Technological changes in energy use in US agricultural production.

Energy is equally important to land, water, and human resources in U.S. crop production. In addition to human energy, sunlight and fossil energy are the primary energy resources utilized in agricultural production. Because all technologies employed in agriculture require energy resources, the measure of energy flow in crop production provides a good indicator of the technological changes that have taken place in this sector. Energy values (kilocalories) for various resources and activities remain constant, and this is a major advantage in assessing technological change in agriculture, in contrast to economic values that are continually changing depending on the relative supply and demand of various resources and services. Another advantage of using energy as a measure of change in agricultural technology is that it can help assess the substitution of different forms of energy for various practices, as well as the substitution of land, water, and labor resources for energy.