Design, Installation and Operation of a Twin Weighing Lysimeter for Fruit Trees

A large twin weighing lysimeter facility was installed at the Stephenville Agricultural Research and Extension Center, Stephenville, Texas, to measure evapotranspiration of mature peach trees. The system was designed to establish a check lysimeter so effects of irrigations or moisture stress or other treatment on the other lysimeter could be evaluated. Each lysimeter is a 2.44 m diameter cylinder 1.52 m deep. The weighing mechanisms for each lysimeter are three compression strain gage load cells with a sensitivity (hysteresis) of 4.54 kg. The load cell data from each lysimeter and on-site environmental data are automatically recorded on a micrologger with a sensitivity of 0.005 mv, which corresponds to a 4.45 kg weight. The equivalent depth of water for a sensitivity of 5 kg is 1 mm over the surface area of the lysimete.