more helpful for Agriculture students.

1. Presented by
Bhuneshwar Verma
M.Sc.(Ag.) Soil Science and Agricultural chemistry

2. •The concentration and composition of dissolved constituents in a
water determine its quality for irrigation use.
•Quality of water is an important consideration in any appraisal of
salinity or alkalinity conditions in an irrigated area.
•All irrigation waters contain some salts, but the concentration and
nature of salts vary.
•The quality of irrigation water depends primarily on the total amount
of salt present and the proportion of Na+ to other cations and certain
other parameters

3. •A number of parameters must be considered in dealing with recycled water
quality.
•Although the nutrient content of applied water has been listed as an advantage
of using recycled water, many of the nutrients may be salts that will influence
total soluble salts (TSS), TDS, or salinity.
•The most desirable situation is for recycled water to have as little residual
dissolved or suspended material as possible.

4. CRITERIA FOR EVALUATION OF IRRIGATION WATER
•Water quality is determined according to the purpose for which it will be used.
For irrigation waters, the usual criteria include salinity, sodicity and element toxicities.
Besides, many other criteria in assessing water quality for other uses namely, taste,
colour, odour, tubidity, temperature, hardness, pH, BOD or COD, nutrients content like
N,P etc.
Various criteria are considered in evaluating the quality of irrigation water namely:
•Salinity hazard or total concentration of soluble salts or Electrical Conductivity (EC).
•Sodium hazard or relative sodium concentration.
•Salt index.
•Bicarbonate hazard- Residual Sodium Carbonate(RSC).
•Boron concentration.
•Chloride concentration.
•Soluble sodium percentage(SSP).
•Magnesium hazard.
•Nitrate concentration.
•Lithium.

5. Water electrical
conductivity
(EC)(mmho/cm or
dS/m)
Water total dissolved
solids (TDS) (ppm)
Salinity hazard and effects on management
below 0.25 below 160 Very low hazard. No detrimental effects on plants,
and no soil build up expected.
0.25–0.75 160–480 Low hazard. Sensitive plants may show stress;
moderate leaching prevents salt accumulation in
soil.
0.75–2.0 480–1,280 Medium hazard. Salinity may adversely affect
plants. Requires selection of salt tolerant plants,
careful irrigation, good drainage, and leaching.
2.0–3.0 1,280–1,920 Medium-high hazard. Will require careful
management to raise most crops.
Above 3.0 Above 1,920 High hazard. Generally unacceptable for irrigation,
except for very salt-tolerant plants where there is
excellent drainage, frequent leaching, and
intensive management.
General hazard from salinity of irrigation water.

6. Various criteria for the evaluation of irrigation water with permissible limits for crop
growth are discussed:
1. Salinity hazard or total soluble salt concentration:
Water class EC (mSm-1 ) Salt concentration
(gl-1 )
Remarks
Low salinity 0-25 <0.16 Can be used safely
Medium salinity 25-75 0.16- 0.50 Can be used with
moderate leaching
High salinity 75-225 0.50- 1.50 Cannot be used for
irrigation purposes
Very high salinity 225-500 1.50- 30 Cannot be used for
irrigation purposes

7. 2. Sodium hazard:
Water class SAR value Remarks
S1 Low sodium hazard 0 – 10 Little or no hazard
S2 Medium sodium hazard 10 – 18 Appreciable hazard, but can be used
with appropriate management
S3 High sodium hazard 18 – 26 Unsatisfactory for most of the crops
S4 Very high sodium
hazard
> 26 Unsatisfactory for most of the crops
3. Bicarbonate hazard:
RSC Value (mel-1 ) Water quality
<1.25 Water can be used safely
1.25 Water can be used with certain
management
>2.25 Unsuitable for irrigation purposes

8. 4. Boron concentration:
Boron class Boron concentration (ppm) Remarks
Sensitive crops Semi tolerant
crops
Tolerant crops
Very low < 0.33 <0.67 < 1.0 Can be used safely
Low 0.33- 0.67 0.67-1.33 1.0 – 2.0 Can be used with management
Medium 0.67-1.00 1.33 – 2.0 2.0- 3.0 Unsuitable for irrigation
purposes
High 1.0-1.25 2.0 – 2.5 3.0 – 3.75
Very high > 1.25 > 2.5 > 3.75
Chloride concentration (mel-1 ) Water quality
4 Excellent water
4-7 Moderately good water
7-12 Slightly usable
12-20 Not suitable for irrigation
>20 Not suitable for irrigation
5. Chloride concentration:

9. Water constituent Intensity of problem
No problem Moderate Severe
Salinity (deci Siemens metre-1 )
Permeability (rate of infilteration affected)
salinity (dSm-1 )
Adjusted SAR, soils are
dominantly montmorillonite
dominantly illite-vermiculite
Dominantly kaolonite- sesquioxides
specific ion toxicity
sodium (as adjusted SAR)
Chloride (meq l-1 )
Boron (meq l-1 )
Miscellaneous
NO3
- - N or NH4
+ - N (meq l-1 )
HCO3
- (meq l-1 ) as damaged by
overhead sprinkler
pH
<0.75
>0.5
<6
<8
<16
<3
<4
<0.75
<5
<1.5
6.5 – 8.4
0.75-3.0
0.5-0.2
6-9
8-16
16-24
3-9
4-10
0.75-2.0
5-30
1.5-8.5
>3.0
<0.2
>9
>16
>24
>9
>10
>2.0
>30
>8.5
>9.5
Table: Guidelines for Irrigation water Quality established by the World Food and
Agriculture Organization (FAO)
Source: Modified from R.S.Ayres and D.W. Westcot, Water Quality for Agriculture, Irrigation and
Drainage Paper 29, FAO, Rome, 1976.

10. SOURCE: Modified from L.A. Richards(ed.), Diagnosis and Improvement of Saline and Alkali Soils, USDA
Agr. Handbook No. 60, 1954, p. 80.

14. Brackish water or briny water is water that has more salinity than fresh water,
but not as much as seawater.
it may result from mixing of seawater with fresh water, as in estuaries, or it
may occur in brackish fossil aquifers.
Certain human activities can produce brackish water, in particular civil
engineering projects such as dikes and the flooding of coastal marshland to
produce brackish water pools for fresh water prawn farming.
Technically, brackish water contains between 0.5 and 30 gms of salt per litre –
more often expressed as 0.5 to 30 parts per thousand, which is a specific gravity
of between 1.005 and 1.010.
brackish covers a range of salinity regimes and is not considered a precisely
defined condition.
It is characteristic of many brackish surface waters that their salinity can vary
considerably over space and/or time.

15. FRESH WATER BRACKISH WATER SALINE WATER BRINE
<0.05% 0.05 – 3% 3 – 5% >5%

16. a. Estuaries
b. Coast Line
c. Backwater
d. Mangroves
e. Lagoons

17. There are about 3.9 million ha of estuaries and 3.5 million ha of brackish
water areas available in the country.
It is estimated that about 1.2 million ha costal areas are considered brackish.
In addition to this, around 8.5 million ha salt affected areas are available in
the country.
The coastal mangrove areas is estimated around 0.5 million ha.

18. States Total brackish water area (ha)
Andhra pradesh 1,50,000
Goa 18,500
Gujarat 3,76,000
Karnataka 8,000
Kerala 65,000
Maharashtra 80,000
Orissa 31,600
Pondicherry 800
Tamil nadu 56,000
West bengal 4,05,000
Total 11,90,900

19. Salt balance is defined as the relation between the quantity of dissolved salts
carried to an area in the irrigation water and the quantity of dissolved salts
removed by the drainage water.
 Schofield in 1940 originated the term in the statement:
''If the mass of the salt input exceeds the mass of the salt output, the salt
balance is regarded as adverse, because this trend is in the direction of the
accumulation of salt in the area and such a trend is manifestly undesirable.''

20. This can be expressed algebraically as:
SB =Vdw Cdw – Viw Ciw
where SB indicates salt balance, which is expressed in kilo tons (k. tons) per year.
Vdw is the volume of drainage-water output and
Viw, is the volume of irrigation-water input, both in kilo acre-feet (k.a.f.) per year.
Cdw is the weighted mean concentration of dissolved solids in the drainage output,
and
Ciw, is the weighted mean concentration of dissolved solids in the irrigation input in
tons per acre-foot (t.a.f.).

21. Growing of salt tolerant crops and varieties is the best alternative.
Some of the salt tolerant crops are barley, sugar beet, mustard, cotton, turnips,
beetroot, date palm, coconut etc.
Some of the semi-tolerant crops are sorghum, pearl millet, finger millet, rice, castor
etc.
Application of farmyard manure or incorporation of green manure crops helps in
reducing the adverse effect of irrigation with poor quality water.
Application of fertilizers specially, nitrogen, phosphorus and zinc is essential.
Planting seeds on the side of the ridge helps in better germination than those planted
on the top of the ridge.

22. Selection of Crops
•For successful utilization of saline water, crops which are semi-tolerant to tolerant such as
mustards, wheat and cotton as well as those with low water requirement are recommended.
•Crops such as rice, sugarcane and Berseem, which require liberal water use, should be
avoided.
•In low rainfall areas (<40 cm/annum), mono–cropping is recommended for maintaining
salt balances.

23. Crop Saline environment Alkali environment
Wheat Raj 2325, Raj 2560, Raj 3077, WH 157 KRL 1-4, KRL19, Raj 3077,
HI1077, WH 157
Pearl millet MH269, 331, 427, HHB-60 MH 269, 280, 427, HHB 392
Mustard CS416,CS330,-1, Pusa Bold CS15, CS52, Varuna, DIRA 336,
CS 54
Cotton DHY 286, CPD 404, G 17060, GA HY6, Sarvottam, LRA
5166,JK276-10-5, GDH 9
Safflower HUS 305, A-1, Bhima Manjira, APRR3, A300
Sorghum SPV-475, 881, 678, 669, CSH 11 SPV 475, 1010, CSH 1, 11, 14
Barley Ratna, RL345, RD103, 137, K169 DL4, 106, 120, DHS 12

24. Cropping sequence:
• Cropping sequence is another critical step in mitigating saline conditions.
•The recommended cropping sequence for saline conditions are
•pearl millet –barley,
• pearl millet-wheat,
•pearl millet-mustard,
•sorghum-wheat or barley-sorghum-mustard,
•cluster bean – wheat or barley and cotton- wheat or barley.
• The pearl millet-wheat, pearl millet-barley, pearl millet-mustard, sorghum (fodder)-
wheat and sorghum (fodder)-mustard cropping sequences are more remunerative in
saline soils.
•Cotton based cropping sequence are not beneficial since the yield of the winter crops
that follow cotton are usually low.
•In areas with water scarcity, mustard could replace wheat in the cropping sequence since
its water requirement is low as compared to wheat.

25. Tree Species:
•In cases where it is neither feasible nor economical to use saline water for crop production,
such water can be used to raise tree species especially on lands those are already degraded.
•The preferred choice of species should be Azadirachta indica, Acacia nilotica, A. tortilis, A.
farnesiana, Cassia siamea, Eucalyptus tereteerms, Feronia limonia, Prosopis juliflora, P.
cineraria, Pithecellobium dulce, Salvadora persica, S. oleoides, Tamarix.
Medicinal Plants:
•Some medicinal plant such as Isabgol (Plantago ovata), Aloe and Kalmeg have also been
found promising under saline irrigation conditions as an alternative to arable crops

26. Often water of more than one quality is available at the same location.
One such situation commonly arises when farmers have access to limited supplies of
canal water along with saline ground water.
The existing fresh and saline water supplies could be suitably combined in several
ways.
First option is to blend the two supplies such that the salinity attained after mixing is
within the permissible limits of crop tolerance. The mixing of two water supplies from
canal and tubewell also helps in improving the stream size and thus enhances the
uniformity of irrigation especially in sandy soils.
 Application of the two waters separately, if available on demand, can be done either to
different fields, seasons or crop growth stages so that the higher salinity water is avoided
at sensitive growth stages of the crops.
 As the germination and seedling establishment stages have been identified as the
sensitive stages in most crops, better quality water should be utilized for pre-sowing
irrigation and early stages of crop growth. Then a switch over to poor quality water can be
made when the crops can tolerate higher salinity.