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Title: Water quality impacts on infiltration rates and using chemical transport models as management tools

Author
item Suarez, Donald

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/27/2007
Publication Date: 3/28/2007
Citation: Suarez, D.L. Water quality impacts on infiltration rates and using chemical transport models as management tools. 2007 Salinity/Drainage Conference. March 28, 2007. Available on-line. http://www.lib.berkeley.edu/WRCA/WRC/pdfs/SD07aSuarez.pdf

Interpretive Summary:

Technical Abstract: Use of low quality waters for irrigation requires improved tools for managing soil salinity, and increased knowledge of chemical effects on infiltration, plant ion uptake, and impact to ground and surface water. Impacts of irrigation water with SAR (sodium adsorption ratio) 2,4,6,8 and l0 on infiltration were examined in a sequential irrigation-rain system at EC (electrical conductivity) 1.0 dS/m and EC 2.0 dS/m for one year under cropped and uncropped soil conditions. Reductions in infiltration were statistically significant above SAR 4, with EC having a minor impact on infiltration, suggesting greater infiltration hazard with higher EC waters than suggested by present water quality criteria. Development of the new, user friendly Extract Chem model allows for calculation of the chemical composition of a soil water extract at different water contents, considering cation exchange, mineral dissolution/precipitation and B adsorption. Current simple correction methods are shown not to be satisfactory, especially for soils containing gypsum. The model is also useful for calibration of salinity sensing data collected from 4 electrode resistivity and electromagnetic instruments. Examples are also given of the use of the UNSATCHEM model for optimizing irrigation management for use of high B containing irrigation waters, including those previously considered unsuitable for crop production. A series of experiments were conducted with flood and sprinkler irrigation of Se containing drainage waters in vegetable crops. Despite high salinity and sulfate concentrations, Se uptake was greatly enhanced by foliar adsorption without significant yield loss in most instances. Sprinkler irrigation could serve as part of a strategy to reduce Se concentration or loading in drainage waters.