Sodium absorption ratio (SAR)
The SAR value indicates the impact of sodium hazards combination with
calcium and magnesium ion for agricultural purposes. A high
concentration of sodium ions can reduce the physical properties of soil,
such as soil texture, size, voids, porosity, and permeability (Abbasnia
et al., 2019). In the study area, the SAR value range from 0.26 to 2.68,
with an average of 0.93 (Table.4). Richards (1954) classifications of
groundwater based on SAR are tabulated in table.5. All the sample
locations fall under the excellent class of water for irrigation uses.
The spatial distribution of the SAR value indicates 666.95sq.km area is
an excellent category (Fig.11a). It shows that groundwater’s present
nature is suitable for all types of soils and crops for irrigation.
Besides, the US Salinity classification (1954) of groundwater based on
the relationship between SAR versus EC is shown in Fig.13. About 80% of
the sample locations fall in C3-S1, 10% of the sample locations fall in
C2-S1, and 10% of the sample locations fall in the C4-S1 category. It
indicates that the majority of the sample locations are high salinity
with low sodium type of groundwater in the study area.