Alfalfa Irrigation Termination, Maricopa

Abstract

Alfalfa irrigation is often withheld as a water conservation measure in Arizona. The objective of this research was to test the hypothesis that alfalfa can be permanently damaged by withholding irrigation water. Irrigation was terminated during the summer (July or August through September) or summer through winter (July or August through mid -March) on a Casa Grande sandy loam at Maricopa. Irrigation termination at Maricopa was not detrimental to stand although hay yields were depressed from 1.47 to 1.28 tons per acre following the second cycle of summer irrigation termination and from 1.57 to 1.23 tons per acre per cutting following summer through winter irrigation termination. Alfalfa water use was reduced by irrigation termination even after irrigation was resumed. Total nonstructural carbohydrates in the roots were never less than the control during irrigation termination but decreased relative to normally irrigated alfalfa when irrigation resumed.