نوع مقاله : مقالات پژوهشی
نویسندگان
دانشگاه شهرکرد
چکیده
کرم های خاکی یکی از مهم ترین جانوران خاک بوده و فعالیت آنها از شاخص های کیفی خاک به شمار می رود. این جانداران ممکن است تحت تأثیر افزودن پسماندهای آلی قرار گیرند. یکی از روش های سریع و آسان برای پایش کیفیت خاک در هنگام کاربرد لجن فاضلاب، استفاده از شاخص های زیستی از جمله فعالیت های میکروبی است. هدف این پژوهش ارزیابی اثر کرم خاکی بر سرعت نیتریفیکاسیون و آمونیفیکاسیون آرژینین به عنوان فعالیت میکروبی در خاک های تیمارشده با لجن فاضلاب شهری بود. تیمارهای آزمایش شامل لجن فاضلاب (بدون لجن و دارای 5/1 درصد لجن شهری)، و کرم خاکی (بدون کرم، آیزنیافتیدا، آلولوبوفورا کالیژینوزا و مخلوط این دو گونه) به صورت فاکتوریل (4×2) در قالب طرح کاملاً تصادفی با سه تکرار بودند. لجن فاضلاب سرعت نیتریفیکاسیون و آمونیفیکاسیون آرژینین را به ترتیب به میزان 7/16 و 5/62 درصد افزایش داد که دلیل آن بالا بودن میزان مواد آلی و عناصر غذایی و همچنین غلظت پایین فلزات سنگین در پسماند آلی به کار برده شده میباشد. تلقیح کرم خاکی نیز این دو شاخص را تحت تأثیر قرار داد (001/0>p). به طور خلاصه، مصرف لجن فاضلاب شهری اثر تحریک کنندگی کرم خاکی را بر فعالیت میکروبی خاک کاهش داد که این کاهش در حضور گونه ی آیزنیافتیدا (اپی ژئیک) به دلیل تغذیه از لجن فاضلاب محسوس تر بود. علاوه بر این، اثر متقابل دو گونه ی کرم خاکی اغلب جمع پذیر (بدون اثر متقابل) بود.
کلیدواژهها
عنوان مقاله [English]
Earthworm Effects on Nitrification Rate and Arginine Amonification in a Calcareous Soil Amended with Urban Sewage Sludge
نویسندگان [English]
- Hanye Jafari Vafa
- Fayez Raiesi
- Alireza Hosseinpur
- Zohre Karimi
Shahrekord University
چکیده [English]
Introduction: Earthworms are among the most important organisms in soil and their activities can be an indicator of soil quality. These organisms may be influenced by organic wastes application such as sewage sludge and subsequently affect soil quality. One of the quick and easy methods for soil quality monitoring is the use of biological indicators such as microbial activity. It is due to their quick response to changes in the environment. The purpose of this study was to evaluate the effect of earthworms on nitrification rate and arginine ammonification as microbial activity in a calcareous soil amended with urban sewage sludge.
Materials and Methods: The studied soil was sampled from Shahrekord University land and sewage sludge belonged to the refinery sludge ponds of shahrekord. Based on dry weight, this organic waste had carbon and nitrogen, approximately 67 and 110 times more than tested soil, respectively. The organic waste in terms of quality and heavy metal concentrations was in class A. Experimental treatments were sewage sludge (without and with 1.5% sewage sludge) and earthworm (no earthworm, Eiseniafoetida from epigeic group, Allolobophracaliginosa from endogeic group and a mixture of the two species) as 2×4 full factorial experiment arranged in a completely randomized design with three replications. After applying sewage sludge, the pots were irrigated three months to achieve a balance in the soil. An adult earthworm per kg of soil was added and in the mixed treatments comparison species were 1:1. To prevent the exit of earthworms, the pots was closed with a thin lace. At the end of the experiment, soil was completely mixed. Part of it was stored in the refrigerator to measure the microbiological parameters. Chemical properties were measured by the air-dried soil. The effectiveness of a factor in the observed changes is shown by partial effect size (Tabachnick and Fidell 2012). So, partial effect size (Eta2p) for each source of variation (SS, earthworm and SS×earthworm) was calculated.
Results Discussion: According to Eta2p, the role of sewage sludge application to increase total nitrogen was almost twice the earthworm and had a greater effect on the property. Because of low concentrations of heavy metals and high nutrient in sewage sludge, it increased nitrification rate and arginine ammonification by 16.7 and 62.5 percent, respectively. Considering that the indices represent microbial biomass activity, so we can say sewage sludge application increased theri activities. Sewage sludge application increased total nitrogen, because provided the substrate for heterotrophic bacteria. Consequently, ammonium production improved and stimulated activity of Nitrosomonas and Nitrobacter. There was a positive and significant correlation between total nitrogen, arginine ammonification and nitrification rate, that confirmed the occurrence of this process. Earthworm inoculation affected these two indicators (p
کلیدواژهها [English]
- Arginine Amonification
- Earthworm
- Nitrification Rate
- Sewage sludge
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