Irrigation Practices for Reduced Water Application - Texas High Plains

Abstract

IRRIGATION inventories conducted in 1984 by the Soil Conservation Service indicated the Ogallala aquifer in the Texas High Plains supported 1.84 million ha (4.54 million acres) of irrigated crops in a 41-county area. County inventory estimates of water pumped for crops indicate that limited irrigation of drought tolerant crops was practiced on over one-half and perhaps two-thirds of the irrigated area. Water pumped for irrigation declined from an average of 9.12 km3 (7.39 million acre-ft) during the full development period represented by 1964, 1969, and 1974 inventory years to 6.37 km3 (5.16 million acre-ft) in 1984, and average per hectare application declined from 404 to 347 mm (15.9 to 13.7 in.). The factors associated with reduced water application are increased sprinkler irrigation, recent adoption of surge-flow application to graded furrows, increased use of conservation tillage, increased use of wide-spaced furrows, tractor wheel compaction of irrigated furrows on moderately permeable soils, reduced tailwater runoff in graded furrow systems, reduced use or elimination of large preplant irrigations, and some shifts in crops to those that are successfully managed with reduced water application. Reducing irrigation water application offers opportunity for more effective use of rainfall that averages 472 mm (18.6 in.) annually.