<div class="htmlview paragraph">The commercial development of the center pivot irrigation machine has brought the technology of machine design into an area formerly dominated by hydraulics and hydrology. The major attributes of these systems--accommodations to sandy soils and rolling terrain, efficiency in application of water, automation and flexibility in operation--are countered by depletion of the aquifer on a long-term basis and high energy consumption. The key to continued short-term expansion of center pivot irrigation will be the cost of energy relative to the market value of crops raised under the system.</div>