Evaluating the sodium hazard in your irrigation water

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In the June 28, 2010 Super Journal report, "Evaluating the sodium hazard in your irrigation water" (188 KB pdf document), we present some new tools that will help you to get a more accurate estimate of the sodium hazard in your irrigation water. In order to help identify the most accurate estimate of sodium hazard, we have consulted several publications (including FAO Handbook 29, which is the standard guideline that most researchers and practitioners rely upon) and academics (most notably Dr. Don Suarez of the USDA Salinity Laboratory in Riverside, CA), and based on this input we have generated a mathematical model and accompanying spreadsheet. The spreadsheet will allow you to rapidly compute the sodium hazard for your irrigation water, based on data from your water quality reports.

Project title: Tools for estimating sodium hazard based on irrigation water quality reports

Principal investigator: Larry Stowell, Ph.D., CPAg and Wendy Gelernter, Ph.D.

• PACE Turf Super Journal Report, Tools for estimating sodium hazard based on irrigation water quality reports (188 KB pdf document) posted 6/28/10
• Spreadsheet for calculating sodium hazard of irrigation water (18 KB Excel spreadsheet)

Irrigation Water Guidelines

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Use these Irrigation Water Guidelines to help you evaluate your irrigation water quality.

10 years of monitoring recycled water: what we have learned

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Starting in 1999, we had a great opportunity to initiate a long-term study on the effects of recycled water on turf health and management. Thanks to PACE Turf member Jeff Beardsley of Big Canyon Country Club, we were able to study changes in soil chemistry in 14 fairways that were irrigated with recycled water, and 4 fairways that were irrigated with domestic water. The results of this study will be covered in a poster presentation that we will make at the Crop Science Society of America meetings this coming week in Houston, TX. You can view and print the poster here, though it is a fairly large (528 KB) pdf document. Some of the key points from the study include:

• Significant increases in soil salinity, nitrogen and organic matter were the most important trends observed in areas irrigated with recycled water.
• To reverse these trends, these management practices were instituted:
1. Periodic leaching to limit soil salts to less than 6 dS/m
2. Switch to higher quality domestic water during the summer months to mitigate build-up of salts and nitrogen
3. Aerification and sand topdressing to dilute organic matter and to allow increased leaching without loss of soil integrity
4. Re-surfacing of fairways to remove excess organic matter
5. Decreased rates of nitrogen fertilizer to accommodate the high levels of N delivered in irrigation water
• Although the focus is frequently on the quality of the recycled water, it turns out that soil chemistry, soil physical characteristics and rainfall patterns were equally important in the successful use of recycled water on golf courses.
• A contract with the water provider should define water quality limits and delivery guarantees, and should cover the cost of management programs (cultivation, amendments, monitoring programs) adopted to prevent soil and plant damage from long-term use of recycled water.

Posted 10/19/08