Evapotranspiration Measurement Using Eddy Covariance Systems for Irrigation Scheduling

Author(s): Sui, R.; Anapalli, S.; Baggard, J.; Murrell, C.

Irrigation plays a critical role in crop production. Irrigated crops produced more and stable yields than dryland crops. In the Mississippi Delta, acreage of irrigated land has increased rapidly in recent years. Uncertainty in the amount and timing of precipitation has become one of the most serious risks to crop production in this region. Crop producers have become increasingly reliant on irrigation to ensure adequate yields. Excessive withdrawal of the groundwater resulted in water level decline in the Mississippi River Valley Alluvial Aquifer. Ongoing depletion and stagnant recharging of the aquifer jeopardize the long-term availability of the aquifer and place irrigated agriculture in the region on an unsustainable path. Novel irrigation techniques and tools are needed for improving water use efficiency to maintain Mississippi water resource sustainability. Eddy covariance (EC) method is capable of measuring exchanges of water vapor between the surface of the earth and the atmosphere, and have been used for monitoring agroecosystems and measuring crop evapotranspiration (ET) for irrigation scheduling. Objectives of this project were to use EC systems to monitor the agroecosystem and measure evapotranspiration in Mississippi Delta for water management research and agroecosystem assessment. Five EC systems were set up in the Mississippi Delta for ET measurement and agroecosystem monitoring. Three of them are located in Stoneville, MS and two others in Arcola, MS. The EC system consisted of a CH4 analyzer for measuring methane gas flux, CO2/H2O analyzer for measuring carbon dioxide and water vapor fluxes, three-dimensional sonic anemometer for determining wind speed in three dimensions, and biomet (biological & meteorological) sensors to collect ancillary data for filling measurement gaps and interpreting flux results. Installation and preliminary field tests of the EC systems have been completed in 2016. These systems are being used to collect data in 2017 season. This presentation will report the ET measurement results with corn, soybean, and cotton in different locations in Mississippi Delta.

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