Automated Lysimeter for Irrigation and Drainage Control

by Claude J. Phene, USDA-ARS, Fresno, United States,
G. J. Hoffman, USDA-ARS, Fresno, United States,
Terry A. Howell, USDA-ARS, Fresno, United States,
David A. Clark, USDA-ARS, Fresno, United States,
R. M. Mead, USDA-ARS, Fresno, United States,
R. S. Johnson, USDA-ARS, Fresno, United States,
L. E. Williams, USDA-ARS, Fresno, United States,



Document Type: Proceeding Paper

Part of: Lysimeters for Evapotranspiration and Environmental Measurements

Abstract: Knowledge of crop evapotranspiration (ETc), the combined process of evaporation and plant transpiration, is important in agriculture for scheduling farm operations and designing and managing irrigation and drainage systems. Weighing lysimeters were used to measure ETc in a real-time feedback mode to schedule irrigations for the lysimeter and several irrigation systems in surrounding experimental fields of peaches and grapes. Results of testing indicate that the method can be used to (1) determine hourly ETc with an accuracy of ± 0.025 mm, (2) establish basic crop coefficient functions, (3) schedule irrigations in surrounding fields irrigated under similar conditions as the lysimeter, and (4) maintain the soil matric potential nearly constant within the root zone. With tree and vine crops, differences in growth and productivity between plants in the field and those in the lysimeter can occur because small growth differences are cumulative, whereas field crops are replanted annually.

Subject Headings: Measuring instruments | Irrigation systems | Crops | Evapotranspiration | Scheduling | Drainage systems | Control systems

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