This document provides information on salinity management of irrigation water. It discusses several methods for managing salinity problems, including drainage to control water tables, leaching salts below the root zone, developing crop tolerance, optimizing cultural practices like irrigation timing, and changing or blending water sources. Drainage systems are shown to effectively reduce soil salinity and improve crop yields over time. Leaching requirements and crop tolerance data help determine appropriate irrigation amounts. Certain cultural practices like land grading and post-sowing irrigation can also improve crop establishment under saline conditions. The objective is to maintain acceptable crop yields through various salinity control strategies.

1. TERM PAPER ON
SALINITY MANAGEMENT OF
IRRIGATION WATER
SOIL,WATER QUALITY AND POLLUTION
AWM 506 – 3(2+1)

2. Contents
 Introduction
 Management of salinity problems
 Drainage
 Salinity control by leaching
 Crop tolerance to salinity
 Cultural practices
 Changing methods of irrigation
 Land development for salinity control
 Changing or blending of water
 conclusion

3. Introduction
 Water is classified as "saline" when it becomes a risk for growth and yield of
crops.
 Saline water has a relatively high concentration of dissolved salts (cations and
anions). Salt is not just "salt" as we know it - sodium chloride (NaCl) - but can
be dissolved calcium (Ca2+), magnesium (Mg2+), sulfate (SO4
2-), bicarbonate
(HCO3
-), Boron (B), and other compounds.
 Salinity of water is referred to in terms of total dissolved solids (TDS)
 Salinity is actually approximated by measuring the electrical conductivity (EC)
of water, expressed in decisiemens per meter (dS/m) or less often in
millimhos per centimeter (mmhos/cm) (the two measurements are
numerically equivalent).

4. Hazard TDS (ppm or mg/L) dS/m or mmhos/cm
None <500 <0.75
Slight 500-1000 0.75-1.5
Moderate 1000-2000 1.5-3.00
Severe >2000 >3.0
Electrical conductivity of water: The electrical conductivity of
water estimates the total amount of solids dissolved in water - TDS, which
stands for Total Dissolved Solids. TDS is measured in ppm (parts per million)
or in mg/l.

5. Management of salinity problems
“The objective of salinity control is to maintain an acceptable crop yield”
 Drainage
 Salinity control by leaching
 Crop tolerance to salinity
 Cultural practices
 Changing methods of irrigation
 Land development for salinity control
 Changing or blending of water

6. Drainage
 Salinity problems encountered in irrigated agriculture
are very frequently associated with an uncontrolled
water table within one to two meters of the ground
surface.
 Shallow water table management : To minimize the
salinity hazards where there is a high water table, the
salts are usually leached down and waterlogging
problems alleviated by the installation of a sub-surface
drainage system.
Water table is continual source of salts
Removal of salts by installing sub surface drainage system
Source: Hasanuzzaman,2005

7. Fig 1: Layout plan of subsurface drainage systems at Sampla (Haryana)
Source: Datta et al,2002

8. particulars Reclamation and yield in different drain spacings (m)
25 50 75 undrained
Soil Ece (dSm-1)
0 years 52.2 59.4 49.5 55.2
14 years after 2.1 2.6 4.4 66.0
Wheat yield (t ha-1)
0 years 0.0 0.0 0.0 0.0
12 years
average
4.9 4.6 4.2 Not
cultivated
Table 2: Changes in soil salinity (0-15 cm) and crop yield at Sampla (Haryana)
Source: Datta et al,2002

9. Leaching
 The main method of reducing the effect of saline water is to
apply extra water to leach salts below the root zone.
 Leaching often occurs with rainfall. In other cases, irrigation
water beyond the crop's water requirement may need to be
applied.
 The extra irrigation water needed to leach salts is termed
the leaching fraction, and this can be calculated for various
crops and soil types. Fig 2: Leaching of salts
below the root zone
Fig 3: Leaching of salts by rainfall

10. How much water should be used for leaching..
1.Leaching requirement
 To estimate the leaching requirement, both the irrigation water salinity (ECw)
and the crop tolerance to soil salinity (ECe) must be known
 The water salinity(ECw) can be obtained from laboratory analysis while the Soil
salinity (ECe) should be estimated from appropriate crop tolerance data.
ECw
LR = ----------------------------
5 (ECe) – Ecw
Where :
LR = the minimum leaching requirement needed to control salts
within the tolerance (ECe) of the crop with ordinary surface methods
of irrigation.
ECw = Salinity of the applied irrigation water in dS/m
ECe=Average soil salinity tolerated by the crop as measured in soil
saturation extract.

11.  The total annual depth of water that needs to be applied to meet both the crop
demand and leaching requirement can be estimated from :
ET
AW = --------------
1 – LR
Where : AW = depth of applied water (mm/year)
ET = Total annual crop water demand (mm/year)
LR = Leaching requirement

12. FIELD CROPS 100% 90% 75% 50% 0%
ECe ECw ECe ECw ECe ECw ECe ECw ECe ECw
Barley (Hordeum vulgare) 8.0 5.3 10 6.7 13 8.7 18 12 28 19
Cotton (Gossypium
hirsutum)
7.7 5.1 9.6 6.4 13 8.4 17 12 27 18
Sugarbeet (Beta vulgaris) 7.0 4.7 8.7 5.8 11 7.5 15 10 24 16
Sorghum (Sorghum bicolor) 6.8 4.5 7.4 5.0 8.4 5.6 9.9 6.7 13 8.7
Wheat (Triticum aestivum) 6.0 4.0 7.4 4.9 9.5 6.3 13 8.7 20 13
Soybean (Glycine max) 5.0 3.3 5.5 3.7 6.3 4.2 7.5 5.0 10 6.7
Cowpea (Vigna unguiculata) 4.9 3.3 5.7 3.8 7.0 4.7 9.1 6.0 13 8.8
Groundnut (Arachis
hypogaea)
3.2 2.1 3.5 2.4 4.1 2.7 4.9 3.3 6.6 4.4
Rice (paddy) (Oriza sativa) 3.0 2.0 3.8 2.6 5.1 3.4 7.2 4.8 11 7.6
Sugarcane (Saccharum
officinarum)
1.7 1.1 3.4 2.3 5.9 4.0 10 6.8 19 12
Maize (Zea mays) 1.7 1.1 2.5 1.7 3.8 2.5 5.9 3.9 10 6.7
Flax (Linum usitatissimum) 1.7 1.1 2.5 1.7 3.8 2.5 5.9 3.9 10 6.7
Broadbean (Vicia faba) 1.5 1.1 2.6 1.8 4.2 2.0 6.8 4.5 12 8.0
Table 3: Crop tolerance to salinity:

13. VEGETABLE CROPS
100% 90% 75% 50% 0%
ECe ECw ECe ECw ECe ECw ECe ECw ECe ECw
Tomato (Lycopersicon
esculentum)
2.5 1.7 3.5 2.3 5.0 3.4 7.6 5.0 13 8.4
Cucumber (Cucumis
sativus)
2.5 1.7 3.3 2.2 4.4 2.9 6.3 4.2 10 6.8
Spinach (Spinacia
oleracea)
2.0 1.3 3.3 2.2 5.3 3.5 8.6 5.7 15 10
Cabbage (Brassica
oleracea capitata)
1.8 1.2 2.8 1.9 4.4 2.9 7.0 4.6 12 8.1
Potato (Solanum
tuberosum)
1.7 1.1 2.5 1.7 3.8 2.5 5.9 3.9 10 6.7
Onion (Allium cepa) 1.2 0.8 1.8 1.2 2.8 1.8 4.3 2.9 7.4 5.0
Carrot (Daucus carota) 1.0 0.7 1.7 1.1 2.8 1.9 4.6 3.0 8.1 5.4
Source: Ayers et al,1994

14. Development of tolerance data:
 These data indicate that plant growth rate decreases linearly as salinity
increases above a critical threshold salinity at which growth rate first begins
to decrease.
 The following equation (Maas and Hoffman 1977) expresses the straight line
salinity effect on yield.
Y = 100 – b (Ece – a)
where : Y = Relative crop yield (%)
Ece = Salinity of the soil saturation extract
a = salinity threshold value.
b = yield loss per unit increase in salinity

15. IW/CPE Grain yields at EC Iw (dS/m)
BAW 4 8 12
AGRA (Bajra)
1.0 43.3 42.7 40.7 36.2
1.25 44.0 46.1 44.5 39.3
1.5 46.6 46.6 45.8 40.4
Dharwad (Sorghum)
1.0 32.7 27.3 27.32 24.7
1.25 35.5 31.5 30.0 28.9
1.5 33.5 29.3 26.6 27.4
Jobner(Barley)
1.0 50.8 42.3 44.4 43.1
1.15 47.7 44.4 41.1 41.0
Depth of irrigation water(cm) was 5.0,6.25,7.5 respectively for IW/CPE of
1.0,1.25,1.5 denotes the cumulative pan evaporation at which irrigation was
applied (5cm).
BAW is best available/canal water
Table 4: Yields of bajra, sorghum and barley as affected by leaching
fractions at different salinities of irrigation waters
Source: Minhas,2003

16. High tolerant
EC (iw) 10 dS/m
Tolerant
(5-10 dS/m)
Semi-tolerant
(3-5 dS/m)
Sensitive
(1.5-3.0)
Cereals
Barley wheat rice maize
oat
millets
Pearl millet Finger millet
sorghum Minor millets
pulses
Cluster bean Black gram
Pigeon pea Bengal gram
Cow pea Green gram
lentil
Oil seeds
Indian mustard Niger
castor Groundnut
Linseed Sunflower
Safflower sesame
soybean
Table 5: Crop tolerance to saline water:

17. High tolerant
EC (iw) 10 dS/m
Tolerant
(5-10 dS/m)
Semi-tolerant
(3-5 dS/m)
Sensitive
(1.5-3.0)
vegetables
spinach bitter gourd
Amaranthus Brinjal
Cabbage
Lady finger
Onion
Tomato
Carrot
pea
Sugar crops
sugarbeet tapioca sugarcane
Source : Gupta et al,
(use of saline water in agriculture,2003)

18. Cultural practices
 Land smoothing and grading
 timings of irrigation
 Placement if seed
 Fertilization.
Land smoothing and grading :
 Salinity control is difficult if a field is not sufficiently graded to permit uniform water
distribution.
 Germination is often poor in high spots due to shortage of water and excessive salinity,
while in low areas, similar poor crop due to result from water logging and soil crusting.
 To achieve this the fields should be properly levelled and bunded, and surface soil
should be kept open and protected against the beating action of raindrops.
 This can be achieved by ploughing in periods between the rains and by adopting other
water conservation practices. As well as increasing the intake of rainwater, ploughing
also helps in controlling the unproductive losses of water from weeds and evaporation.
 This practice will also reduce the upward movement of salts between rainfall events
and increase salt removal by rain.

19. Timings of irrigation :
 Conventional seeding of most crops is done when optimum moisture conditions
for tillage and seedbed preparation are attained following pre-sowing
irrigation.
 The objectives of pre-sowing irrigation should include leaching out the salts in
the seeding zone by a heavy application of non-saline water wherever possible.
 Another technique which seems to help in the establishment of crops is to use
post-sowing irrigation to push the salts deeper into the soil and to maintain
better moisture conditions (Minhas et al., 1988).
 However, the timing of this irrigation should be such as to avoid any subsequent
crusting problem. In a field experiment, Indian mustard was seeded with saline
water being used for both pre- and post-sowing irrigation and the results were
compared with the potential best available water.

20. EC(iw)
Seeding method
SM1 SM2 SM3
Plant
stand
(no/m2)
Yield
(kg/ha)
Plant
stand
(no/m2)
Yield
(kg/ha)
Plant
stand
(no/m2)
Yield
(kg/ha)
3 10.4 1670 10.6 1600 10.0 1510
7 9.8 1740 10.7 1620 9.7 1570
11 2.4 590 9.3 1540 7.4 1380
16 1.4 190 6.3 1290 2. 750
Table 6: Effect saline water on crop stand and yield of Indian mustard
SM1 : seeding after conventional pre-sowing irrigation.
SM2 : dry seeding followed by post-sowing irrigation.
SM3 : ½ pre and ½ post sowing irrigation.
Source: Minhas(CSSRI), karnal

21. ECiw(Ds m-1) Seed
yield
Water extracted (cm) from layer (cm)
0-30 30-60 60-90 90-150 total
Mung bean
0.3 (throughout) 25.2 27.8 9.7 4.0 3.3 44.8
4.7 (throughout) 2.7 16.6 5.8 0.2 - 22.6
4.7 (Plnsw) 15.6 23.4 9.7 4.2 0.7 38.1
sorghum
0.3 (throughout) 97.0 18.4 7.7 2.6 2.3 31.0
4.7 (throughout) 6.0 17.0 5.1 2.0 0.5 22.6
4.7 (Plnsw) 85.0 19.1 6.9 6.9 2.0 31.7
Indian mustard
0.3 (throughout) 23.2 19.5 9.0 6.2 2.2 36.9
4.7 (throughout) 10.5 10.7 5.1 1.8 0.5 18.1
4.7 (Plnsw) 18.0 13.7 7.7 4.8 1.7 27.9
Plnswc = pre sowing irrigation with non-saline water
Table 7: Yields and water extraction patterns following the use of different salinity
waters
Source: sharma et al, 2005

22. --------------------------
--------------------------
--------------------------
--------------------------
--------------------------
--------------------------
--------------------------
--------------------------
--------------------------
----------------------
----------------------------
----------------------------
----------------------------
-------------------------
Single row bed
= salt accumulated zone
------------
------------
------------
= water level
= seed fail to germinate
Alternate row irrigation
Increasing the depth of irrigation
Placement of seed:

23. --------------------------
--------------------------
--------------------------
--------------------------
--------------------------
--------------------------
-----------------------------
-----------------------------
-----------------------------
-----------------------------
----------------------------
----------------------------
----------------------------
-------------------------
Double row bed
= salt accumulated zone
------------
------------
------------
= water level
= seed fail to germinate
Alternate row irrigation
Increasing the depth of irrigation

24. -----------------------
- ------------------
--------------------------
--------------------------
--------------------
-----------------------
------ ----------------
-----------------------
Single row bed
Double row bed
Salinity control in sloping bed

25. Figure shows growth of barley crop when planted on the side of the
ridges to avoid affect of salts.

26. Fertilization :
 Fertilizers, manures, and soil amendments include many soluble salts in high
concentrations.
 If placed too close to the germinating seedling or to the growing plant, the
fertilizer may cause or aggravate a salinity or toxicity problem.
 For example, an application of 50 kg per hectare of nitrogen (240 kg/ha of
ammonium sulphate) would cause no salinity problem if spread uniformly over
a one hectare area.
 However, if drilled with the seed at planting time, it would probably reduce
germination or growth of seedlings and might result in crop failure caused by
the high salinity of the fertilizer placed too close to the seed.

27. Changing method of irrigation:
 The method of irrigation directly affects both the efficiency of water use and
the way salts accumulate.
 Flood and sprinkler irrigation are designed to apply water evenly over the entire
irrigated area. This results in most of the salts accumulating in the lower root
zone.
 In furrow irrigation salts from irrigation
water accumulate rapidly in the top few
centimeters of soil.
 Saline water move from the furrows towards
the center of the bed, any salts present
move with water and tend to accumulate in
the upper center of the bed.
Fig 4: Salt accumulation zones
under furrow irrigation system
Source: Shabbir et al, 2013

28. • Sprinkler irrigation (SI)
uniformly distributes water.
• Sprinkler irrigation leaches
the salts evenly. The lateral
salt distribution is relatively
uniform.
• The salts build up is in
deeper layers
• Drip irrigation delivers water near
to plants roots through closely
spaced emitters.
• Salt accumulation is lowest being
under the immediate vicinity of
water source, highest being at
surface, and center of two emitters
and boundary of wetted soil
volume.
• In sub-surface irrigation,
the soil above water
source has no means of
water to leach salts.
• This causes salts to
accumulate at surface
due to capillary rise and
evaporation
Fig 5: Salt accumulation zones
under sprinkler irrigation system
Fig7: Salt accumulation zones
under sub-surface irrigation
system
Fig 6: Salt accumulation zones
under drip irrigation system

29. Treatment Water use
(cm)
Yield
(t ha-1)
Tubers
No m-2
Wt/tuber
(g)
EC: 3dSm-1
Drip ET100 36.6 33.74 48 98.0
Drip ET75 27.4 27.8 33 100.0
Furrow. ET100 36.6 26.4 34 62.5
EC:10dSm-1
Drip ET100 28.8 27.5 55 59.0
Drip ET75 21.4 21.1 40 53.0
Furrow. ET100 34.0 18.1 32 65.8
Table 8: Effect of furrow and drip methods of irrigation at different ET levels
and water salinity on the yield of potato
Application of water with 10 dSm-1 in drip irrigation gives the equal yield compared
with water applied through surface irrigation and it have EC 3dSm-1.
Source : Gupta et al,
(use of saline water in agriculture,2003)

30. Table 9: Water use efficiency under different methods of irrigations and quality
of water in radish crop
Methods of irrigation Good quality water
(EC 0.25 dSm-1)
Saline water
(EC 6.5 dSm-1)
Yield
(q/ha)
WUE
(q/ha-cm)
Yield
(q/ha)
WUE
(q/ha-cm)
Sub surface irrigation 268 30 236 26
Surface irrigation 175 19 257 18
Surface (35 mm CPE) 164 14 99 9
Surface (60 mm CPE) 139 12 67 6
Source : Gupta et al,
(Use of saline water in agriculture,2003)

31. Blending of water
 A Poor quality ground water is usually abandoned if a better quality supply
becomes available.
 Blending the poorer with the better quality supply, thus increasing the total
quantity of usable water available.
 Blending will not reduce the total salt load but may allow more crop area to be
planted because of the increase in volume caused by dilution.
Concentration of blending water can be determining by using following formula
𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛
𝑜𝑓 𝑤𝑎𝑡𝑒𝑟 (𝑎)
𝑥
𝑝𝑟𝑜𝑝𝑜𝑟𝑡𝑖𝑜𝑛 𝑜𝑓
𝑤𝑎𝑡𝑒𝑟 𝑢𝑠𝑒𝑑
+
𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛
𝑜𝑓 𝑤𝑎𝑡𝑒𝑟 (𝑏)
𝑥
𝑝𝑟𝑜𝑝𝑜𝑟𝑡𝑖𝑜𝑛 𝑜𝑓
𝑤𝑎𝑡𝑒𝑟 𝑢𝑠𝑒𝑑

32. Treatment Average yields (q ha-1)
Wheat (5 years) Pearl millet(4 years)
Saline water (SW) 30.0 22.6
¾ SW + ¼ CW 36.2 23.3
½ SW + ½ CW 38.7 25.3
Canal water (CW) 40.0 29.8
Table 10: Effect of dilution with good quality water on the yields of wheat and pearl
millet
Nath et al,1982
Treatment Green fodder yield (t ha-1) Relative yield(%)
CW-CW-CW (T1) 21.0 100
CW-DW-DW (T2) 20.2 96
DW-DW-DW (T3) 19.2 91
Table 11: Effect of alternate irrigation with good quality water and drained
water on the yields sorghum
CW = Canal Water (EC, = 0.7 dS m-1)
DW = Drainage Water (ECdw = 7.2-8.6 dS m-1)
Source: Central Soil Salinity Research Institute, Karnal
(India)

33. Treatment Mode of application Grain yield (t ha-1) Relative yield (%)
T1 CW-CW-CW-CW-CW 2.81 100
T2 CW-CW-DW-CW-CW 2.43 87
T3 CW-DW-CW-DW-CW 2.30 82
T4 DW-DW-CW-CW-CW 1.79 64
T5 DW-CW-DW-CW-DW 1.75 62
T6 DW-DW-DW-DW-DW 1.59 57
Table 12: Grain yield (t ha-1) of sunflower under different modes of
irrigation
CW = Canal Water (EC cw = 0.7 dS m-1)
DW = Drainage Water (EC dw = 7.2-8.6 dS m-1)
Source: Central Soil Salinity Research Institute, Karnal
(India)

34. Saline water
irrigations
Canal water
irrigations
Mean yield for two seasons (q ha-1)
Grain Straw
0 14 27.1 39.4
4 10 30.8 37.4
7 7 29.2 34.0
9 5 29.2 33.6
14 - 21.9 29.5
Table 13: Grain and straw yield of rice as affected by different cycles
of saline and canal water irrigation
Source : Gupta et al,
(use of saline water in agriculture,2003)

35. Saline water
irrigations
Canal water irrigations Mean pod yield (3
years) (q ha-1)
0 10 16.28
3 7 14.33
5 5 13.72
7 3 13.12
10 - 8.23
Table 14: The pod yield of groundnut affected by different cycles of
saline and canal water irrigations
Source : Gupta et al,
(use of saline water in agriculture,2003)

36. Conclusions
 Minimize the salinity hazards where there is a high water table, the salts are
usually leached down and waterlogging problems alleviated by the
installation of a sub-surface drainage system.
 Leaching of salts with good quality water is the best method to removal of
salts in root zone
 Based on the irrigation water salinity Salt tolerant crops should be selected.
Barley is the highly salt tolerant crop
 Suitable planting practices, bed shapes, and irrigation management can
greatly enhance salt control during the critical germination period.

37.  Sprinkler irrigation is the best method for uniform removal of salts from the
root zone and give higher water use efficiency.
 If water scarcity is there blending the poorer with the better quality supply,
thus increasing the total quantity of usable water available.
 Various proportions of blended water or alternate application of poor and
good quality water give the best results.