Deficit Irrigation of Alfalfa for Water‐Savings in the Great Plains and Intermountain West: A Review and Analysis of the Literature

Autor: R. Bradley Lindenmayer, Neil C. Hansen, Joe E. Brummer, James Pritchett
Rok vydání: 2011
Předmět:
Zdroj: Agronomy Journal. 103:45-50
ISSN: 1435-0645
0002-1962
DOI: 10.2134/agronj2010.0224
Popis: Diversions of water from irrigated agriculture are occurring in the western United States to address increasing municipal and industrial demands. Deficit irrigation of alfalfa (Medicago sativa L.) could be a source of water without complete dry-up of irrigated fields. Water saving potential from alfalfa is high because it is a high water-use crop produced on 12% of the irrigated land in the United States. The objectives of this paper are to review alfalfa plant-water relations in the Great Plains and Inter-mountain West, to understand potential water savings through deficit irrigation, and to indentify management practices that maximize water-use efficiency (WUE). Alfalfa biomass yield exhibits a linear relationship to evapotranspiration (ET) with the slope of a regionally aggregated water production function of 0.16 Mg ha -1 cm -1 . Relative ET declines 30% faster than relative biomass yield under deficit irrigation or dryland management. Because early season harvests have greater WUE, combining full irrigation in spring with no irrigation during less efficient water-use growth periods may be more effective in saving water than season-long deficit irrigation. Management practices that can influence WUE under deficit irrigation include stand age, growth stage at harvest, and alfalfa variety. A potential complication with controlled deficit irrigation of alfalfa is an uncertain contribution to ET from a water table. As alfalfa roots develop over time, a significant percentage of total ET can come from water tables shallower than 200 cm and the percentage increases as availability of water from precipitation or irrigation declines.
Databáze: OpenAIRE
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