Irrigation Water Quality Assessment for Water Resources Used in Irrigation of Agricultural Fields of Kütahya - Alayunt Village

Just because of insufficient precipitations in several regions throughout the cropping year, irrigation has become the essential component of production activities to get high quality and quantity yields. Efficient and productive use of water resources plays a great role in sustainable management of available water resources. Such issues are also quite significant for meeting the domestic water needs of increasing population (over 80 million today), water needs of developing industries and water demands of agricultural irrigations. Natural quality water supply for these uses will only be possible with proper soil and water management practices [1].

Salts in irrigation water increase osmatic pressure of soil solution and thus negatively influence plant water use. High osmatic pressure reduces plant water uptake and ultimately results in plant die out. Therefore, salinity is used as quality and classification criterion for irrigation waters [2].

Annual total precipitations in arid and semi-arid regions of the world are not sufficient in leaching soluble salts accumulated within the root zones due to evaporation and water table close to soil surface. Therefore, inland reclamation practices, current salinity problems should be well-identified and leaching-induced change in soil salinity should be well-estimated [3]. Soil salinity is among the most significant abiotic stress factors directly limiting plant production worldwide. Salt stress also directly designates plant diversity in agricultural fields. Plant response to salt stress is controlled by complex molecular mechanisms. Salt stress results in various physiological changes in plants and plants develop different tolerance mechanisms against salt stress. Such changes and differences may sometimes emerge as plant-specific mechanisms or be common in all plants. These complex mechanisms could either develop directly as a response to salt stressor be accompanied with the other mechanisms developed against the other abiotic stress factors like drought. Therefore, salt stress and plant tolerance mechanisms should be well-comprehended both at plant level and tolerance level and salt-tolerant plant cultivars should be developed accordingly [4].

Total salt concentration of irrigation waters is expressed as electrical conductivity (EC x 106) in μmhos/cm (1000μmhos/cm= 1mmhos/cm= 1dS/m). Reliable irrigation waters mostly have total salt concentrations of lower than 2250 μmhos/cm. In terms only of total salt concentrations, electrical conductivity of irrigation waters should be less than 750 μmhos/cm. However, irrigation water with electrical conductivity values of between 750-2250 μmhos/cm are also largely used on irrigated lands provided that proper drainage and operational conditions are provided. Incase of insufficient leaching practices under improper drainage conditions, such waters may result in salinity problems in agricultural fields [5]. Anlıatamer [6] conducted a study to assess soil salinity in irrigation district of Ankara Haymana Türkşerefli Dam and indicated that Babayakup Creek merging with sub-branch of Şerefli Stream within the study area had a high electrical conductivity level, thus precautions should betaken while using this water in irrigations. It was also indicated that the increase in salinity levels of some areas was mostly resulted from unconscious irrigation practices of the farmers and application of low-quality irrigation waters through surface irrigation methods.

In another study, effects of different quality irrigation waters on alfalfa were investigated and it was reported that saline waters recessed the growth, reduced the yield and quality of alfalfa. On the other hand, when the sufficient leaching was provided and excess salt was removed from the field, plant growth and development reached back to normal levels. It was concluded that for high yield in alfalfa farming, irrigation water salinity should be less than 1.5 dSm-1 [7]. Gürcan [8] assessed the quality of irrigation waters in irrigation district of Ankara Haymana Soğulca Village Irrigation Cooperative and indicated that majority of irrigation water samples was classified as C (highly saline) and these waters 3 should not be used infields with limited drainage facilities. Despite the use these saline waters in irrigations, salinity problems were not encountered in irrigated lands. However, it was also indicated that for potential salinity problems not to be encountered in the future, open or underground drainage systems should be constructed in these fields. Topçu and Taş [9] conducted a study on Çanakkale Biga Plain and assessed electrical conductivity (EC), pH, potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), carbonate (CO ), bicarbonate (HCO ), chlorine (Cl), sulphate (SO ), nitrate 3 3 4 (NO ) and boron (B) parameters of irrigation water samples taken from 20 different groundwater wells. Samples were 3 classified based on Water Pollution Control Regulation of Turkey. In terms of salinity, 11 of 20 samples were classified as the second-class and the rest was classified as the first-class. Apart from nitrate pollution, generally no problem was encountered in study area during the study period.

Demer and Hepdeniz [10] conducted a study on Isparta Plain and assessed the water quality parameters of samples taken from 21 groundwater wells and reported the quality class of some water samples as C S (highly saline – low alkaline) and 3 1 the quality class of the rest as C S (moderately saline – low alkaline). 2 1 It was indicated in another study conducted in Left-Bank of Menemen irrigation district that improper irrigation methods and low water use efficiencies resulted in rising groundwater levels. High water tables negatively influence agricultural productions, thus to prevent high groundwater levels, either proper drainage facilities should be constructed or already available ones should be rehabilitated and maintained [11].

Dorak and Çelik [12] conducted a study to determine the effects of domestic and industrial wastewater effluents on water quality of Nilüfer Creek by taking water samples from the effluents of 5 treatment plants discharging their effluents into Nilüfer Creek and from the streams receiving effluents of these treatments in 4 different periods between August 2013 – May 2014. It was indicated that wastewater quality parameters varied with the sampling periods and in terms of ECand SAR, water samples were classified as between C S-C S classes. Quality parameters of water samples taken before and after 2 1 4 4 discharge of treated effluents indicated that wastewater effluents negatively influenced pH, EC, ammonia, phosphorus, sulphate, boron and chlorine values of Nilüfer Creek.

Akaroğlu and Seferoğlu [13] conducted a study in Sultanhisar town of Aydın province and indicated that irrigation water quality classes varied between C S-C S , canal water quality influenced fruit quality and boron contents of the plants 2 1 3 1 irrigated with these waters were greater than the control plants.

Aregahegn and Zerihun [14] assessed the water quality of Awash River and tributaries through selecting 17 different sampling locations throughout the Awash River and taking water samples four times in a year. For general water quality and suitability for irrigation, pH, EC, SAR, RSC, Na +, K +, Ca++ + Mg++, CO 2−, HCO − and Cl− like several water quality 3 3 parameters were looked for. Research findings revealed that all quality parameters of the samples taken from Beseka Lake were greater than allowable limits, physicochemical characteristics of Awash River exhibited changes based on different sampling sites and water quality parameters, pH and SAR values only of Beseka Lake and Meteka thermal water were greater than the allowable limits, ECvalues of Mojo, Wonji, Beseka, Melkasedi, Werer, Ambash, Meteka and Meteka thermal waters exhibited moderate-to-high salinity and these waters had quite a high RSC value. Treatment of industrial effluents was recommended to improve water quality.