Direct and Indirect Energy Use on Farms

Figure 1.5: Total Energy Directly and Indirectly Consumed on U.S. Farms in 2002 was 1.7 Quadrillion Btu.  Source: from Schnepf, 2004

Figure 1.5: Total Energy Directly and Indirectly Consumed on U.S. Farms in 2002 was 1.7 Quadrillion Btu. Source: from Schnepf, 2004

Direct energy use is that energy used in operation of farm equipment or machinery. Direct energy used in agriculture includes fuel for cropping and livestock operations: use of cars, trucks, tractors, and other machinery for field preparation, planting, and harvesting of crops; application of agricultural chemicals; transport of inputs and outputs to the farm and to market. Farm operations also use natural gas, liquid propane, and electricity for lighting, heating, cooling, and operation of equipment. Indirect farm energy use is that used for the manufacture of farm inputs such as fertilizers and agricultural chemicals [7] 1 .

In 2002, the agricultural sector used an estimated 1.7 quadrillion Btu of energy from both direct (1.1 quadrillion Btu) and indirect (0.6 quadrillion Btu) sources of an estimated 98 quadrillion Btu total energy used in the U.S. (Figure 1.5). Agriculture used 56 percent of the nitrogen used in the U.S. and 67 percent of the expenditures for pesticides in 2002 (7).

The steady decline in energy use from the late 1970’s to the 1990’s  can be attributed to energy-saving technologies and in-creased energy efficiency. The changes that precipitated this decline included: switching from gasoline-powered to diesel-powered engines, use of conservation tillage practices, use of larger, multifunction machinery, and new methods of crop drying and irrigation [1, 3].

In agriculture, there has been a long-term trend to reduce manual labor with technology, such as replacing manual scraping of manure with skid steer loaders and larger equipment  such as 24 row corn planter in-stead of a 4 row unit (Figure 1.7 ). While farm labor inputs fell almost 30 percent from 1996 to 2006, farm equipment use rose by ten percent. Increased use of farm equipment would indicate increased energy consumption. Nevertheless, energy inputs have not followed the same trend lines. Spikes in energy use in 2002 were followed by declines through 2006. These declines were precipitated by rising and volatile energy prices [2].

1 For a listing of direct and indirect farm energy uses, see table 1 in Schnepf, 2004.

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