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The Highly-Hyped "No Regrets" Aspect of Carbon Sequestration Misses Its Real Significance
On 25 October 2001, the President and Board of Directors of the Soil Science Society of America released an official position paper on carbon sequestration.  It began by stating that "increased long term (20-50 year) sequestration of carbon in soils, plants and plant products will benefit the environment and agriculture."  Crop, grazing and forestlands, they said, "can be managed for both economic productivity and carbon sequestration," adding that in many settings "this dual management approach can be achieved by applying currently recognized best management practices such as conservation tillage, efficient nutrient management, erosion control, use of cover crops and restoration of degraded soils," as well as by "conversion of marginal arable land to forest or grassland."

Although the stimulus for this statement may well have been the current worldwide concern over model-predicted CO2-induced global warming, soil scientists are well acquainted with the many real-world benefits of beefing up the organic matter content of the planet's soils, which knowledge makes this approach to the putative problem much more than a mere "no regrets" policy, for it is clearly a shining virtue in its own right.

"Increases in soil organic carbon," the Society says in its official statement, "generally improve soil structure, increase soil porosity and water holding capacity, as well as improve biological health for a myriad of life forms in soil."  Recommended agronomic, grazing land and forestry practices, they say, "also enhance land sustainability, wildlife habitat and water quality."  In addition, the Society notes that these practices "result in decreased water and wind erosion."

Perhaps the best statement we have ever seen on the subject (and one of the world's longest sentences) comes from Wallace (1994), who said soil organic matter "stops soil erosion, it supplies nutrients, it is a buffer against pH change, it holds water, it increases the cation exchange capacity which protects against leaching loss of nutrients, it decreases compaction, it stores nutrients from season to season, it makes soil warmer in the spring, it makes soils easier to till especially when slightly too wet, it makes inputs more valuable, it protects against plant diseases, it gives better aerated more permeable soil, it protects against heavy metal and salt toxicities, it detoxifies pesticides and prevents their leaching, it is a storage mechanism for excess atmospheric CO2, it gives high yields, it promotes microbial breakdown of toxic substances, it makes it possible to grow acid loving plants, it supports microorganisms that recycle nutrients, and it promotes soil formation."

It is also important to note that the ongoing rise in the air's CO2 content brings about these same desired consequences, as it stimulates planet-wide vegetative growth, which results in more organic matter being added to the world's soils.  In discussing the impacts of this phenomenon on tropical and subtropical agriculture, for example, Sombroek et al. (1993) say "the CO2 fertilization effect is likely to have a significant impact on plant growth in the humid tropics in a CO2 enriched atmosphere, yielding extra soil organic matter through litterfall and crop residues, and especially through a more vigorous root growth ...  The CO2 antitranspiration effect would be of particular significance in the semiarid regions of the tropics and subtropics: plants would grow more vigorously with the same amount of water, and some plant growth would become possible where hitherto the land surface [has been] bare, due to climate- or salinity-induced hazards, lowering the soil-surface temperatures and providing fresh organic matter for incorporation in the soil."

Even if climate model scenarios of serious-to-catastrophic global warming are wrong, therefore, the sequestering of more carbon in the world's soils is a laudable goal; and all reasonable efforts should be made to promote - but not force or unfairly subsidize - this worthy enterprise, especially in light of the fact that the growing population of the planet continues to put ever more pressure on the natural resources required to meet human food needs.  This should, in fact, be the one policy initiative upon which all parties on both sides of the CO2-climate debate can agree.  Those who worry about global warming should embrace the initiative because of the great potential for carbon sequestration to slow the rate of rise of the air's CO2 content; while those who do not believe in the worrisome climate change predictions should find the policy agreeable because increasing the organic matter content of the world's soils is simply the right thing to do, given its host of beneficial impacts on the environment and the natural resource base that sustains the entire biosphere.

Perhaps we could all, as the Beatles once sang, "come together, right now," over this one important means of bettering earth's environment and increasing the planet's capacity for sustaining its many forms of life.  We're for it.  How about you?

Dr. Sherwood B. Idso Dr. Keith E. Idso

References
Sombroek, W.G., Nachtergaele, F.O. and Hebel, A.  1993.  Amounts, dynamics and sequestering of carbon in tropical and subtropical soils.  Ambio 22: 417-426.

Wallace, A.  1994.  Soil organic matter is essential to solving soil and environmental problems.  Communications in Soil Science and Plant Analysis 25: 15-28.