Poor quality water

1. Poor quality water
1. Irrigation waters are not pure and may contain some
soluble salts.
2. In arid and semi-arid regions successful crop
production without supplemental irrigation is not
possible.
3. Irrigation water is usually drawn from surface or
ground water sources, which typically contain salts in
the range of 200 to 2000 ppm (= 200 to 2000 mg/Kg).
4. Irrigation water contains 10 – 100 times more salt
than rain water. Thus, each irrigation event adds salts
to the soil.

2. 5. Crop removes water from the soil to meet its
water needs (ETc) leaving behind most of the salts to
concentrate.
6. a salt balance in the soil has to be maintained
through proper water management practices for
continuous and successful cultivation of crops.

3. Sr. No. State
Saline soils
(ha)
Alkali soils
(ha)
Coastal saline soil
(ha)
Total
(ha)
1 Andhra Pradesh 0 196609 77598 274207
2 A & N islands 0 0 77000 77000
3 Bihar 47301 105852 0 153153
4 Gujarat 1218255 541430 462315 2222000
5 Haryana 49157 183399 0 232556
6 J & K* 0 17500 0 17500
7 Karnataka 1307 148136 586 150029
8 Kerala 0 0 20000 20000
9 Maharashtra 177093 422670 6996 606759
10 Madhya Pradesh 0 139720 0 139720
11 Orissa 0 0 147138 147138
12 Punjab 0 151717 0 151717
13 Rajasthan 195571 179371 0 374942
14 Tamil Nadu 0 354784 13231 368015
15 Uttar Pradesh 21989 1346971 0 1368960
16 West Bengal 0 0 441272 441272
Total 1710673 3788159 1246136 6744968
Extent and distribution of salt affected soils in India

5. Adverse effects of saline water
• salt accumulation,
• increase in osmotic potential,
• decreased water availability to plants,
• poor germination,
• patchy crop stand,
• stunted growth with smaller,
• thicker and dark green leaves,
• leaf necrosis & leaf drop,
• root death, wilting of plants,
• nutrient deficiency symptoms and poor crop yields.

7. Criteria to determine the quality
of irrigation water
• The criteria for judging the quality of irrigation water
are: Total salt concentration as measured by electrical
conductivity, relative proportion of sodium to other
cations as expressed by sodium adsorption ratio,
bicarbonate content, boron concentration and soluble
sodium percentage.

8. Total soluble salts
• Salinity of water refers to concentration of total soluble
salts in it. It is the most important single criterion of
irrigation water quality . The harmful effects increase
with increase in total salt concentration. The
concentration of soluble salts in water is indirectly
measured by its electrical conductivity (ECw).

9. Standards for classification of underground
water quality for irrigation
Characteristic
Fit
(safe)
Marg-
inal
Unfit
(unsafe)
Electrical conductivity
(EC) µmhos/cm
<2000
2000-
4000 >4000
Residual sodium
carbonate (RSC) me L-1 <2.5
2.5-
5.0
>5.0
Residual sodium carbonate (RSC) me L-1 = (CO -- + HCO3
-) – (Ca++ + Mg ++)
-where cations and anions are expressed in me L-1

10. Residual sodium carbonate (RSC) me L-1 = (CO -- + HCO3
-) – (Ca++ + Mg ++)
-where cations and anions are expressed in me L-1

11. Residual sodium carbonate (RSC)
• Bicarbonate is important primarly in its relation to Ca and
Mg. There is a tendency for Ca to react with bicarbonates
and precipitate as calcium carbonate. As Ca and Mg are
lost from water, the proportion of sodium is increased
leading to sodium hazard. This hazard is evaluated in terms
of Residual Sodium Carbonate (RSC) as given below:
Residual sodium carbonate = (CO3
-- + HCO3
-) – (Ca++ + Mg ++)
-where cations and anions are expressed in me L-1

12. Sodium Adsorption Ratio (SAR)
• SAR of water indicates the relative proportion of sodium
to other cations. It indicates sodium or alkali hazard.
• SAR= Na+/(Ca+++Mg++ /2 ) 1/2
•
• The ion concentration is expressed as meq per litre.
• Harmful effects of sodic water include destruction of soil
structure, crust formation, poor seedling emergence,
reduction in availability of N, Zn and Fe due to increased
soil pH, Na toxicity and toxicity of B & Mo due to their
excessive solubility.

13. Boron content
• Though boron is an essential micronutrient for
plant growth, its presence in excess in irrigation
water affects metabolic activities of the plant.
• Boron (ppm) Quality rating
• < 4 low
• 4-10 medium
• >10 high

14. Table 1: Soil pH of Punjab
Status
Soil pH Mean
No. of
polygons
Per cent
area of
state
Normal
6.5-8.7 7.99 487 94.76
Alkaline
8.8-9.3 8.91 30 5.04
Alkali
> 9.3 9.51 3 0.20

15. Water quality
• Residual sodium carbonate
(RSC) me L-1 = (CO3
- - + HCO3
-) – (Ca++ + Mg++)
• -where cations and anions are expressed in me L-1
The knowledge of quality of under ground irrigation
water is essential for planning their long-term optimum
utilization. Unlike unpolluted surface water, under
ground water is not always suitable for irrigation. Their
salt content and composition depend upon the location
and geo-climatic factors and thus, affect the water
quality for agriculture and for drinking purposes.

16. Table 10. Standards for classification
of under ground water for irrigation
Characteristic
Fit (safe)
Margi-
nal
Unfit (unsafe)
Electrical
conductivity (EC)
dS m-1
<2.0 2.0-4.0 >4.0
Residual sodium
carbonate (RSC)
me L-1
<2.5 2.5-5.0 >5.0

18. EC

19. Table 11. Electrical conductivity of
under ground water of Punjab
EC (dS m-1)
Mean (dS
m-1)
No. of
polygons
Area (ha)
Per cent
area of
state
<2.0 1.01 408 41,29,520 82
2.0-4.0 2.58 108 8,56,120 17
>4.0 4.72 4 54,617 1

20. CO3
--

21. Table 12 Carbonate in
under ground water of Punjab
Carbonate
(me L-1)
Mean
(me L-1)
No. of polygons Area (ha)
Per cent
area of
state
0.0-0.084 0.004 411 39,61,044 79
0.085-
0.500
0.18 42 4,09,657 8
0.501-
1.300
0.911 45 4,91,072 10
1.301-
4.000
1.827 22 1,74,232 3

22. HCO3
-

23. Table 13. Bicarbonate in
under ground water of Punjab
Bicarbonate
(me L-1)
Mean
(me L-1)
No. of
polygons
Area
(ha)
Per cent
area of state
0.08-4.60 3.53 112 10,14,829 20
4.61-6.93 5.87 172 19,99,339 40
6.94-10.40 7.99 224 19,52,665 39
10.41-
16.40
13.05 12 69,166 1

24. Cl-

25. Table 14. Chloride in
under ground water of Punjab
Chloride
(me L-1)
Mean
(me L-1)
No. of
polygons
Area
(ha)
Per cent
area of
state
0.2-2.0 0.929 335 34,64,768 68.8
2.1-4.5 3.114 52 5,74,104 11.4
4.6-10.0 7.27 105 7,95,688 15.8
10.1-66.1 15.052 28 2,01,440 4.0

26. Ca+++Mg++

27. Table 15. Calcium and magnesium
in under ground water of Punjab
Calcium and
magnesium
(me L-1)
Mean
(me L-1)
No. of
polygons
Area (ha)
Per cent
area of
state
0.36-3.70 2.834 132 12,76,416 25
3.71-5.68 4.67 226 23,46,202 47
5.69-8.60 6.71 116 10,01,793 20
8.61-38.00 11.22 46 4,11,589 8

29. Table 16. Residual sodium carbonate
in under ground water of Punjab
Range
(me L-1)
Mean
No. of
polygons
Area
(ha)
Per cent
area of
state
<2.5 0.892 297 27,92,571 55
2.5-5.0 3.365 179 18,81,354 37
>5.0 7.24 44 3,62,080 8

30. Acknowledge and Thanks
Author is immensely thankful to all the
websites and books whom I contacted to make
these slides more informative and attractive
By Dr. Kamini Roy

31. WE SHALL OVERCOME
Stay healthy
By Dr. Kamini Roy