تغییرات مقادیر نیتروژن و فسفر خاک زراعی تحت کشت جو در اثر آبیاری با فاضلاب تصفیه‌‌شده

استفاده مستقیم از فاضلاب شهری خام برای آبیاری زراعی می‌تواند عواقب زیان‌بار بسیاری را ایجاد کند. بنابراین، پساب تصفیه‌شده از طریق فناوری‌های مختلف برای استفاده دوباره به‌ویژه در مناطق کم‌آب مورد توجه قرار گرفته است. هدف این پژوهش مقایسه کاربرد پساب تصفیه‌شده فاضلاب شهری نسبت به آب چاه بر میزان نیترات و فسفات در خاک زراعی تحت کشت جو بود. بدین منظور یک قطعه زمین زراعی به مساحت 2000 متر‌مربع به دو قسمت مساوی 1000 متر‌مربعی تقسیم شد که برای یک فصل رشد، یک قطعه آن با آب چاه و قطعه دیگر با آب فاضلاب تصفیه‌شده آبیاری شد؛ ضمن آنکه کیفیت این دو منبع آبی نیز در آزمایشگاه تعیین شد. تعداد 28 نمونه خاک نیز از هر یک از دو قطعه زمین (در مجموع تعداد 56 نمونه) از لایه 20-0 سانتی‌متری تهیه شده و در آزمایشگاه مورد تجزیه و اندازه‌گیری قرار گرفت. روش درون‎یابی وزن‎دهی فاصله معکوس نیز به‌منظور تعیین توزیع مکانی ویژگی‌های خاک به‌کار رفت. نتایج نشان داد که میانگین غلظت فسفات، پتاسیم و سدیم اندازه‌گیری‌شده در پساب تصفیه‌شده بسیار بیش‌تر از آب چاه بود و کاربرد پساب تصفیه‌شده فاضلاب شهری به‌طور معنی‌داری بر غلظت آمونیوم، فسفات و نیترات و نیتروژن کل خاک موثر بود. همچنین استفاده از پساب تصفیه‌شده شهری برای آبیاری توانست عملکرد گیاه جو (hordeum vulgare) را نسبت به تیمار آب چاه بهبود بخشد. قابل توجه آن‌که مدیریت مناسب در بهره‌گیری از فاضلاب تصفیه‌شده و انتخاب گیاهانی که بتوانند آثار زیان‌بار استفاده از این منبع آبی را بر ویژگی‌های خاک و عملکرد محصول به حداقل برسانند، اهمیت زیادی دارد.

changes in nitrogen and phosphorus levels of agricultural soil under barley cultivation irrigated with treated wastewater

direct use of raw urban sewage for agricultural irrigation may result in many harmful consequences. therefore, wastewater treated through different technologies is preferred for reuse, especially in the water-limited areas. the purpose of this study was to compare the use of treated municipal sewage effluent compared to well water on the nitrate and phosphate concentrations in agricultural soil under barley cultivation. for this purpose, a plot of farmland with an area of ​​2000 square meters was divided into two equal parts of 1000 square meters, and for one growing season, one part was irrigated with well water and the other part was irrigated with treated waste water, while the quality of these two water sources was also determined in the laboratory. a total of 28 soil samples were also collected from each of the two plots (totally soil 56 samples) from the layer 0-20 cm and analyzed in the laboratory. inverse distance weighting interpolation method was also used to investigate the spatial distribution of the soil properties. the results showed that the average concentrations of soil phosphate, potassium and sodium measured in the treated wastewater were much higher than of well water and the use of treated urban wastewater significantly increased ammonium, phosphate and nitrate concentrations, and total nitrogen of the soil. in addition, the use of treated municipal wastewater for irrigation could improve the yield of barley (hordeum vulgare) compared to wastewater treatment. it is noteworthy that proper management in the use of treated wastewater and the selection of plants are important which can minimize the harmful effects of using treated wastewater on soil characteristics and crop yield. background and objective: wastewater obtained from water consumption in human daily life consists of 99.9% water and 0.1% mixture of suspended mineral, organic and gases (3). therefore, the use of wastewater and sewage in the cultivation of crops can reduce the need to use chemical fertilizers (1). considering the importance of food chain health in the development of sustainable agriculture, the aim of this study was to evaluate the changes of nitrogen and phosphorous concentrations in the soil irrigated with treated wastewater compared to well water in a farmland under barley cultivation. methods: soil sampling was conducted in a farmland located in the north of boukan city and 175 meters away from the treatment plant in an area of 40×50 square meters (2000 square meters) under barley cultivation irrigated with well water. the farmland was divided into two equal parts each 25×40 square meters during one growing season, one part irrigated with well water and the other part with treated wastewater from bookan city wastewater treatment plant. soil samples were obtained from the layer 0-20 cm before crop cultivation and also at the end of the growing season according to grid networks of 5×5 square meters with a distance of five meters from the peripheral border of each of the two lands (totally 56 soil samples including 28 controls and 28 treatments). the quality of irrigation waters was measured based on the standard methods (2). the results of soil physical and chemical properties, irrigation waters and crop yields were processed using spss v. 22 statistical software. pearson’s correlation, duncan’s post hoc and unpaired t tests were used to investigate the relationships between the initial soil physical and chemical properties, the effect of irrigation water sources on the soil properties, and barley yield. in order to investigate the spatial distribution of final soil properties, distribution maps were prepared using the inverse distance weighting interpolation method by arcgis software v. 10.6. results: the average soil ph was greater than 7, and the means of electrical conductivity (ec) and calcium carbonate equivalent were 567.64 µs/cm and 4.75%.