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Farm to Save Energy, Curb Pollution
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Texas farmers integrate
old-world bluestem into cotton systems to save water and energy.
– Photo by Vivien Allen |
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A significant portion of the energy used in agriculture comes from
sources such as fertilizers, pesticides and other inputs that require
significant energy to produce. Reducing the use of these materials,
especially nitrogen fertilizer, is an effective way to cut back
energy use on the farm. For example, substituting manure for a ton
of nitrogen fertilizer saves 40,000 cubic feet of natural gas and
can reduce fertilizer costs by $85 per acre.
Farming practices such as grazing livestock, decreasing tillage,
cycling nutrients through manure and cover crops, and using rotations
to control pests also reduce energy use while improving soil organic
matter and decreasing soil erosion. Nutrient management plans, soil
testing, banding fertilizers and pesticides, and precision agriculture
similarly help reduce energy use.
Farm to Save Energy-Diversify Cropping Systems
In 1981, the Rodale Institute in Kutztown, Pa. launched what is
now the longest running field trial in the United States comparing
organic and conventional cropping systems. The conventional system
received fertilizers and pesticides following Penn State recommendations.
The other two systems were managed according to organic standards
using crop rotations, biological control and cover crops.
While all three systems produced similar yields of corn and soybeans
averaged over 20 years, the additional organic matter from manure
and cover crops enabled the two organic systems to do a far better
job of improving soil health, increasing water infiltration and
storing carbon. In the corn portion of the rotation, the organic
systems used only 63 percent as much energy as the conventional
system.
In northern Texas, drought and inefficient water use have forced
traditional cotton operations to pump water from the Ogallala Aquifer
at increasingly higher energy costs from ever-lowering water levels.
As of 2007, pumping water from 150 feet consumed $2.67 worth of
electricity per acre inch of water. Pumping from 300 feet, by comparison,
costs $4.84 per acre inch.
SARE-funded research at Texas Tech University led by scientist
Vivien Allen showed that farmers could successfully integrate pastures
into existing cotton monocultures to reduce demand for water and
energy. Instead of growing thirsty cotton continuously, farmers
have started putting some cotton land into pastures for grazing
livestock. Compared to continuous cotton, the integrated crop/livestock
system requires 23 percent less irrigation, 40 percent less purchased
nitrogen fertilizer and fewer pesticides.
In 2004, Allen was awarded a $6.2 million grant from the state
of Texas to continue the SARE-initiated work across 26 farmers’
fields. Early results confirm that the specific crop or variety
chosen can make large differences. Substituting a forage sorghum
for corn to make high quality silage, for example, uses about one-half
to one-third the irrigation water while netting similar yields and
higher returns.
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