Featured Research

from universities, journals, and other organizations

Replacing Corn With Perennial Grasses Improves Carbon Footprint Of Biofuels

Date:
December 5, 2008
Source:
University of Illinois at Urbana-Champaign
Summary:
Converting forests or fields to biofuel crops can increase or decrease greenhouse gas emissions, depending on where -- and which -- biofuel crops are used, researchers report.

Converting agricultural land to perennial grasses, such as Miscanthus, has a beneficial effect on soil carbon.
Credit: Photo by Don Hamerman

Converting forests or fields to biofuel crops can increase or decrease greenhouse gas emissions, depending on where – and which – biofuel crops are used, University of Illinois researchers report.

Related Articles


The researchers analyzed data from dozens of studies to determine how planting new biofuel crops can influence the carbon content of the soil.

Plants use the sun's energy to convert carbon dioxide from the atmosphere into the organic carbon that makes up leaves, stems and other plant parts. As plants decay, this carbon goes into the soil. Organic carbon is an important component of soil health and also influences atmospheric carbon dioxide levels. Whenever the soil is disturbed, as occurs when land is plowed or cleared of vegetation, some of this carbon returns to the atmosphere in the form of carbon dioxide.

"From the time that John Deere invented the steel plow, which made it possible to break the prairie sod and begin farming this part of the world, the application of row crop agriculture to the Midwest has caused a reduction of soil carbon of about 50 percent," said Evan DeLucia, a professor of plant biology at Illinois and corresponding author on the new study.

Any debate on the environmental consequences of using plants to produce liquid fuels should also consider how each option affects soil carbon, DeLucia said.

"The biggest terrestrial pool of carbon is in the soil. The top meter of soil holds more than three times the amount of carbon stored in either vegetation or the atmosphere, so if you do little things to change the amount of carbon in the soil it has a huge impact on the atmosphere and thus global warming."

Unlike corn, which must be replanted every year, perennial grasses such as switchgrass and Miscanthus preserve and increase carbon stores in the soil. These and other grasses have been proposed as high-energy alternative feedstocks for biofuel production.

Currently, ethanol is produced by fermenting the starch in corn kernels, but significantly more liquid fuel energy can be harvested from the stems and leaves of plants. The technology for producing this "cellulosic" ethanol is still quite expensive, but many believe that it will displace corn ethanol as the technology advances.

About 20 percent of the corn crop currently goes into ethanol production in the U.S., DeLucia said, "so we began with the hypothesis that it might be good for soil carbon to put a perennial biofuel crop on the landscape instead of corn."

The researchers analyzed published estimates of changes in soil organic carbon in landscapes converted from natural or agricultural land to biofuel crops. They focused on corn, sugar cane, Miscanthus, switchgrass and native prairie grasses. They also evaluated the impact of harvesting and using corn stover (the plant debris left over after corn is harvested) as a cellulosic biofuel source.

Their analysis showed that converting native land (grassland or forest) to sugarcane dramatically reduced soil carbon, creating a carbon deficit that would take decades to repay. While perennial grasses add carbon to the soil each year, DeLucia said, it could take up to a century for the sugar cane to rebuild soil carbon to former levels on native land.

Harvesting the corn residue for cellulosic ethanol production also reduced the carbon in the soil. The more plant residue was removed, the more the soil carbon declined.

Planting perennial grasses on existing agricultural lands had the most beneficial effect on soil carbon, the researchers found. Although there was an initial drop in carbon as fields were converted from corn to Miscanthus, switchgrass or native perennial grasses, the loss was fairly quickly offset by yearly gains in soil carbon as the grasses became established.

"Consistent with our hypothesis, the perennial feedstocks like Miscanthus and switchgrass start building soil carbon very, very early on," DeLucia said. "From a purely carbon perspective, our research indicates that putting perennial biofuel crops on landscapes that are dominated by annual row crops will have a positive effect on soil carbon."

The finding "seems to walk you right into the food for fuel debate," DeLucia said, referring to the controversy over using agricultural land for fuel production. But because the U.S. is already devoting about 20 percent of its corn crop to ethanol production, he said, it would make sense to eventually use that land to produce a much higher yielding biofuel feedstock that has the added benefit of increasing organic carbon in the soil.

These findings appear in December 2008 in the journal Global Change Biology Bioenergy.


Story Source:

The above story is based on materials provided by University of Illinois at Urbana-Champaign. Note: Materials may be edited for content and length.


Cite This Page:

University of Illinois at Urbana-Champaign. "Replacing Corn With Perennial Grasses Improves Carbon Footprint Of Biofuels." ScienceDaily. ScienceDaily, 5 December 2008. <www.sciencedaily.com/releases/2008/12/081202133228.htm>.
University of Illinois at Urbana-Champaign. (2008, December 5). Replacing Corn With Perennial Grasses Improves Carbon Footprint Of Biofuels. ScienceDaily. Retrieved December 19, 2014 from www.sciencedaily.com/releases/2008/12/081202133228.htm
University of Illinois at Urbana-Champaign. "Replacing Corn With Perennial Grasses Improves Carbon Footprint Of Biofuels." ScienceDaily. www.sciencedaily.com/releases/2008/12/081202133228.htm (accessed December 19, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Friday, December 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Kids Die While Under Protective Services

Kids Die While Under Protective Services

AP (Dec. 18, 2014) As part of a six-month investigation of child maltreatment deaths, the AP found that hundreds of deaths from horrific abuse and neglect could have been prevented. AP's Haven Daley reports. (Dec. 18) Video provided by AP
Powered by NewsLook.com
When You Lose Weight, This Is Where The Fat Goes

When You Lose Weight, This Is Where The Fat Goes

Newsy (Dec. 17, 2014) Can fat disappear into thin air? New research finds that during weight loss, over 80 percent of a person's fat molecules escape through the lungs. Video provided by Newsy
Powered by NewsLook.com
The Hottest Food Trends for 2015

The Hottest Food Trends for 2015

Buzz60 (Dec. 17, 2014) Urbanspoon predicts whicg food trends will dominate the culinary scene in 2015. Mara Montalbano (@maramontalbano) has the story. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins