Weighing Lysimeters for Evapotranspiration Research in a Humid Environment

Abstract

Three weighing lysimeters were developed for evapotranspiration research at the University of Florida, Institute of Food and Agricultural Sciences, Plant Science Research and Education Unit near Citra, Florida. The lysimeter design followed accepted procedures as well as aspects unique to the study site, including a foundation designed for a perched water table outside the lysimeters, fetch distance, deep drainage, and lightning protection. Each lysimeter has a planted surface area of 2.32 m 2 and a soil depth of 1.37 m. The soil in each lysimeter is reconstructed sandy soil originally from the experimental site. The lysimeter facility includes monitoring wells, an automatic pumping system, and additional lightning protection system for load cells and soil moisture sensors. The construction materials and installation cost (excluding labor) were $63,443 for the three lysimeters. Lysimeter on-site maintenance, operation, and performance are discussed. Four load cells with an accuracy of 0.02% (0.12 mm) are used to weigh the average 5.8 Mg lysimeter mass, including the steel lysimeter tank and soil. Initial data show that the three lysimeters provided a consistent hourly evapotranspiration (ET c ) measurement over a five-day period in the summer season, although many field activities and precipitation events occurred. An additional 30 days of daily bahiagrass ET c resulted in a 0.82 ratio between the ET c and Penman-Monteith reference evapotranspiration in November 2003.

Assessing the Accuracy of 50 Temperature-Based Models for Estimating Potential Evapotranspiration (PET) in a Mediterranean Mountainous Forest Environment

“…Thus, accurate estimates of ET are necessary for implementing water management strategies and promoting efficient use of water resources, especially in regions facing water shortage, like the Mediterranean basin. Unfortunately, direct measurements of ET through techniques like lysimeters [10,11], eddy covariance [12,13], and the Bowen ratio energy balance (BREB) system are difficult due to the expensive equipment required and the practical difficulties involved. Therefore, several empirical mathematical models have been developed worldwide under various environments to estimate ET using meteorological data.…”

Insights on agricultural nitrate leaching from soil block mesocosms

“…However, mesocosm designs differ in their soil disturbance. One method entails building large boxes and backfilling with soil (Jia et al, 2006(Jia et al, , 2014, enabling straightforward construction of large mesocosms, but with severe soil disturbance. Others devised ways to enclose and/or harvest intact blocks of soil, thus minimizing disturbance (Brown et al, 1974;Harrold & Dreibelbis, 1951;Logsdon et al, 2002;Ostrom et al, 1998;Schneider et al, 1988).…”

Site‐specific estimation of spatiotemporal crop evapotranspiration through field‐level sensing data

“…In this framework, the K cb is defined as the ratio between ET c and ET in the absence of water stress. ET c can be estimated or measured using different methods, for example, weighing lysimeters (Jia et al, 2006;Williams & Ayars, 2005) evaporation pan, soil water balance (SWB-PM) (Allen et al, 1998;Senay et al, 2011;Xu & Singh, 2005), atmometer (ET gages) (Chen & Robinson, 2009), Bowen Ratio Energy Balance System (Kabenge et al, 2013), and Eddy covariance (EC) (Schume et al, 2005;Scott, 2010;Wilson et al, 2001). Lysimeter measurements (Xu et al, 2013) or mathematical models, such as the PM equation and iterative methods (Widmoser, 2009), are considered the most accurate methods for ET c estimation.…”