Author
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Howell, Terry |
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Submitted to: Meeting Abstract
Publication Type: Abstract Only Publication Acceptance Date: 4/1/2002 Publication Date: 4/1/2002 Citation: N/A Interpretive Summary: Technical Abstract: New ideas are typically a wide open field. But new ideas for improving water use efficiency (WUE) have nearly been exhausted since the WUE term was first consistently defined and used in the early 1960s and more thoroughly described for differing scales (leaf, canopy, crop, or field) in the 1980s despite dramatic genotype advances in crops, irrigation system improvements, better understanding of irrigation water management, and agronomic enhancements. Often we are just applying known technologies that become cost effective as 1) interest rates decline, 2) energy prices for water pumping decline or stabilize; 3) greater value is placed on reducing labor cost, 3) operator convenience has greater value, or 4) water supplies or well yield declines dictate greater efficiency. Yet, we often observe large differences in the yield and evapotranspiration that define WUE within the field, among fields, farms and broader landscape definitions. The term irrigation water use efficiency (IWUE) has been considerably less consistently defined and applied compared with WUE. IWUE is the crop yield increase attributed to irrigation alone. WUE is usually defined as the economic yield (Y), expressed in g m**-2 or lbs ac**-1, per unit evapotranspiration (ET),expressed in mm or in., with the resulting WUE units of kg m**-3 or lbs ac-in.**-1. IWUE is defined as (Y-Yd)/IRR, where Yd is the dryland or non-irrigated yield (g**m-2 or lbs ac**-1) and IRR is the applied irrigation water (mm or in.). |
