ARS | Publication request: FORAGE CROP RESPONSE TO SALINITY AND WATER STRESSES: COMPARISON OF SIMULATED ROOT WATER UPTAKE AND DRAINAGE WITH LYSIMETER DATA

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 1, 2004
Publication Date: October 1, 2004
Citation: Skaggs, T.H., Poss, J.A., Shouse, P.J. 2004. Forage crop response to salinity and water stresses: comparison of simulated root water uptake and drainage with lysimeter data. Agronomy Abstracts. CD-ROM, Seattle, WA.

Technical Abstract: In numerical models of vadose zone water flow and solute transport, root water extraction is typically accounted for by introducing a sink term into the Richards equation. Various forms of the sink term have been proposed to simulate the reduction in water extraction that occurs when soil salinity and/or drought conditions exist in the root zone. While this representation of root water uptake is a fixture of modern simulation models, there has been relatively little work demonstrating agreement between the models and measured water uptake data, especially with respect to the salinity and water stress reduction functions. In this work, two forage crops (alfalfa and tall wheat grass) were grown over several months in large lysimeters using a range of salinity and drought treatments. Focusing on measurements of lysimeter drainage volumes and salinities, we obtained good agreement between the model (HYDRUS-1D) and data using a single set of salinity and water stress parameters for each crop, a noteworthy result given the broad range of experimental conditions considered. On the other hand, the required salinity and water stress parameters did not correspond to published salt tolerance data for these crops, suggesting that the near term prospects for using this model in a purely predictive capacity (i.e., without detailed crop- and site-specific calibration) are limited.