Dormant Season Alfalfa Water Balance on the NIIP

Boman, Brian; ,

Dormant Season Alfalfa Water Balance on the NIIP

by Brian Boman,

Document Type: Proceeding Paper

Part of: North American Water and Environment Congress & Destructive Water

Abstract:

Non-growing season water balance parameters were measured for alfalfa under high-elevation desert conditions of the Navajo Indian Irrigation Project in northwest New Mexico. The lysimeters were in a loamy sand soil and constructed from plywood frames covered with plastic sheeting. The drainage lysimeters were 1.8 m in length, width, and depth and buried with the tops about 5 cm below the ground surface. Drainage water was removed by applying vacuum to ceramic candles or perforated drainage tubing in the lysimeter bottoms. Irrigation water was supplied by a sprinkler system as required. Alfalfa, with oats as a cover crop, was planted in the lysimeters in the summer of 1979. During the growing season, irrigation was applied to maintain well-watered conditions. In the dormant season, irrigation water was not applied and leachate from rainfall was periodically pumped from the lysimeters. Non-growing season water loss was calculated as precipitation?drainage?soil moisture change. The non-growing season was defined as the period from the first killing freeze in the fall to the beginning of spring growth in the next year (average temperature of 10C?). The lysimeter site recorded rainfall of 119 mm, 66 mm, 82 mm, and 144 mm for the 1979/80, 1990/81, 1981/82, and 1982/83 winter seasons, respectively. Non-growing season water loss for the 5 lysimeters averaged 114 mm, 146 mm, 147 mm, and 173 mm for the four seasons, with an average daily rate of 0.8 mm day^-1. Non-growing season water use amounted to 15% of the measured growing season FT.

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