تأثير آب مغناطيسي و شوري آب بر گرفتگي قطره‌چكان‌ها در آبياري قطره‌اي

An Investigation of Emitters Clogging Under Magnetic Field and Water Quality

در آبیاری قطره‌ای گرفتگی قطره چكان ها خصوصاً زمانی كه آب‌های مورد استفاده كیفیت نامناسبی داشته باشند، یكی از موانع جدی است. در این پژوهش گرفتگی قطره‌چكان‌ها تحت تاثیر آب معمولی، مغناطیسی و اسیدی در سه سطح شوری آب آبیاری (غیرشور، 7 و 14 دسی‌زیمنس بر متر) بررسی شد. طرح آزمایشی شامل كرت‌های خرد شده در قالب طرح كاملاً تصادفی با سه تكرار بود. به‌طوركلی نتایج نشان داد كه دستگاه مغناطیس كننده آب كه در این پژوهش مورد ارزیابی قرار گرفت، در شرایطی كه آب شور نباشد، مزیت نسبی بالاتری نسبت به آب غیرمغناطیس ندارد. در شرایطی كه آب شور باشد، اختلاف بسیار جزئی و غیرمعنی‌دار بین تیمارهای آب مغناطیسی و غیرمغناطیسی با ارجحیت آب مغناطیسی مشاهده شد. در اكثر شاخص‌های مورد ارزیابی، تیمار اسیدی با دو تیمار آب مغناطیسی و غیرمغناطیسی اختلاف معنی‌داری نشان داد. گرفتگی قطره‌چكان‌ها با زمان و هم‌چنین افزایش میزان شوری آب آبیاری بیش‌تر شد به‌طوری‌كه بیش‌ترین اختلاف مشاهده شده در بین تیمارها، در آخرین آبیاری و شوری 14 دسی‌زیمنس بر متر اتفاق افتاد.

Introduction: Water scarcity is one of the major problems for crop production. Using drip irrigation as an effective method in the efficient use of water is expanding in arid and semi-arid regions. One of the problems in under pressure irrigation during use of saline, unconventional and waste is emitters clogging. There are several ways to prevent particle deposits in pipes and clogging of emitters. Generally, conventional methods are divided into two categories: physical and chemical methods. In physical method, suspended solids and inorganic materials are removed using particles sediment sand and disc filters. In the chemical method the pH drops by adding acid to water resulting in the dissolution of carbonate sediments. With chlorine handling, organisms (i.e. algae, fungi and bacteria) that are the main causes of biological clogging are destroyed. However, the application of these methods is not successful in all cases. It has been observed that the emitters have gradually become obstructed. Magnetic water is obtained by passing water through permanent magnets or through the electromagnets installed in or on a feed pipeline. When a fluid passes through the magnetized field, its structure and some physical characteristic such as density, salt solution capacity, and deposition ratio of solid particles will be changed. An experimental study showed that a relatively weak magnetic influence increases the viscosity of water and consequently causes stronger hydrogen bonds under the magnetic field.There exist very few documented research projects related to the magnetization of water technology and its application to agricultural issues in general and emitter clogging in drip irrigation method, in particular. This technology is already used in some countries, especially in the Persian Gulf states. This research was designed and implemented aimed at increasing knowledge about the application of magnetic technology and its effects on emitters clogging in the drip irrigation system. Materials and Methods: A field experiment was carried out in 2011 in Gorgan Agricultural Research Station to study emitter clogging in drip irrigation using magnetic, non-magnetic and acidic water under salinity condition. The geographical location of the farm was 36° 55′ N, 54° 25′ E and 13.3 m above mean sea level with annual rainfall 400-450 mm. The experiment was laid out with a split plot in a complete randomized block design with three replications. The treatments included three treatments of the management of emitters clogging including, magnetized water (M), non-magnetized water (N) and acidic water (A) plus using three water quality levels namely, well water (S1), saline waters 7 (S2) and 14 (S3) dS m-1. Two methods were simultaneously used to magnetize water. In the first method, an electromagnet was installed around the sub-main pipe before the flow of water to the laterals. The amount of power required to magnetize the irrigation water was 0.03 kW-h of electricity per m3 of water. In the second method, the permanent magnets (ceramic magnets) were installed around the sub-main pipe before the laterals. In the second method the power requirement was 0.3 Tesla. To assess the emitter clogging, discharge and its variations as a function of time, emission uniformity, uniformity coefficient, and coefficient of variation were estimated and analyzed. Results and Discussion: The results of variance analysis showed that the effect of different irrigation management in irrigation system (N, M and A treatments) and different levels of water quality on all parameters were significant. Statistical comparison showed that in all cases there were no significant differences between magnetized water and non-magnetized water treatments. However, acidic water was statistically different from the two types of water mentioned. Both magnetic and conventional indices were examined in this study. However, no significant difference was observed. But in all cases, using magnetic water is advantageous compared with using non-magnetized water. The overall results have shown that the use of magnetized water in this study, in the non-saline water condition, does not offer a relatively higher advantage compared to the use of non-magnetized water. Conclusion: For saline water, insignificant differences were observed between magnetic and non-magnetic water treatments, however magnetic water was slightly preferable. Most of the indicators that were assessed showed that acid water treatment was significantly different from magnetic and non-magnetic water treatments. Thus, acid water treatment is not preferable. Emitter clogging with increase of time and the salinity level of irrigation water increased; the greatest difference between the treatments occurred in S3 and the last irrigation treatments. Magnetic water up to salinity level of 7 dS m-1, had no effect on the flow rate and thus on the emitter clogging. However, when using saline irrigation water and also with the increase of time, emitter clogging in magnetic water treatment was lower compared with non-magnetic treatment. Keywords: Emitters clogging, Magnetized water, Saline water