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 News Articles Rising energy, food prices major threats to wetlands as farmers eye new areas for crops Critical food shortages and growing demand for bio-fuels and hydro-electricity due to high fossil fuel prices rank among the greatest threats today to the preservation of precious wetlands worldwide as farmers and developers look for new areas for agriculture, energy crop plantations and hydro dams. Microbes beneath sea floor genetically distinct Tiny microbes beneath the sea floor, distinct from life on the Earth's surface, may account for one-tenth of the Earth's living biomass, according to an interdisciplinary team of researchers, but many of these minute creatures are living on a geologic timescale. Brown papers reveal widespread, hardworking water on ancient Mars For decades, scientists have theorized - romanticized, even - that Mars has harbored water. The evidence has grown stronger as recent missions to the Red Planet have revealed in stunning detail Martian topography, mineralogy and clues to past climate. But how much water, where it was or is located and what it was doing have been hard to pin down. New Findings Show Diverse, Wet Environments on Ancient Mars Mars once hosted vast lakes, flowing rivers and a variety of other wet environments that had the potential to support life, according to two new studies based on data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and other instruments on board NASA's Mars Reconnaissance Orbiter (MRO). Iowa State researchers study ground cover to reduce impact of biomass harvest Ground cover may be one workable method to reduce the effects of erosion that future biomass harvests are predicted to bring. Fungi the cause of many outbreaks of disease but mostly ignored Fungi can cause a number of life-threatening diseases but they also are becoming increasingly useful to science and manufacturing every year. Laser fluorescence could find life on Mars A team of scientists from the United States and the United Kingdom has developed a technique using ultraviolet light to identify organic matter in soils that they say could be used to document the existence of life on Mars. Pacific coast turning more acidic An international team of scientists surveying the waters of the continental shelf off the West Coast of North America has discovered for the first time high levels of acidified ocean water within 20 miles of the shoreline, raising concern for marine ecosystems from Canada to Mexico. Global warming will negatively impact tropical species Global warming is likely to reduce the health of tropical species, scientists from UCLA and the University of Washington report May 6 in Proceedings of the National Academy of Sciences. 65-million-year-old asteroid impact triggered a global hail of carbon beads The asteroid presumed to have wiped out the dinosaurs struck the Earth with such force that carbon deep in the Earth's crust liquefied, rocketed skyward, and formed tiny airborne beads that blanketed the planet. More Organic Matter News Articles |
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