341-10 Partitioning Evapotranspiration Into Evaporation and Transpiration In a Corn Field.



Wednesday, October 19, 2011: 10:40 AM
Henry Gonzalez Convention Center, Room 007B, River Level

Xinhua Xiao, Agronomy Building, Room 2493, Iowa State University, Ames, IA, Thomas Sauer, USDA-ARS National Laboratory for Agriculture & the Environment, Ames, IA, Jeremy Singer, USDA-ARS National Laboratory for Agriculture and the Environment, Ames, IA, Robert Horton, Agronomy Department, Ames, IA, Joshua Heitman, Campus Box 7619, North Carolina State University, Raleigh, NC and Tusheng Ren, No 2 Yuan Ming Yuan Xi Lu, China Agricultural University, Beijing, , CHINA
Evapotranspiration (ET) is a main component of the hydrology cycle. It consists of soil water evaporation (E) and plant transpiration (T). Accurate partitioning of ET into E and T is challenging. We measured soil water E using heat pulse sensors and a micro-Bowen ratio system, T using stem flow gauges, and ET using an eddy covariance system in a corn (Zea mays L.) field. Potential ET was also calculated with the Priestley-Taylor equation. The dynamic soil water E estimates from heat pulse sensors agreed well with those from the micro-Bowen ratio system, and the differences of the daily soil water E estimates from heat pulse and micro-Bowen ratio methods were within 0.3 mm. ET estimates from the sum of measured heat pulse E and stem flow T, from eddy covariance measurements, and from Priestley-Taylor calculations had similar trends. During the measurement period, measured E+T and eddy covariance ET accounted for 84% and 61% of potential ET, respectively. E and T accounted for 8% and 92%, respectively, of the sum of the measured E+T. The heat pulse method and the micro-Bowen ratio method are promising ways to measure soil water E, and they are useful for partitioning ET into E and T in a cropped field.
See more from this Division: S01 Soil Physics
See more from this Session: Measurement and Modeling of near-Surface Soil Water and Energy Fluxes: I