Meet alfalfa — conservationists’ ‘feedstock of choice’
Posted on August 13th, 2007By Allison Winter
Greenwire: Does alfalfa — the nation’s most planted legume and its third most valuable crop — have a future in a growing U.S. effort to produce its own energy supply?Some Agriculture Department scientists think so.
“We see alfalfa as a crucial crop for the biomass feedstock portfolio,” said Michael Russelle, a USDA soil scientist.
There’s good reason to root for alfalfa to become a key ingredient in cellulosic ethanol, Russelle and other scientists say. It is plentiful — already planted on millions of acres for livestock feed — and it is good for the environment.
Ghassem Asrar, deputy administrator of USDA’s natural resources and sustainable agriculture research, said alfalfa stands out among other potential feedstocks, because it can be grown everywhere and can make “fantastic” improvements on soil quality.
“We really believe this is a feedstock of choice,” Asrar said.
Proponents of alfalfa describe it as a wonder crop. It is self-fertilizing — fixing nitrogen from the air — and adds carbon to the soil, creating its own carbon sink and enriching the soil. Its long roots prevent erosion and improve soil and water quality.
But alfalfa is one of many contenders for biofuel feedstocks. Scientists are investigating hundreds of plants and plant waste products, and including prairie grasses and waste from corn, wheat and wood production are getting considerably more attention than alfalfa.
The Energy Department delivered $385 million in biorefineries grants this year for six companies focused primarily on corn stover, wheat straw, wood waste and native grasses. Alfalfa was not on the list. A DOE spokeswoman said the department is focused more on grasses and wastes than on row crops.
But there is a growing group of alfalfa backers in the National Alfalfa and Forage Alliance, which gathered in Washington last week to discuss use of the crop for bioenergy. They want recognition in the new farm bill of alfalfa’s conservation benefits and its potential for fuel.
“We’re not here to say it will be the only biofuel, but it is a good candidate,” said Beth Nelson, the alliance president.
The group formed last year, partially in response to slumping alfalfa acreage. Farmers cut down on alfalfa this year by 2 million acres from the year before, for a total of 21 million acres.
“It’s time for alfalfa to wake up,” Nelson said.
‘All biomass is local’
If commercial cellulosic ethanol technology gets off the ground, experts say there will be plenty of room for a variety of regional feedstocks. There would be corn waste in the Midwest, wood waste in the Southeast and native grasses in the Great Plains.
“All biomass is local,” said Bruce Dale, a Michigan State University professor who was among the first scientists to identify alfalfa’s fuel potential.
Alfalfa is “local” just about everywhere in the United States. It is an adaptable perennial that was introduced to the United States about 150 years ago and is now grown on more than 21 million acres in nearly every state. It is biggest in California, the Plains states and the Midwest. There is less alfalfa grown in the Northeast.
Dale first published research on alfalfa’s fuel potential more than 20 years ago and is currently researching switchgrass and corn stover. He said alfalfa “makes sense” as a feedstock for fuels, because it has “a number of desirable properties,” including its environmental benefits, the fact that it does not have to be planted every year and the potential to continue to use its leaves for animal food.
“The key is making sure to recover the protein value in alfalfa in getting it to market, and making the fiber, the cellulosic part, available for ethanol,” Dale said.
But on an energy-per-acre basis, alfalfa cannot compete with corn. USDA researchers found you could get about 137 gallons of fuel per acre for alfalfa stems, compared with about 473 gallons for corn. If farmers could also throw in corn stalks for cellulosic ethanol, that would increase corn yields to more than 600 gallons per acre — more than four times as much as alfalfa.
Alfalfa’s competitive edge could be its leaves, which are more nutritious for cattle and much higher in protein than the feed mix that is marketed as a co-product of corn ethanol. But removing leaves on a large scale is no easy task, and there is no commercial equipment currently available to do the work.
Biofuels rotation
While it is unlikely farmers would convert corn fields to alfalfa, researchers hope the crop could be a part of the ethanol mix on a farm, to improve soil and water quality. Farmers currently rotate alfalfa with corn to help enrich the soil between corn plantings.
“With alfalfa, when I put the corn out there, I don’t need to use Roundup Ready,” Gene Sandanger, the director of the National Corn Growers Association and a farmer in Hills, Minn. Roundup Ready corn is engineered to work with pesticides.
Sandager said alfalfa provides a “refuge” for his farm and saves him money on fertilizers and insecticides. USDA researchers have found that when rotated with other crops, alfalfa increases species diversity and interrupts disease or pest cycles. In California, more than 180 species — 27 percent of migratory and terrestrial wildlife — rely on alfalfa for cover, feed and reproduction
The concern among some soil scientists is that as the demand for corn ethanol grows, farmers may be more tempted to plant their land in “continuous corn,” which is heavy on fertilizers and insecticides.
“Continuous corn scares me,” said Hans Jung, a USDA research scientist in Minnesota.
Jung said a rotation of corn and alfalfa on a farm could yield as much as 409 gallons per acre — two-thirds the ethanol of continuous corn and more than a corn and soybean mix.
The economics of energy production from alfalfa could also be improved with new plant genetics. Some USDA scientists in Minnesota have already bred alfalfa plants for much larger stalks, which could potentially provide 40 percent more fuel per acre.
“You can get ethanol yields in theory that at least compare to continuous corn, plus there are the environmental benefits and the protein in the leaves,” Jung said.