Study on Irrigation Water Quality in the Rift Valley Areas of Awash River Basin, Ethiopia

Table 9

Classification of irrigation water quality.

Parameter	Range	Classification	References
pH	<6.5	Acidic	[20, 21]
	6.5–8.4	Permissible
	>8.4	Alkaline
EC (dS/m)	<0.25	Low saline (totally safe)	[15, 19, 20, 24, 25]
	0.25–0.75	Moderately saline (safe)
	0.75–2.25	Medium-to-high salinity (leaching required)
	2.25–4	High salinity (unsafe)
	4–6	Very high salinity (unsafe)
	>6	Excessive salinity (severe)
SAR	<10	Low (excellent)	[15, 19, 24, 25]
	10–18	Medium (good)
	18–26	High (doubtful)
	>26	Very high (unsuitable)
HCO3^−	<1.5	Normal	[25]
	1.5–8.5	Slight to moderate
	>8.5	Severe
Cl^−	<2	None (generally safe for all plants)	[15, 20, 25]
	2–4	Slight to moderate (sensitive plants usually show slight to moderate injury)
	4–10	High (moderately tolerant plants usually show slight to substantial injury)
	>10	Very high (can cause severe problems)
RSC (meq/L)	<1.25	Safe	[15, 25]
	1.25–2.5	Marginal
	>2.5	Unsuitable