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Title: Replicated lysimeter measurements of tracer transport in clayey soils: Effects of irrigation water salinity

Author
item Skaggs, Todd
item Suarez, Donald
item Goldberg, Sabine
item Shouse, Peter

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2012
Publication Date: 4/26/2012
Citation: Skaggs, T.H., Suarez, D.L., Goldberg, S.R., Shouse, P.J. 2012. Replicated lysimeter measurements of tracer transport in clayey soils: Effects of irrigation water salinity. Agricultural Water Management. 110:84-93.

Interpretive Summary: To maintain productivity in irrigated lands, it is necessary to periodically apply excess irrigation water so that accumulated, crop-damaging salts are leached below the root zone. Some recent studies suggest that existing guidelines for salinity management overestimate the amount of leaching that is required. Improved guidelines would save water, but data are needed to confirm new leaching calculations. In this research, we leached salts in large soil columns, and made intensive measurements of water flow and salt movement. The data will help researchers improve model calculations that will serve as the basis for new guidelines for leaching requirements.

Technical Abstract: Recent studies suggest that standard guidelines for managing salinity in irrigated agriculture overestimate the leaching requirement. Transient-state, process-based model analyses offer the possibility of more efficient water and salinity management, but data are needed to evaluate the accuracy of various subcomponents of the models. In this study, tracer (Br) transport in twelve lysimeters identically packed with clayey soil materials was monitored at eight soil depths and in drainage waters. In the first phase of the experiment (the salinization phase), six of the lysimeters were irrigated with high EC waters (8.1 dS m-1) and six with low EC waters (0.4 dS m-1). In the second phase, all lysimeters were leached with low EC waters (0.4 dS m-1). Tracer transport was very different in the high and low EC irrigation treatments, with the high EC treatment exhibiting significant tailing in the breakthrough curves. Due to the replicated experimental design, it was possible to confirm that the differences between the experimental treatments were significant and not due to random deviation. Future research aimed at placing realistic confidence levels on model predictions will allow transient-state models to reach their full potential as water and salinity management tools.