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Evaluating your irrigation water

Interpreting the results from salinity-related tests of irrigation water

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Aspect Measured What It Could Affect Likelihood of a Salinity-Related Problem* Average Amounts in Recycled Water
None Slight to Moderate High Source 1** Source 2***
salinity expressed as ECw plant’s available water < 0.7 dS/m 0.7 – 3.0 dS/m > 3.0 dS/m 1.27 dS/m 1.25 dS/m
salinity expressed as TDS plant’s available water < 450 mg/l 450 – 2,000 mg/l > 2,000 mg/l 712 mg/l 729 mg/l
sodium via root absorption sensitive plants SAR < 3 SAR of 3–9 SAR > 9 SAR of 4.8 SAR of 3.9
sodium via foliar absorption sensitive plants < 3 meq/l > 3 meq/l --- 8 meq/l 6 meq/l
chloride via root absorption sensitive plants < 4 meq/l 4 – 10 meq/l >10 meq/l 4 meq/l 5 meq/l
chloride via foliar absorption sensitive plants < 3 meq/l >3 meq/l --- 4 meq/l 5 meq/l
boron sensitive plants < 0.7 mg/l 0.7–3.0 mg/l > 3.0 mg/l 0.9 mg/l 0.5 mg/l

* Adapted from Table 1 in Water Quality for Agriculture, FAO Irrigation and Drainage Paper 29, Rev. 1, by R. S. Ayers and D. W. Westcott, edition of 1994 (reprint).

** Adapted from Table 2-8 in Municipal Wastewater: Treatment and Reclaimed Water Characteristics, by T. Asano, R. G. Smith, and G. Tchobanoglous; Chapter 2 IN Irrigation With Reclaimed Municipal Wastewater: A Guidance Manual, by G. S. Pettygrove and T. Asano (editors), 1985, Lewis Publishers, Inc. Numbers shown here are averages for recycled water after “advanced treatment” — secondary treatment plus chemical coagulation as needed and filtration through sand or carbon media — from four southern California and two northern California water treatment plants.

*** Adapted from Negotiating Reclaimed Water Contracts: Agronomic Considerations, by Larry J. Stowell and Wendy Gelernter, 2001, a four-page report published by PACE Turfgrass Research Institute and available at Except for TDS, numbers shown here are averages for recycled water used on six southern California golf courses (from Table 1 of the paper). For TDS, the numbers here are averages based on data from unspecified golf courses (from Table 2).

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