Lysimeters Versus Buffer Areas Et and Agronomic Comparisons

by Ivan A. Walter, W.W. Wheeler and Associates Inc, Englewood, United States,
Eugene G. Siemer, W.W. Wheeler and Associates Inc, Englewood, United States,
Larry R. Dirks, W.W. Wheeler and Associates Inc, Englewood, United States,
Joseph P. Quinlan, W.W. Wheeler and Associates Inc, Englewood, United States,
Robert D. Burman, W.W. Wheeler and Associates Inc, Englewood, United States,



Document Type: Proceeding Paper

Part of: Lysimeters for Evapotranspiration and Environmental Measurements

Abstract: Evapotranspiration (Et) from lysimeters may not represent Et of undisturbed, surrounding sites because of factors related to water, soils, plants, and even animal life. Et and agronomic responses in formerly irrigated mountain meadows were studied over a five year period in South Park, Colorado (elev. 2600 - 3050 m). Using deep (210 cm) in situ and shallow (45 cm) disturbed-soil lysimeters and neutron probes, research was conducted to determine Et under various water table levels in mountain meadows and to determine plant, soil and water responses. The paper reports on: (1) data pertinent to representativeness of lysimeters with respect to Et in mountain meadows, and (2) factors which affect the representativeness. Non-representativeness was also evidenced by the differences between the lysimeters and adjacent, undisturbed areas. Differences in Et, plant growth, total forage productivity, and species productivity were measured. Non-representativeness was evidenced by Et in lysimeters designed for measurement of potential Et differing from estimated values using a calibrated Et formula. The study found two primary causes of non-representativeness: (1) groundwater levels within the lysimeters differed from the buffer area, and (2) soil structure and plant roots were disturbed during installation.

Subject Headings: Measuring instruments | Soil water | Agriculture | Comparative studies | Water resources | Evapotranspiration | Groundwater | Mountains | Probe instruments | Irrigation | North America | Colorado | United States

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