Efficient water use in dryland cropping systems in the Great Plains

Successful dryland crop production in the semiarid Great Plains of North America must make efficient use of precipitation that is often limited and erratic in spatial and temporal distribution. The purpose of this paper is to review research on water use efficiency and precipitation use efficiency (PUE) as affected by cropping system and management in the Great Plains. Water use efficiency and PUE increase with residue management practices that increase precipitation storage efficiency, soil surface alterations that reduce runoff, cropping sequences that minimize fallow periods, and use of appropriate management practices for the selected crop. Precipitation use efficiency on a mass-produced basis is highest for systems producing forage (14.5 kg ha(-1) mm(-1)) and lowest for rotations with a high frequency of oilseed crops (4.2 kg ha(-1) mm(-1)) or continuous small-grain production in the southern plains (2.8 kg ha(-1) mm(-1)). Precipitation use efficiency when calculated on a price-received basis ranges from $1.20 ha(-1) mm(-1) (for an opportunity-cropped system with 4 of 5 yr in forage production in the southern plains) to $0.30 ha(-1) mm(-1) {for a wheat (Triticum aestivum L.)-grain sorghum [Sorghum bicolor (L.) Moench]-fallow system in the southern plains}. Throughout the Great Plains region, PUE decreases with more southern latitudes for rotations of similar makeup of cereals, pulses, oilseeds, and forages. Forage systems in the southern Great Plains appear to be highly efficient when PUE is computed on a price-received basis. In general across the Great Plains, increasing intensity of cropping increases PUE on both a massproduced basis and on a price-received basis.