Limited Biofuel Feedstock Supply?November 29, 2007The United States has embarked on an ambitious program to develop technology and infrastructure to economically and sustainably produce ethanol from biomass. Corn stover, the above-ground material left in fields after corn grain harvest, has been identified as a primary feedstock. Stover and other crop biomass or residue is frequently referred to as "trash" or a waste, implying it has minimal value. However, when returned to the land, this carbon-rich material helps control erosion, replenishes soil organic matter, and improves soil quality. Organic matter in the soil retains and recycles nutrients and improves soil structure, aeration, and water exchange characteristics. In addition, organic matter is the energy source for the soil ecosystem. "Sustainable biofuel production will require that the functions of organic matter in the soil be addressed before crop residue is removed from the land," states Doug Karlen, USDA-ARS soil scientist at the National Soil Tilth Laboratory at Ames, IA. Dave Lightle, USDA-NRCS agronomist with the National Soil Survey Center in Lincoln, NE says, "To date, projected sustainable harvest levels have been calculated by reducing total stover production by amounts needed to keep soil erosion losses within accepted limits." Most estimates of the amount of crop residue that can be sustainably harvested consider only erosion as a constraining factor, without considering the need to maintain soil organic matter. Recently Jane Johnson and her coworkers at the USDA-ARS North Central Soil Conservation Research Laboratory at Morris, MN, reported estimates of the minimum biomass input needed to maintain soil organic matter. Wally Wilhelm, USDA-ARS scientist with the Agroecosystems Management Research Unit, Lincoln, NE, and his team compared the amount of stover needed to replenish soil organic matter and control water and wind erosion under a limited number of production conditions-continuous corn and corn produced in rotation with soybean with moldboard plow or conservation tillage practices. The amount of stover needed to replenish soil organic matter was greater than that required to control either water or wind erosion in the ten counties (in nine of the top eleven corn production states in the U.S.) investigated. This outcome emphasizes the need to further evaluate the validity of widely circulated estimates of U.S. cropland capacity to sustainably supply feedstock for the emerging cellulosic ethanol industry. The article appears in the November-December 2007 issue of Agronomy Journal and was the basis of a poster presentation titled "Soil Carbon Needs Limit Biomass Ethanol Feedstock Supply" at the 2007 American Society of Agronomy meetings in New Orleans in November 2007. This research contributes to the USDA-ARS Renewable Energy Assessment Project (REAP) goals and was funded by the USDA-ARS and USDA-NRCS agencies. The authors conclude that there is a critical need to gather additional high-quality replicated field data from multiple locations to confirm their calculations and to expand the computations to a broader range of cropping systems before major decisions are made about the percent of stover that can designated for biomass energy production. In addition, they state that an extensive effort is needed to expand development of existing crops, discover and develop unconventional crops, and create and deploy advanced cropping systems that exploit the potential of all crops so that biomass production can be greatly expand to provide a sustainable supply of cellulosic feedstock without reducing soil organic matter, thus undermining the productive capacity of the soil. The article is available for 30 days free access at the Agronomy Journal website, http://agron.scijournals.org. View the abstract of this research at: http://agron.scijournals.org/cgi/content/abstract/99/6/1665 Agronomy Journal is a peer-reviewed, international journal of agronomy published six times a year by the American Society of Agronomy. The American Society of Agronomy (ASA) www.agronomy.org, is an educational organization helping its 8,000+ members advance the disciplines and practices of agronomy by supporting professional growth and science policy initiatives, and by providing quality, research-based publications and a variety of member services. American Society of Agronomy |
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| Related Organic Matter Current Events and Organic Matter News Articles DNA barcodes: Creative new uses span health, fraud, smuggling, history, more The scientific ability to quickly and accurately identify species through DNA "barcoding" is being embraced and applied by a growing legion of global authorities - from medical and agricultural researchers to police and customs authorities to palaeontologists and others. Organic weed control options for highbush blueberry Research scientists at Nova Scotia Agricultural College have been working steadily to find effective organic methods to control weeds in cultivated blueberry crops. Climate variability impacts the deep sea Deep-sea ecosystems occupying 60% of the Earth's surface could be vulnerable to the effects of global warming warn scientists writing in the Proceedings of the National Academy of Sciences. Designer molecule detects tiny amounts of cyanide, then glows A small molecule designed to detect cyanide in water samples works quickly, is easy to use, and glows under ultraviolet or "black" light. Arctic land and seas account for up to 25 percent of world's carbon sink In a new study in the journal Ecological Monographs, ecologists estimate that Arctic lands and oceans are responsible for up to 25 percent of the global net sink of atmospheric carbon dioxide. Key new ingredient in climate model refines global predictions For the first time, climate scientists from across the country have successfully incorporated the nitrogen cycle into global simulations for climate change, questioning previous assumptions regarding carbon feedback and potentially helping to refine model forecasts about global warming. Mystery Solved: Marine Microbe Is Source of Rare Nutrient A new study of microscopic marine microbes, called phytoplankton, by researchers at Woods Hole Oceanographic Institution (WHOI) and the University of South Carolina has solved a ten-year-old mystery about the source of an essential nutrient in the ocean. Help Students Think like Soil Scientists Emphasizing cross-disciplinary concepts in teaching soil science courses, such as mass-volume relationships, can help undergraduates learn real-world, problem-solving skills that are crucial to their success in soil science careers. Golf course putting greens show their age Just like the rest of us, golf courses show their age-especially on putting greens, which experience more foot traffic than anywhere else on golf courses. Putting greens, which comprise only about 1.6% of the total area on most courses, require more intensive management than any other part of the course. Perennial vegetation, an indicator of desertification in Spain A team of scientists has analyzed 29 esparto fields from Guadalajara to Murcia and has concluded that perennial vegetation cover is an efficient early warning system against desertification in these ecosystems. The study has been published in the Ecology magazine. More Organic Matter Current Events and Organic Matter News Articles |
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