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

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.

► We measured Br transport in clayey soils packed in large lysimeters.
► Irrigation water salinity strongly affected Br leaching.
► Replicated trials offered unique view of transport variability.
► Predictive, mechanistic modeling of transport in clayey soils remains challenging.