Submitted to: Agricultural Research International Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: November 3, 1996
Publication Date: N/A
Technical Abstract: Lysimeters are routinely used to develop crop coefficients for crops grown in well drained soils. This paper describes the construction and operation of a pair of lysimeters being used to develop crop coefficients for irrigation scheduling of crops grown in the presence of shallow ground water. The soil tanks were constructed with an undisturbed top (1.7 m) and disurbed bottom layer (1.3 m) in order to maintain the integrity of the salinity profile in the top 1.7 m of soil. A Marriotte bottle is used to maintain a constant water table in one lysimeter, and the second lysimeter is a well drained soil. Instrumentation is installed to monitor water use from shallow ground water, soil water content, and root development in addition to mass changes of the lysimeter. The crop is irrigated with a subsurface drip irrigation system. With the exception of the soil water and root observations, the data collection and control is fully automated. In initial studies with cotton the system responded with the drained lysimeter showing higher evapotranspiration values than when a water table was present.