Agriculture Reference
In-Depth Information
bIoeneRgy: PotentIAl fRom AgRIcultuRe
And RuRAl AmeRIcA
Agriculture is primarily the business of producing crops and livestock. Crop pro-
duction is the growing of plants to capture solar energy in plant material for use as
food, feed, fiber, and other useful products. In the same way, forestry is primarily
the growing of woody plants for production of wood and fiber. Therefore, agriculture
and forestry are logical industries to produce biomass for energy.
Although biomass currently provides only 3% of the energy consumed in the
United States, it is the largest source of renewable domestic energy and the only
source of renewable liquid transportation fuel. Even though other renewable alterna-
tives are needed to completely address the earth's overall energy needs, replacing
liquid petroleum-based transportation fuel (gasoline and diesel) is probably the most
pressing need and one with few alternatives. The most likely source of renewable
liquid transportation fuel is biofuel.
No single bioenergy feedstock will provide all or even a major portion of energy
needs, and one geographical area will not be able to produce an adequate amount of
biomass. Rather, the overall bioenergy feedstock supply will consist of a combina-
tion of plant materials that can be efficiently produced economically, sustainably,
and in a viable quantity in each of the many agroecosystems that make up the range
of environments found in rural areas of the United States and the world. For energy
production to be sustainable, only biomass that is renewed on a recurring basis can
be used, and only that portion of the material not otherwise needed to sustain soil
productivity may be removed. That excludes removal of plant material needed on
the soil surface to control erosion and that needed to replenish nutrients and retain
soil organic matter. Organic matter, although in most cases representing 5% or less
of the soil volume, is critical in giving soil many of the attributes critical to success-
ful and sustained plant growth; aggregate stability, water and air exchange dynam-
ics, nutrient cycling, and energy for soil flora and fauna at the micro and macro
levels, to mention a few. Soil organic matter content (or the change in organic matter
content with change in management practice) is the current best single parameter
for assessing soil quality (Shukla et al., 2006). Soil quality must be enhanced to
improve productivity or at the minimum be maintained so that productivity is not
degraded. Similarly, other production inputs, including water, nutrients, crop pro-
tection materials, and energy, must be used sustainably. If the agricultural system
is not managed properly, neither energy nor food, feed, and fiber production will be
sustainable.
Given these constraints, how much feedstock or energy can agriculture and for-
estry sustainably provide? Are the land resources of the United States and of the
world adequate to produce the quantity of biomass needed to meet demands for food,
feed, and fiber and to provide energy?
U.S. ethanol production has been, and continues to be, almost totally from corn
grain. However, the quantities of corn and other grain available for use as an energy
feedstock will probably provide no more than 18 billion gallons of ethanol annu-
ally (NCGA, 2007). In fact, the U.S. Congress-approved Energy Independence and
Security Act of 2007 caps corn ethanol production at 15 billion gallons per year.
