ASSESSMENT OF WATER QUALITY FOR IRRIGATION: A CASE STUDY IN PUNJAB

AMINA MUMTAZSenior Scientific Officer

PCSIR Laboratories Complex,Lahore

3

Agriculture

Industry

CommerceEC

ONOM

Y

Role of agriculture in economySAP –PK Blob ,2010

4

INTRODUCTION

• Soil salinity and sodicity problems are common in arid and semiarid regions because of insufficient rainfall.

• Nearly 10% of the total land surface is covered with different types of salt affected soils.

• 954 million hectors of saline soil is present on the earth’s surface. All these salt affected soils are distributed throughout the world.

5

Saline Soil Distribution on Earth

AFRICA8%

EUORP

E5%

AUSTRAILIA37%

AMERICA15%

ASIA34%

6

Cultivatable Area in Pakistan

17%

83%

Non-agri

Agri

7

DISTRIBUTION OF SALINE PATCHES IN PAKISTAN (million hectares)

Punjab

Sindh

KPK

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Series1

0.45

0.94

0.50

8

Salt affected land in Pakistan (million hectares)

Saline Permeable saline-sodic

Impermeable saline-sodic

Sodic0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

1.89 1.85

1.02

0.028

Series1

Industry & Economy, 2000,08

9

The major constraint faced by agriculture in Pakistan:

• Low availability and productivity of water• Primitive nature of farming• Water-logging and salinity• Problematic marketing system• Complex agriculture credit institutions• Inadequate research and extension services

AGRICULTURAL CONSTRAINS

10

• Under utilization of land resources• Achievable yield potential • Non-development of rain fed areas• Dwindling land area• Poor infra-structure• Pricing and quality of inputs• Wasteful irrigation system and methods and• Unchecked population growth

Contd…

Engineering News, 2010,43(10): 39

11

IRRIGATION WATER QUALITY CRITERIASoil scientists use the following categories to describe irrigation water effects on crop production and soil quality:

• Salinity hazards: total soluble salt content• Sodium hazards: relative proportion of sodium

to calcium and magnesium ions • pH: acidic or basic

12

• Alkalinity: carbonate and bicarbonate• Specific ions: Chloride, sulphate, nitrate etc. Other potential irrigation water contaminants that

affect suitability for agricultural use include• Heavy metals• Microbial contaminants

IRRIGATION WATER QUALITY CRITERIA, 2011,29: 0.506

13

Water Quality Guidelines• Water quality criteria- Not absolute • Water suitability– Soils–Management– Drainage

• A ten-fold range in the salt tolerance of plants gives wide scope for utilizing water of different quality.

• Referred guidelines areRichards (1954) Muhammad (1996)Ayers & Westcott (1976) Malik (1984)WAPDA (1981) WWF(2007)

Irrigation Water Quality Criteria

Parameters Status Richards,L.A.(1954)

WAPDA (1981)

Muhammad(1996)

Malik et al.(1984)

EC (Scm-1 ) Suitable 750 <1500 <1500 <1000

Marginal 751-2250 1500-3000 1500-2700 1000-1250

Unsuitable >2250 >3000 >2700 >1250

SAR Suitable <10 <10 <7.5 <6.0

Marginal 10-18 10-18 7.5-15 6.0-10.0

Unsuitable >18 >18 >15 >10.0

RSC (me L-1) Suitable <1.25 <2.5 <2 <1.25

Marginal 1.25-2.50 2.50-5.0 2-4 1.25-2.5

Unsuitable >2.5 >5.0 >4.0 >2.5

Cl (me L-1) Suitable <4.5 - 0-3.9 -

Marginal - - - -

Unsuitable >4.5 - >3.9 -

14

15

Conditions of water use and irrigation quality parameters by WWF

Conditions of Use EC(Scm-1 )

SAR RSC(me L-1)

Coarse Textured Soil 3000 10 2.5

Medium Textured Soil 2300 8 2.3

Fine Textured Soil 1500 8 1.25

Engineering News, 2010,43(10): 53

16

Effects of Poor Quality WaterBoth plant and soil problems can occur due to poor quality waters.

• Plant Factors• Soil Factors

17

Plant Factors Salinity• High soil salinity reduces the availability of soil

water to the plant and induces a drought condition i.e. osmotic effect

• The severity of the osmotic effect may vary with the plants growth stage and in some cases may go unnoticed because of a uniform yield decline over the whole crop

• Symptoms such as tip or marginal burn and defoliation may or may not occur

18

Toxicity• Specific ions from the irrigation water may

accumulate in the plant and reduce yields.• Concentration by evaporation of either water

droplets on foliage or of soil water may help induce specific ion toxicities.

• Specific ion toxicities are commonly associated with woody perennials, such as citrus, stone and other fruits and result mainly from high concentrations of Na+ and chloride (Cl-) ions or occasionally boron.

Contd…

19

Miscellaneous

• Constituents such as iron and carbonate can at high levels stain plants to cause mainly cosmetic problems

Contd…

20

Soil Factors Permeability• When low salinity water is used on soils with high

exchangeable sodium percentage (ESP) levels the soil disperses and becomes impermeable.

• As a result it is difficult to supply enough water to the plant.

• Related cultural problems include increased soil strength, crusting of seed beds, water logging and accompanying problems (disease, weeds, nutrition, etc.).

Agricultural Water Quality Criteria ,2004,30:3

WATER SUPPLY

QUALITY ASSESSMENT

ANALYSIS

QUANTITY ASSESSMENT

EC CHEMISTRY

OSMOTIC EFFECT TOXICITY

SARRSC

SUITABILITYSUITABILITY

Soil typePlant tolerance

Plant factor Soil factor

MANAGEMENT

21

22

Measuring the Quality of Irrigation Water

• Electrical Conductivity

• Ionic composition

23

Electrical Conductivity• Electrical conductivity (EC) is the most

convenient way of measuring water salinity.

• There is however no unique factor that can be applied and the factor will vary with composition and concentration. Generally, it is more convenient to use electrical conductivity as the measure of salt content.

24

Ionic Composition• Individual ions that make up the solute in water

are often determined to identify specific ion toxicities and to assess the effect that the water will have on soil physical condition.

• The latter effect is most often assessed by the

sodium adsorption ratio (SAR) and residual sodium carbonate (RSC) of the water.

25

• SAR is a measure of the tendency of the irrigation water to cause the replacement of calcium (Ca+2) ions attached to the soil clay minerals with sodium ions (Na+1). Sodium clays have poor structure and develop permeability problems.

• RSC is the measure of the excess of carbonates (C03

-2) and bicarbonates (HCO3-1) over

magnesium (Mg+2) and calcium (Ca+2).With high RSC there is a tendency for Ca+2 and Mg+2 to precipitate in the soil, thus increasing the proportion of Na and increasing the SAR of the soil solution.

Agricultural Water Quality Criteria ,2004,30:2

26

CASE STUDYSheikhupuraGujranwala

27

Irrigation Water Evaluation Water analysis and the guidelines are the tools

used in the initial assessment of the water.

Sheikhupura and Gujranwala (villages) were selected for study. Water samples (tubewells) were collected in clean amber coloured 1-2 L samples bottle that were previously rinsed out with distilled water. It is imported that the samples must represent the water sources and special care may be needed to ensure that.

28

Comparison of EC values of samples with standards

0 1 2 3 4 5 6 70

200

400

600

800

1000

1200

1400

1600

SampleRichardWAPDA

Villages of Sheikhupura

EC(S/cm)

Shei

khup

ura

29

0 1 2 3 4 5 6 7 80

2

4

6

8

10

12

SampleRichardWAPDA

Villages of Sheikhupura

SAR

Comparison of SAR values of samples with standards

Shei

khup

ura

30

0 1 2 3 4 5 6 7 80

1

2

3

4

5

6

7

8

WAPDARichardsamples

Villages of Sheikhupura

RSC(me L-1)

Comparison of RSC values of samples with standards

Shei

khup

ura

31

0 1 2 3 4 5 6 7 80

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Richardssamples

Villages of Sheikhpura

Chloride ion(me L-1)

Comparison of Chloride ions values of samples with standards

Shei

khup

ura

32

0 1 2 3 4 5 6 70

200

400

600

800

1000

1200

1400

1600

SampleRichardWAPDA

Villages of Gujranwala

EC(S/cm)

Comparison of EC values of samples with standards

GU

JRAN

WAL

A

33

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.50

2

4

6

8

10

12

SampleRichardWAPDA

Villages of Gujranwala

SAR

Comparison of SAR values of samples with standards

GU

JRAN

WAL

A

34

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.50

1

2

3

4

5

6

7

8

9

WAPDARichardsamples

Villages of Gujranwala

RSC(me L-1)

Comparison of RSC values of samples with standards

GU

JRAN

WAL

A

35

0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.50

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Richardssamples

Villages of Gujranwala

Chloride ion(me L-1)

Comparison of Chloride ion values of samples with standards

GU

JRAN

WAL

A

36

Sheikhupura

fit80%

unfit20%

fit72%

marginal fit15%

unfit13%

Comparative analysis of Water quality criteria between Sheikhupura and Gujranwala

37

SUGGESTIONS Drainage

The most important requirement for irrigated agriculture. It is essential that either an underground or an open surface drainage system must be implemented in the region.

Land preparation It is essential that fields under irrigation must be

leveled through land grading as it provides uniform water application which is important for leaching.

38

• Crop rotation When it is possible, crops of high salt

tolerance should also be included in the cropping system.

• Irrigation methods and management Border and basin methods should be

preferred in order to minimize Salinization risk when good quality water is not available.

• Leaching Saline soil may be improved by leaching salts

from the root zone.

THANK YOU

40

41

Proposed pH value by WWFVillages Sheikhupura Gujranwala Standard limits

1 7.3 7.3 6.5-8.4

2 7.2 7.5 6.5-8.4

3 7.5 7.3 6.5-8.4

4 7.85 7.9 6.5-8.4

5 7.3 7.95 6.5-8.4

6 7.9 6.5-8.4

7 7.9 6.5-8.4

42

Tube well Sheikhupura

Villages

pH EC (Scm-1 )

SAR RSC(me L-1)

Cl-

(me L-1)1 7.3 798 0.47 7.4 0.36

2 7.5 950 1.18 1.54 4.0

3 7.2 648 0.40 2.2 0.5

4 7.85 543 0.24 0.2 1.07

5 7.3 796 0.49 1.25 1.15

6 7.9 1266 0.88 1.4 3.94

7 7.9 601 0.64 0.08 2.17

43

Canal WaterVillages pH EC(Scm-1 ) SAR RSC(me L-1) Cl-1(me L-1)

1 7.8

2 7.7

3

4

5

6

7

44

Tube well Gujranwala

Villages pH EC (Scm-1 )

SAR RSC(me L-1)

Cl-

(me L-1)

A 7.3 790 0.28 0.54 0.47

B 7.5 1456 0.68 1.08 2.53

C 7.3 798 0.58 1.52 0.45

D 7.9 1139 2.93 8.02 3.46

E 7.9 954 0.33 0.2 1.46