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United States Department of Agriculture

Agricultural Research Service

Title: Water Use by Drip Irrigated Late Season Peaches

Authors
item Ayars, James
item Johnson, R -
item Phene, C -
item Trout, Thomas
item Clark, David
item Mead, R -

Submitted to: Microirrigation International Congress Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 30, 2000
Publication Date: N/A

Interpretive Summary: Irrigation water management can be improved by changing to more efficient irrigation systems, improving management of existing systems, and accurately meeting the water requirements of major crops. Proper irrigation scheduling requires actual crop water use data in relation to th potential water use (evapotranspiration) as a function of plant development. There is little information on the water requirements of deciduous fruit and nut crops as a function of growth. A large weighing lysimeter was constructed specifically to quantify the water requirements for an irrigated late season peach variety, and to develop a crop coefficient (Kc) to describe the crop water use as a function of time for a mature tree. The Kc was plotted against the day of the year and linear, quadratic, and cubic regressions were fit to the data. A three segment linear and the cubic equation had the best fit to the data. The maximum Kc determined for the linear fit in this experiment was 1.06 compared to a maximum of 0.92 recommended for use in California and 0.98 calculated using the method developed by the Food and Agricultural Organization of the United Nations. Average crop water use for the 4 years of the experiment was 1034 mm.

Technical Abstract: A four year experiment was conducted using a large weighing lysimeter to determine the crop coefficient and crop water use of a late season peach cultivar irrigated with a surface drip system. Two trees were planted in a 2 m by 4 m by 2 m deep weighing lysimeter that was surface irrigated with 2 L/hr in-line drip emitters. Irrigation was applied in 12- mm applications after a 12-mm water loss threshold was exceeded as measured by the lysimeter. The crop coefficient (Kc) was calculated using the measured water losses and grass reference evapotranspiration calculated using the CIMIS Penman equation. The Kc was plotted against the day of the year and linear, quadratic, and cubic regressions were fit to the data. A three segment linear and the cubic equation had the best fit to the data. The maximum Kc determined for the linear fit in this experiment was 1.06 compared to a maximum of 0.92 recommended for use in California and 0.98 calculated using the FAO method. Average water use for the 4 years of the experiment was 1034 mm.

Last Modified: 12/19/2014