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Title: IRRIGATION OF FORAGE CROPS WITH SALINE DRAINAGE WATERS: VOLUMETRIC LYSIMETER STUDIES AND MODELING OF ROOT WATER UPTAKE AND DRAINAGE

Author
item Skaggs, Todd
item Poss, James
item Shouse, Peter

Submitted to: Proceedings of the International Salinity Forum
Publication Type: Proceedings
Publication Acceptance Date: 4/11/2005
Publication Date: 4/25/2005
Citation: Skaggs, T.H., Poss, J.A., Shouse, P.J. 2005. Irrigation of forage crops with saline drainage waters: Volumetric lysimeter studies and modeling of root water uptake and drainage. In: Proceedings of the International Salinity Forum, Managing Saline Soils and Water: Science, Technology, and Soil Issues. April 25-27, 2005. Riverside, CA pp:421-424.

Interpretive Summary: The disposal of agricultural drainage waters into surface waters or onto lands leads to salinization and degraded soil and water quality. In some instances the impacts of agricultural drainage disposal may be reduced if drainage waters are isolated and reused for irrigation. Scientific and economic questions remain about the suitability of different waters, soils, and crops for reuse operations; optimal management practices are not yet known. This paper reports results from recent studies in which forage crops were grown in volumetric lysimeters using synthetic saline-sodic drainage waters. The data are evaluated against a simulation model that could potentially assist in the design and management of agricultural drainage reuse systems. The results will be of interest to scientists, engineers, and growers working on the development of sustainable drainage management practices.

Technical Abstract: The disposal of agricultural drainage waters into surface waters or onto lands leads to salinization and degraded soil and water quality. In some instances the impacts of agricultural drainage disposal may be reduced if drainage waters are isolated and reused for irrigation. Scientific and economic questions remain about the suitability of different waters, soils, and crops for reuse operations, and about the effectiveness of various reuse management practices. Modeling is potentially a cost-effective approach of accelerating the development of optimal management practices, but data are lacking about the accuracy of simulated root water uptake under the dynamic, saline soil conditions encountered in drainage reuse operations. This work reports results from recent studies involving the production of forage crops (alfalfa and tall wheatgrass) in lysimeters using synthetic saline drainage waters. Root water uptake and drainage data were evaluated against an advanced numerical simulation (HYDRUS) that could potentially assist in the design and analysis of reuse management practices. We obtained good agreement between the model and the 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 (irrigation waters with electrical conductivities as high as 28 dS/m). 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.