solutions for managing greenhouse-gas emissions.
What's Agreed Upon, What's Debatable
Greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide and ozone. Carbon dioxide is released into the atmosphere by the burning of materials such as solid waste, fossil fuels (oil, natural gas and coal), wood and wood products.
"There is no debate in the science of the greenhouse-gas effect," says James Hrubovcak, an economist with the USDA's Global Change Program office in Washington, D.C. "It's just very, very difficult to say what that means in terms of temperature changes, precipitation changes (and) the variability of extreme events. There's so much unknown about how ecosystems work... That's where it becomes more speculative."
The international climate-change agreement reached at Kyoto, Japan, in December 1997 set binding targets for reducing greenhouse-gas emissions during the first commitment period running from 2008 through 2012. According to a fact sheet developed by the Bureau of Oceans and International Environmental and Scientific Affairs, the specific targets in the Kyoto Protocol vary from country to country, but those for the European Union, the United States and Japan are similar--namely, a reduction of 8 percent below 1990 emission levels for the EU, 7 percent for the United States and 6 percent for Japan. However, the Senate must first ratify the Kyoto Protocol before the United States becomes bound by it.
Emissions Trading: A Short-Term Solution
As part of the Kyoto Protocol, countries, energy consortiums and individual businesses can engage in emissions trading by buying less expensive permits (credits) from countries that have more credits than they need. In addition, the Kyoto Protocol allows activities that absorb carbon to be offset against emissions targets. Carbon-absorbing activities include planting trees in forests and unforested areas and adopting conservation tillage practices on farmland. Reforested areas, tree plantings in previously unforested areas and farmland rich in organic matter content are known as carbon "sinks," explains a Bureau of Oceans and International Environmental and Scientific Affairs fact sheet.
"It's unclear what role carbon sequestration will play under the Kyoto Protocol. These things are not worked out yet, but that has not prevented some trades from taking place," Hrubovcak says.
For example, the Greenhouse Emissions Management Consortium (GEMCo), based in Vancouver, British Columbia, Canada, recently purchased carbon emission reduction credits from a group of Iowa farmers. GEMCo is a consortium of Canadian power utilities, and it contracted with these farmers by working with two intermediaries, IGF Insurance and CQuest Ltd. The Iowa farmers will receive between $3 and $15 an acre for adopting carbon-sequestering practices such as conservation tillage, according to Aldyen Donnelly, GEMCo president.
How much the Iowa farmers get paid depends to some extent on when they "deliver"--when they've logged six continuous years in a conservation tillage practice. GEMCo has invested in Canadian research to determine the range of carbon gain that might be realized when farmers shift to more sustainable land-use practices, Donnelly says, and it is this research that GEMCo has relied on for drafting its contracts.
What's Known, What's Not
"Under most conditions, no-till farming can sequester about 300 pounds of carbon per acre per year--up to a point--but we don't know what that point is," says Larry Cihacek, an NDSU soil scientist. "From what I know about soils, within about six years we're going to reach an equilibrium. We'll not be able to store much carbon after that point unless we do something different in the way we manage soils."
Cihacek has represented NDSU at three international symposiums focusing on carbon sequestration. Besides representatives from several U.S. agencies and Cabinet-level departments, the symposiums have also been attended by scientists and government officials from about 20 other countries, including Brazil, India and Mexico, as well as Canada, Great Britain, Australia and New Zealand.
Research shows that climate, cropping system and soil type determine how much carbon can be sequestered, Cihacek says. Most carbon, in its organic form, would be stored in the top 6 inches of the soil profile, the area where the soil is most dynamic due to microbial activity and other factors. As a result, this organic carbon is unstable and more easily released back into the atmosphere than organic carbon stored deeper or inorganic carbon which binds with free calcium in soil to form calcium carbonate (lime), a solid.
"We need to look at storing carbon deeper than 1 foot. We should be looking at storing carbon 3 feet deep in the soil profile, which is still within the root zone of many crops grown in this region," Cihacek says. "We can probably store some carbon deep, but research thus far shows that this may be a factor of soils and environment. It looks as if we need free calcium and significant freezing of soils to store inorganic carbon."
North Dakota Results
Research conducted in North Dakota in the mid-1990s by NDSU and the Natural Resources Conservation Service (NRCS) showed that the amount of organic carbon stored in native grassland could be about 32 tons per acre greater than what's being stored in a long-term crop-fallow system. But, Cihacek says, subsequent studies indicate that carbon losses due to tillage may have been overstated because tillage compacts the soil, and the density of tilled soil mitigates carbon loss. Later research also showed that total carbon stored to the 3-foot level remained within a similar range regardless of whether the soils had been tilled or left in native grassland.
In another study investigating the effects of tillage on inorganic carbon, NDSU and NRCS researchers found that when soils freeze, the calcium salts the soils contain precipitate, a process that causes the calcium to bond with dissolved carbon dioxide and form inorganic carbon. Because grassland vegetation can trap more insulating snow than cropland or fallow fields, grassland will not freeze to the same depth as cropland, and more inorganic carbon can accumulate in cropland. This phenomenon may explain why tillage has less effect on carbon loss than soil scientists originally thought.
Where to from Here
NDSU and NRCS researchers are beginning a new project that looks at historic soil-test data in North Dakota and the Minnesota side of the Red River Valley. Cihacek and his colleagues will estimate how much carbon is currently stored in these soils and how much it changes during the study period. To make a comparison against the historic data, they plan to monitor annual soil tests for organic matter content and take soil bulk-density samples to calculate soil carbon change.
"In my opinion, we should be able to use a standard soil test and a bulk density sample to determine how much carbon is being stored by changing farming practices," Cihacek says.
Both Cihacek and Franzen wonder what farmers who've been practicing no-till and other forms of conservation tillage will do if their neighbors start getting paid for what they've already been doing. Franzen says some farmers already practicing conservation tillage may consider switching to conventional tillage to become eligible for payments when they switch back to conservation tillage.
Meanwhile, the Kyoto Protocol is unlikely to be voted on by the Senate until after the presidential election. So for the short-term, the issue of carbon sequestration is likely to be decided by the marketplace. Cihacek says farmers interested in changing their farming practices so they can receive payments for sequestering carbon should seek information from businesses such as insurance companies, as well as from farm organizations and government agencies. He concludes, "Right now, there's not much of a structure in place for making this decision."
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Sources: Larry Cihacek (701) 231-8572
Dave Franzen (701) 231-8884
Editor: Dean Hulse (701) 231-6136