QUALITY ASSESSMENT OF GROUND WATER FOR IRRIGATION IN DISTRICT JHANG Muhammad Shafiq and Muhammad Saleem*

Transcription

1 Quality assessment of ground water for irrigation 149 QUALITY ASSESSMENT OF GROUND WATER FOR IRRIGATION IN DISTRICT JHANG Muhammad Shafiq and Muhammad Saleem* ABSTRACT A study was conducted in the Directorate of Land Reclamation, Lower Chenab Canal Circle, Faisalabad, Pakistan to assess the suitability of ground water of 106 villages of district Jhang for irrigation. Water sampling, one sample from each village, was done four times i.e. pre-monsoon 2009, post-monsoon 2009, pre-monsoon 2010 and post-monsoon Chemical analysis was done for electrical conductivity (EC), sodium adsorption ratio (SAR) and residual sodium carbonate (RSC). According to results, 30 samples (28.3% of total samples) were found unfit while remaining 76 samples (71.7%) were observed as fit for irrigation purposes. Eighteen samples (16.98%) had electrical conductivity higher than permissible limit ( 1.50 ds/ m), 7 samples (6.6%) were found having high SAR (>10m mol/l) 0.05 and 19 samples (17.92%) had high RSC ( 2.5 me/l). It can be inferred from data that quality of available ground water in some of the villages is not suitable for sustainable crop production and soil health. Installation of private tubewells in the area under study must be site- specific, keeping in view the groundwater quality data. Also farmers of locality may be aware of the existing situation of groundwater for irrigation purpose. KEYWORDS: Ground water, irrigation quality; electric conductivity; sodium adsorption ratio; residual sodium carbonate; Jhang; Pakistan. INTRODUCTION Pakistan is basically an agricultural country but most of its agriculturally productive area falls in the arid and semi-arid climate. The rainfall varies considerably ranging from less than 10 mm per annum in some parts of the country to more than 500 mm in other parts (5). Most of the rainfall is received during July to September (monsoon). So, potential production cannot be achieved without ensured irrigation supplies. Determination of water quality through analysis is pre-requisite for its better utilization by crops as it is essential for the maintenance of turgidity, absorption of nutrients and metabolic processes of plants. (11). *Directorate of Land Reclamation, Lower Chenab Canal Circle, Faisalabad, Pakistan.

2 150 M. Shafiq and M. Saleem Due to change in climate and thereby extended drought, surface-water resources of Pakistan were reduced by about 70 percent in 2003, compared with normal years (8). Unfortunately, canal water is not sufficient to exploit the potential of soil and crop cultivars under intensive cropping system. The scarcity of good quality surface water is becoming more acute day by day. So one has to rely on irrigation through tubewells. Irrigation through tubewells has advantage over rainfall as it is under control with respect to time and amount of water application. A study (8) has shown that out of 560,000 tubewells in Indus Basin, about 70 percent are pumping sodic water which in turn is affecting the soil health and crop yields. According to Hussain et al. (7) two third of underground water of Punjab is unfit for irrigation and requires prior amendment or scientific management. Ayers and Westcot (4) have stated that water used for irrigation can vary greatly in quality depending upon type and quantity of dissolved salts. Salts are present in irrigation water in relatively small but significant amounts. These salts originate from dissolution of weathering of the rocks and soil, including dissolution of lime, gypsum and other slowly dissolved soil minerals. The suitability of water for irrigation is determined not only by the total amount of salts present but also by the kind of salts. Water quality or suitability for use is judged on the severity of problems that can be expected to develop during long-term use. The problems that result vary in both kind and degree and are modified by soil, climate and crop, as well as by the skill and knowledge of water user. The soil problems most commonly encountered and used as a basis to evaluate water quality relate to salinity, water infiltration rate, specific ion toxicity and a group of other miscellaneous problems. According to Shakir et al. (14), 64 water samples were collected from new tubewell bores from various locations of district Kasur to check the quality of underground water for irrigation purpose. In these samples electrical conductivity varied from 524 to 5700 µs/cm, sodium adsorption ratio from 0.49 to while residual sodium carbonate ranged from zero to me/ L. Out of 64 samples, 26 were found fit, 8 were marginally fit and 30 samples were found unfit for irrigation. Zahid et al. (16) tested 680 water samples, of which 33 percent were found fit, 19 percent marginally fit and rest of 48 percent were observed as unfit. Rizwan et al. (13) evaluated ground water quality (96 samples) for irrigation in Rawalpindi district. They noted that 71 percent samples were fit, 9 marginally fit and 20 percent were found unfit for irrigation.

3 Quality assessment of ground water for irrigation 151 For successful crops production on sustainable basis without deteriorating soils, quality of groundwater is of main concern. Present study was carried out to assess the ground water quality in Jhang district of Pakistan for its irrigation suitability. MATERIALS AND METHODS This study was conducted in the Directorate of Land Reclamation, Lower Chenab Canal Circle, Faisalabad, Pakistan during the year In all 106 villages of district Jhang were selected. Water samples from tubewells of each village were collected four times i.e. pre-monsoon 2009, post-monsoon 2009, pre-monsoon 2010 and post-monsoon 2010 in plastic bottles after 30 minutes of tubewell operation. Tubewell selection was made at random and depth of bores ranged from 80 to 100 feet. Analytical work was carried out at Soil and Water Testing Laboratory, Directorate of Land Reclamation Punjab, Lahore. These samples were analyzed for anions (CO 3--, HCO 3-,), cations (Na+, Ca++ + Mg++), ph and EC. Sodium adsorption ratio (SAR) and residual sodium carbonate (RSC) were calculated with following equations: SAR= Na {(Ca + Mg)/2} 1/2 RSC (me/l) = (CO HCO3 - ) (Ca ++ + Mg ++ ) Here the concentrations are expressed in milli equivalents per liter (me/l) (12). Water quality was assessed according to criteria given by Malik et al. (9) (Table 1), while others are for comparison purpose. The data were analyzed statistically for mean, standard deviation and percentage following the procedure described by Steel and Torrie (15). The parameters TSS, SAR and RSC were calculated from primary data (EC, Ca + Mg, CO 3, HCO 3 and Na). Table 1. Irrigation water quality criteria. Parameter EC (ds/m) SAR RSC(me/L) Status Richards WAPDA Muhammad Malik et al. (1954) (1981) (1996) (1984) Suitable <0.75 <1.5 <1.5 <1.5 Unsuitable >2.25 >3 >2.7 >1.5 Suitable <10 <10 <7.5 <10 Unsuitable >18 >18 >15 >10 Suitable <1.25 <2.5 <2.0 <2.5 Unsuitable >2.5 >5.0 >4.0 >2.5

4 152 M. Shafiq and M. Saleem Soil characteristics Healthy soil consists of roughly 40 percent mineral, 23 percent water, 23 percent air, 6 percent organic material and 8 percent living organisms. Soil texture is concerned with the relative proportions of mineral particles of various sizes in a given soil. These particles are grouped into three basic categories: sand, silt and clay. Sand particles are the largest ones in soil other than gravel or other rocks. Intermediate sized particles are called silt. The very smallest particles in soil are clay. Twenty soil samples were collected from the selected study area (Table 2) at the depth of 0-15cm. These samples were analyzed for EC, ph, organic matter (%), available phosphorus (mg/kg), available potassium (mg/kg), saturation percentage, soil texture and for gypsum requirement (tons/acre). RESULTS AND DISCUSSION Soil analysis (Table 2) showed that EC of soil saturation extract ranged from 1.43 ds/m of Ghanwan village to 5.44 ds/m in Chak No. 462 JB, soil ph Table 2. Soil characteristics of some selected sites Village/ Chak No. Depth (cm) EC ds/m Soil ph Organic matter (%) Available phosphorus (mg/kg) Available potassium (mg/kg) Saturation (%) Texture Gypsum required (tons/acre ) 29/JB Loam Nil 216/JB Clay Loam /JB Loam /JB, Loam /JB Clay Loam /JB Loam Nil 255/JB Loam Nil Moza Thattha Loam Nil Basti Sadiqabad Loam Nil 270/JB Loam Nil 268/JB Loam Nil 450/JB Silt Loam /JB Loam /JB Silty /JB Loam 2.2 Ghanwan Loam Nil Hasnana 31/ Silty Nil Vajlana, 81/ Loam Nil Kot Mirza Loam Nil Kot Hayder 8/ Loam Nil

5 Quality assessment of ground water for irrigation 153 was in alkaline range, organic matter mostly less than 1%. Available phosphorus varied from 1.05 mg/kg (Chak 447JB) to mg/kg (Kot Mirza) whereas, available potassium was maximum (190 mg/kg) in Moza Thattha and minimum (40 mg/kg) in Chak 450 JB. Water analysis Out of total 106 selected points, on an average 30 samples (28.3%) were unfit and remaining 76 samples (71.7%) were fit for irrigation. Most of the samples were unfit due to high RSC followed by EC. The results about different indicators are detailed below:- Electrical conductivity (EC) Electrical conductivity of water samples ranged from 0.38 to 4.90 ds/m with mean of 1.31 ds/m and standard deviation of On an average 88 samples (83%) out of 106 had EC <1.5 ds/m whereas, remaining 18 samples (17%) had EC 1.50 ds/ m (Table 3 and 5). Table 3. Range, mean and standard deviation of irrigation quality parameters of ground water (Distt. Jhang). Parameter Range Mean Standard deviation EC (ds/m) SAR RSC (me/l) ph Table 4. Conditions of water use and irrigation water quality parameters. Conditions of use EC (µs/cm) SAR RSC (me/l) Coarse textured soil (sandy soils) Medium textured soil (silty soils) Fine textured soil (clayey soils) Irrigation water quality guidelines for Pakistan, proposed by WWF (2). Table 5. Relative frequency distribution of tubewell waters for different irrigation quality characteristics (Distt. Jhang). Parameter Class interval Relative freq. distribution Status No. of samples Percent of total samples EC (ds/m) < Fit Unfit SAR (m mol/l) 1/2 < Fit Unfit RSC (me/l) < Fit

6 154 M. Shafiq and M. Saleem > Unfit Irrigation water contains a mixture of naturally occurring salts. The extent to which the salts accumulate in soil will depend upon irrigation water quality, irrigation management and the adequacy of drainage. Salinity control becomes more difficult as water quality becomes poorer. As water salinity increases greater care must be taken to leach salts out of the root zone before their accumulation reaches the concentration which might affect yield. Water for irrigation generally classified as saline or unsuitable, can be used successfully to grow crops without long-term hazardous consequences to crops or soils, with the use of improved farming and management practices (3). Sodium adsorption ratio (SAR) SAR represents the relative proportion of Na to Ca + Mg. SAR of water samples ranged from 0.75 to with mean of 5.64 and standard deviation of 0.23 (Table 3). Considering relative frequency distribution regarding SAR (Table 4), 99 samples (93.4%) were fit and remaining 7 samples (6.6%) were found unfit. Sodium adsorption is stimulated when Na proportion increases as compared to Ca + Mg resulting in soil dispersion (6). At high levels of sodium relative to divalent cations in soil solution, clay minerals in soils tend to swell and disperse and aggregates tend to slake, especially under conditions of low total salt concentration and high ph. As a result, permeability of the soil is reduced and surface becomes more crusted and compacted under such conditions. Soil s ability to transmit water is severely reduced by excessive sodicity (3). Salts added to soil (kg/ acre foot of irrigation water) Total soluble salts (mg/l) of water multiplied with the factor gives kg of salts added to soil per acre foot of irrigation water applied. Crop growth reduction because of dissolved substances in the soil is similar to drought stressed effects. An osmotic gradient on salt affected soils is formed and water uptake by plant roots is increasingly restricted as the concentration of soil salts increases. As salts build up in soil, more frequent irrigation is necessary to flush out salts from root zone. Crop species differ in their abilities to withstand salt stress. EC (ds/m) 640 = mg/l and 1 acre foot irrigation water = = cubic feet One cubic feet = 28.3 litres 1 acre foot = = litres Parts per million (ppm) = 1mg or 10-6 kg/l

7 Quality assessment of ground water for irrigation 155 So 1 acre foot irrigation = = kg salts Maximum salts i.e kg with acre foot irrigation water are being added in soils of Chak No. 385/JB. The data given in Table 6 show the amount of salts added to soil per acre foot of irrigation in 106 villages of Jhang district. Monsoon effect on EC, SAR and RSC The results (Fig.1) show that there is negligible effect of monsoon season on chemical composition of water samples during This is due to very mild showers of rainfall in study area. Cations and anions The data (Fig. 2) further show the magnitude of cations and anions. Unfit water samples had higher values of Ca+Mg, Na and CO 3 +HCO 3.Quality points denote the private tubewells selected for determining the quality of groundwater for irrigation purpose.

8 156 M. Shafiq and M. Saleem Residual sodium carbonate (RSC) The irrigation water containing excess of CO 3 and HCO 3 precipitates calcium and hence sodium is increased in soil solution. It leads to saturation of clay complex with sodium and consequently decrease infiltration rate. The RSC values of water samples ranged from 0.1 to 14.4 me/l with mean of 1.6 me/l and standard deviation of 0.22 (Table 3). Eighty seven samples (82 %) out of 106 were fit and 19 samples (18 %) were found unfit (Table 6). The fitness of water of different sites depends upon the average condition of soil texture, quantity of irrigation water applied, soil drainage, infiltration rate, etc. alongwith other variables like climate and tolerance of crop to salts. It was observed that most of water samples were unfit due to high RSC (Table 6). Farmers can use high RSC water for growing crops after gypsum amendment. Gypsum requirement can be calculated by following formula: Gypsum requirement(kg)=rsc(me/l) Discharge (cusec) Working hours 8.8 Water quality also depends upon texture of soil. Irrigation water unfit for fine textured soils might not be used in coarse textured soils (Table 4). for salt tolerant crops like wheat, sorghum, etc. as these crops have physiology for moderating the ill effects of salts. Table 6. Village wise suitability categorization of water samples for irrigation. S. No. Village/Chack No. Fit/ Unfit Unfit due to CO 3 + Ca 2 * Av. EC (ds/m) TSS (mg/l) Salts added (kg/acre) HCO2 (me/l) +Mg 2 * (Me/L) 1 Thatha Asian Kharl Fit Sawan Pura Fit Piray Dakot Fit Harsay 290/4. Fit Chak No. 12/JB 61/24 Fit

9 Quality assessment of ground water for irrigation Chak No. 13/JB 39/15 Fit Kolian Fit Kot Mirza Fit Kot Hayder 8/8 Fit Chak No. 126/JB 28/25. Fit Chak No. 125/JB Fit Talib 21/11 Fit Chak No. 468/JB Fit Chak No. 129/JB Unfit RSC Chak Mo. 127/JB 15/1 Fit Chak No. 131/JB 54/20 Fit Biar Wala Fit Kot Ahmad Yar Fit Kot Lal Fit Hussain Khan Fit Chak No. 139/JB 95/23 Fit Chak No. 137/JB Fit Chak No. 147/JB Fit Chak No. 148/JB Fit Chak No. 144/JB Fit Table contd 26 Muhammad Islam 25/7 Fit Kot Taja Fit Kotla Shahzada Fit Thatha Fateh Ali Fit Chak No. 156/JB 22/16 Fit Chak No. 151/Jb Fit Chak No. 185/JB, Fit _ Chak No. 236/JB, 10/15 Fit _ Chak No. 157/JB, 57/25 Fit _ Chak No. 158/JB. 25/1 Fit _ Taj Bairwala Fit _ Chak No. 466/JB, 33/6 Fit Chak No. 187/JB, 23/13 Unfit EC Chak No. 186/JB, 14/25 Fit _ Chak No. 208/JB, 40/25 Fit _ Chak No. 197/JB, 10/15 Fit _ Chak No. 203/JB, 39/14 Fit _ Chak No. 242/JB, 32/16 Fit _ Chak No. 230/JB, 20/3. Fit _ Chak No. 194/JB, 15/24 Fit _ Chak No. 193/JB, 20/2 Fit _ Suleman 115/4 Fit _ Chak No. 229/JB. 40/10 Fit _ Chak No. 246/JB, 82/5 Fit _ Chak No. 247/JB, 10/9 Fit _ Chak No. 248/JB, 36/16 Fit _ Chak No. 338/JB, 5/6. Unfit EC,SAR,RSC Chak No. 253/JB, 60/14 Fit _ Chak No. 250/JB, 112/5 Fit _ Chak No. 162/JB, 34/16 Fit _ Chak No. 258/JB, 1/25 Fit _ Chak No. 464/JB, 114/5 Fit _ Chak No. Daultana 5/25 Fit _ Chak No. 260/JB, 50/3 Fit _ Chak No. 166/JB, 40/10. Fit _ Chak No. 160/JB, 60/5 Fit _ Chak No. 178/JB, 7/1. Unfit RSC Chak No. 182/JB, 80/6. Unfit EC Chak No. 172/JB, 31/22 Fit Chak No. 173/JB, 32/14 Fit Mukhiana 30/15 Fit Behlool Shahbal 60/5. Fit Faridwala 50/5. Fit Chak No. 220/JB, 60/11 Unfit RSC Chak No. 216/JB, Unfit EC Chak No. 448/JB, Unfit RSC Chak No. 447/JB, 31/2 Unfit EC,SAR,RSC

10 158 M. Shafiq and M. Saleem 73 Chak No. 452/JB 52/5. Unfit EC,SAR,RSC Chak No. 466/JB, 30/22 Fit _ Chak No. 255/JB, 45/4 Fit _ Moza Thattha Mala,. Fit _ Basti Sadiqabad, 15/25. Fit _ Chak No. 270/JB, 12/5 Fit _ Chak No. 268/JB, 10/3. Fit _ Chak No. 450/JB, 5/24. Unfit RSC Chak No. 385/JB, 38/22 Unfit EC Chak No. 462/JB, 60/17 Unfit EC,SAR,RSC Chak No. 461/JB, 27/14. Unfit RSC Ghanwan, 40/22. Fit Hasnana. 31/3 Fit Vajlana, 81/20. Fit Lakbadar, 123/21. Fit Kurriana, 24/15. Unfit EC,RSC Rooranwali, 97/5. Unfit EC Chak No. 479/JB, Unfit RSC Jalal Pur Unfit EC Maduke, Fit Table contd 93 Kot Khaira, Unfit RSC Bgaggri, 67/16. Unfit EC Majji Sultan, 65/6. Unfit RSC Chak No. 481/JB, 63/11. Unfit EC,RSC,SAR Chak No. 486/JB, 4/21 Unfit EC,SAR Chak No. 484/JB, Unfit RSC Rustam Sarghana, Unfit EC Rustam Sarghana, Unfit RSC Qaim Bharwana, 25/4. Unfit EC Waryamwala, 80/9. Unfit RSC Chak No. 489/JB, 28/21 Unfit EC,RSC,SAR Chak No. 493/JB, 82/2 Fit Chak No. Kot Mirza Fit Kaluwala, 48/21. Unfit EC Categorization of unfit samples No. of samples Unfit due to 10 EC 12 RSC 1 EC+SAR 1 EC+RSC 6 EC+RSC+SAR Consequences of high ph water on soil properties High ph water causes degradation of soil structure and hence hinders soil aeration, availability of nutrients to plants, percolation thereby decreases per hectare yield of crops. CONCLUSION It was concluded that out of 106 samples, 30 samples (28.3%) were found unfit while remaining 76 samples (71.7%) were found to be fit for irrigation purposes. Eighteen samples (16.98%) showed electrical conductivity higher than permissible limit ( 1.50 ds/m), 7 samples (6.6%) had high SAR ( 10 (m mol/l) 0.5 and 19 samples (17.92%) had high RSC ( 2.5 me/l).

11 Quality assessment of ground water for irrigation 159 RECOMMENDATIONS High EC groundwater should be applied jointly with good quality canal water whereas, high RSC and SAR water should be applied with chemical treatment of gypsum stones or by judicious application of sulphuric acid. An integrated, holistic approach is needed to conserve water and prevent soil salinization and water logging while protecting the environment and ecology. First, source control through the implementation of more efficient irrigation systems and practices should be undertaken to minimize water application and reduce deep percolation. Secondly, conjunctive use of saline groundwater and surface water should also be undertaken to lower water table elevations, hence to reduce the drainage need and to conserve water as well. Efficiency of irrigation must be increased by adopting appropriate management strategies, systems and practices and through education and training. There is usually no single way to achieve salinity control in irrigated lands and associated waters. Different approaches and practices can be combined into satisfactory control systems. The appropriate combination depends upon economic, climatic and social as well as hydro-geologic situations. REFERENCES 1. Anon Atlas Soil salinity survey of irrigated areas of Indus basin 41 million acres. Survey and Research Organization. Planning Division, WAPDA, Lahore. 2. Anon National surface water classification criteria and irrigation water quality guidelines for Pakistan, WWF. Hudiara Drain Project Phase II funded by UNDP under GEF Small Grants Programme. 3. Anon The Use of Saline Waters for Crop Production. Irrigation and Drainage. Paper 48. FAO, Rome. 4. Ayers, R.S. and D.W. Westcot Water Quality for Agriculture. FAO Irrigation and Drainage. Paper 29, Rev. 1. FAO, Rome. 5. Bhutta, M.N., M.R. Chaudhary and C.A. Hafeez Water quality issues and status in Pakistan. Proc. Seminar on Strategies to Address the Present and Future Water Quality Issues. Pakistan Council of Research in Water Resources Islamabad. Publication No Emerson, W.W. and A.C. Bakker The comparative effect of exchangeable Ca, Mg and Na on some soil physical properties of red brown earth sub soils. Australian J. Soil Res. 11:

12 160 M. Shafiq and M. Saleem 7. Hussain, N.A., A. Khan, M.K. Tanveer, M. Ahmad and A. Sattar Suitability of Punjab under-ground waters. J. Agric. Res. 29(4): Kahlown, M.A., M.A. Tahir and M. Ashraf Water quality issues and status in Pakistan. Proc. Seminar on Strategies to Address the Present and Future Water Quality Issues. Pakistan Council of Research in Water Resources, Islamabad. Publication No Malik, D.M., M.A. Khan and T.A. Chaudhry Analysis Method for Soil, Plant, and Water. Soil Fertility Survey and Soil Testing Institute, Punjab, Lahore, Pakistan. 10. Muhammad, S Soil salinity sodicity and water logging. p In: Soil Science. Rashid, A. and K.S. Memon. (eds.). National Book Foundation, Islamabad, Pakistan. 11. Rehman, O., B. Ahmad and S. Afzal Sources and quality of irrigation water in district Attock. J. Agric. Res. 49(2): Richards, L.A Diagnosis and improvement of saline and alkali soils. USDA Agriculture Handbook No. 60, U.S. Government Printing Office, Washington, D.C., USA. 13. Rizwan, K., T. Mahmood, Z. Abbas, M. Dilshad and M.I. Lone Ground water quality for irrigation in Rawalpindi district. Pak. J Soil Sci. 22(1): Shakir, M.S., M. Ahmed and M.A. Khan Irrigational quality of under ground water in Kasur District. Asian J. P. Sci. 1: Steel, R.G.D and J.H. Torrie Principles and Procedures of Statistics. 2nd Ed., McGraw-Hill Book Company, New York. 16. Zahid, P., S.S.H. Kazmi and K.H. Gill Characterization of irrigation quality of ground water in Gujrat District. Pak. J. Soil Sci. 22(1):