Arkansas - CSU Revised Lysimeter Project_Application

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Water Supply Reserve Account ? Grant Application Form Form Revised May 2007 _______________________________________ 2020 Sorghum or vegetable ET for sorghum or vegetable; Alfalfa ET from reference lysimeter; Kc for sorghum or vegetable; Daily weather data and calculated reference ET This is a tentative schedule and will obviously be modified based on the data collected and changes in cropping patterns in the Arkansas Valley. Ongoing consultation with the State Engineer and the Colorado Water Conservation Board will insure that studies conducted and data collected will meet the needs of the State of Colorado. 6. Water Availability and Sustainability This research project will provide accurate data on the consumptive use of water by crops growing in the lower Arkansas River basin. Data obtained will be obtained for the major types of crops grown in the valley. The results will be used by the State Engineer?s office and others to manage water resources in the Arkansas River. 7. Please provide a brief narrative of any related or relevant previous studies. The lysimeter design and construction was based on consultation with USDA-Agricultural Research Service and Texas A&M staff in Bushland, TX. The following literature review was conducted by Tom Ley (2004). Lysimeters for evapotranspiration (ET) research can be classified as weighing or non-weighing, as monolithic or reconstructed soil profiles, and as gravity or vacuum drainage (Howell et al., 1991). Non-weighing lysimeters, also commonly called volumetric lysimeters, are among the simplest, most common, and least expensive type of lysimeters (Aboukhaled et al., 1982). These lysimeters are characteristically single tanks placed in the soil to define a control volume. Non-weighing drainage lysimeters work on the principle of volume balance in which ET is the difference of measured irrigation and precipitation applied to the control volume less the measured drainage water. Non-weighing lysimeters can be set up to maintain a constant water table level in the soil tank. The contribution to ET from the water table is the volume of water made up periodically to maintain the constant water table level. Both types of lysimeters are limited by soil water movement time delays and changes in soil water storage. While daily estimates of ET can be made under these limitations, the determination of ET is often more accurate over longer periods of time from weekly to monthly intervals (Aboukhaled et al., 1982). Due to this limitation, non-weighing lysimeters are not considered suitable for reference ET equation verification and crop coefficient research. They may, however, be very suitable low cost alternatives for studying the effects of varying water salinity levels and high water table conditions on crop ET up and down the Arkansas River Valley. Weighing lysimeters characteristically are composed of two tanks, an inner soil tank (control volume) which can move freely within an outer containment tank. Weighing lysimeters work on the principle of weight change as a direct measurement of water added by irrigation and/or rainfall and water lost by drainage and/or ET from the control volume. With irrigation, rainfall, and drainage water all measured independently, crop ET can be computed from weight change measured on the lysimeter. With precision weighing instrumentation, crop ET over very short intervals (15-60 minutes) can be accurately measured. Weighing lysimeters can be classified by the type of weighing mechanism used: hydraulic, floating, mechanical, electronic, combination electronic- mechanical (Howell et al., 1991; Grebet, 1991; Aboukhaled et al., 1982). The soil mass in a lysimeter is either generally an undisturbed soil block (monolith) or is disturbed soil backfilled into the lysimeter using the soil excavated from the pit where the lysimeter is installed. Soil monoliths should be 14