Table 38

Table 38. Permissible Salinity Limits for Classes of Irrigation Water.

Concentration, total dissolved solids Concentration

Classes of Water Electrical conductivity umhos* Gravimetric ppm Sodium% Chlorides (Cl) Sulfates (SO₄)

Class 1, Excellent

250

175

20

4

4

Class 2, Good

250-750

175-525

20-40

4-7

4-7

Class 3, Permissible^1/

750-2000

525-1400

40-50

7-12

7-12

Class 4, Doubtful^2/

2000-3000

1400-2100

60-80

12-20

12-20

Class 5, Unsuitable^2/

3000+

2100+

80+

20+

20+

* Micromhos / cm at 25 degrees C
^1/ Leaching needed if used
^2/ Good drainage needed. Sensitive plants will have difficulty germinating and emerging

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	Concentration, total dissolved solids			Concentration
Classes of Water	Electrical conductivity umhos*	Gravimetric ppm	Sodium%	Chlorides (Cl)	Sulfates (SO₄)
Class 1, Excellent	250	175	20	4	4
Class 2, Good	250-750	175-525	20-40	4-7	4-7
Class 3, Permissible^1/	750-2000	525-1400	40-50	7-12	7-12
Class 4, Doubtful^2/	2000-3000	1400-2100	60-80	12-20	12-20
Class 5, Unsuitable^2/	3000+	2100+	80+	20+	20+