ASSESSMENT OF WATER QUALITY FOR IRRIGATION: A CASE STUDY IN PUNJAB AMINA MUMTAZ Senior Scientific Officer PCSIR Laboratories Complex, Lahore

3 Agriculture Industry Commerce ECONOMY Role of agriculture in economy SAP –PK Blob,2010

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. 4

Saline Soil Distribution on Earth 5

Cultivatable Area in Pakistan 6

DISTRIBUTION OF SALINE PATCHES IN PAKISTAN (million hectares) 7

Salt affected land in Pakistan (million hectares) 8 I ndustry & Economy, 2000,08

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 9 AGRICULTURAL CONSTRAINS

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 10 Contd… Engineering News, 2010,43(10): 39

IRRIGATION WATER QUALITY CRITERIA Soil 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 11

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 12 IRRIGATION WATER QUALITY CRITERIA, 2011,29: 0.506

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 are 13 Richards (1954)Muhammad (1996) Ayers & Westcott (1976)Malik (1984) WAPDA (1981)WWF(2007)

Irrigation Water Quality Criteria ParametersStatusRichards,L.A. (1954) WAPDA (1981) Muhammad (1996) Malik et al. (1984) EC (  Scm -1 ) Suitable750<1500 <1000 Marginal Unsuitable>2250>3000>2700>1250 SARSuitable<10 <7.5<6.0 Marginal Unsuitable>18 >15>10.0 RSC (me L -1 )Suitable<1.25<2.5<2<1.25 Marginal Unsuitable>2.5>5.0>4.0>2.5 Cl (me L -1 )Suitable< Marginal---- Unsuitable>4.5->

Conditions of water use and irrigation quality parameters by WWF Conditions of UseEC (  Scm -1 ) SARRSC (me L -1 ) Coarse Textured Soil Medium Textured Soil Fine Textured Soil Engineering News, 2010,43(10): 53

Effects of Poor Quality Water Both plant and soil problems can occur due to poor quality waters. Plant Factors Soil Factors 16

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 17

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. 18 Contd…

Miscellaneous Constituents such as iron and carbonate can at high levels stain plants to cause mainly cosmetic problems 19 Contd…

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.). 20 Agricultural Water Quality Criteria,2004,30:3

WATER SUPPLY QUALITY ASSESSMENT ANALYSIS QUANTITY ASSESSMENT EC CHEMISTRY OSMOTIC EFFECT TOXICITY SAR RSC SAR RSC SUITABILITY Soil type Plant tolerance Plant factor Soil factor MANAGEMENT 21

Measuring the Quality of Irrigation Water Electrical Conductivity Ionic composition 22

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. 23

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. 24

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 (C ) and bicarbonates (HCO 3 -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. 25 Agricultural Water Quality Criteria,2004,30:2

CASE STUDY 26 Sheikhupura Gujranwala

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. 27

Comparison of EC values of samples with standards 28 Sheikhupura

29 Comparison of SAR values of samples with standards Sheikhupura

30 Comparison of RSC values of samples with standards Sheikhupura

31 Comparison of Chloride ions values of samples with standards Sheikhupura

32 Comparison of EC values of samples with standards GUJRANWALA

33 Comparison of SAR values of samples with standards GUJRANWALA

34 Comparison of RSC values of samples with standards GUJRANWALA

35 Comparison of Chloride ion values of samples with standards GUJRANWALA

36 Comparative analysis of Water quality criteria between Sheikhupura and Gujranwala

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. 37

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. 38

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Proposed pH value by WWF VillagesSheikhupuraGujranwalaStandard limits

Tube well Sheikhupura Villa ges pHEC (  Scm -1 ) SARRSC (me L -1 ) Cl - (me L -1 )

Canal Water VillagespH EC(  Scm -1 ) SARRSC(me L -1 )Cl -1 (me L -1 )

Tube well Gujranwala 44 VillagespHEC (  Scm -1 ) SARRSC (me L -1 ) Cl - (me L -1 ) A B C D E