Table 1 Guideline of irrigation water quality31.

From: Seasonal groundwater quality analysis in a drought prone agricultural region using GIS and IWQI for nitrate contamination insights

Potential Irrigation Issues

None

Slightly to Moderately

Severely

Salinity

EC

(µS.cm−1)

< 700

700–3000

> 3000

TDS

(mg.L−1)

< 450

450–2000

> 2000

Infiltrations

SAR 0–3 and

EC=

> 700

700–200

< 200

SAR 3–6 and

EC=

> 1200

1200–300

< 300

SAR 6–12 and

EC=

> 1900

1900–500

< 500

SAR 12–20 and

EC=

> 2900

2900–1300

< 1300

SAR 20–40 and

EC=

> 5000

5000–2900

< 2900

Specific Ion Toxicities

Sodium (Na+)

SAR

< 3

3–9

> 9

Chloride (Cl−)

(mg.L−1)

< 140

140–350

> 350

Miscellaneous Impacts

Nitrate-nitrogen (NO3—–N)

(mg.L−1)

< 5

5–30

> 30

Bicarbonate (HCO3)

(mg.L−1)

< 91.5

91.5–518.5

> 518.5

pH

Normal range

6.5–8.5

  1. The Sodium Adsorption Ratio (SAR) serves as a critical indicator for assessing the potential soil structural degradation associated with irrigation practices. This parameter quantifies the relative proportions of sodium ions to calcium and magnesium ions in the water samples52,53,54. Elevated SAR values indicate sodium predominance, which can adversely affect soil physical properties, including structural stability, hydraulic conductivity, and infiltration capacity, ultimately impacting agricultural productivity45,46,47,55,56. The SAR values were calculated using the established Eq. (2) proposed by Wilcox53 (as cited in54):
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