Table 8 Classification of irrigation water based on SAR values (College of Agricultural Sciences 2002; U.S. Salinity Laboratory Staff 1954)
Level | SAR | Quality | Class | Hazard | Use of water for irrigation |
|---|---|---|---|---|---|
S1 | 0–10 | Low sodium | Excellent | No harmful effects from sodium | In all types of soil |
S2 | 10–18 | Medium sodium | Good | Problems on fine texture soils sodium sensitive plants, especially under low leaching conditions, but could be used on sandy soils with good permeability | In coarse textural soils with high permeability and rich in organic matter |
S3 | 18–26 | High sodium | Fair | Harmful effects could be anticipated in most soils and amendments such as gypsum would be necessary to exchange sodium ions | Requires good drainage and chemical amendments |
S4 |  > 26 | Very high sodium | Poor | Generally unsatisfactory for irrigation | Very poor for irrigation, require low salinity water, good drainage and addition of gypsum |