Environmental Erosion Research

fa کاربرد نقشه های رقومی کربن آلی و رس خاک در بررسی پایداری ساختمان خاک Using Digital Maps of Soil Organic Carbon and Clay for Evaluating Soil Structure Stability روشهای نوین و دقیق در تهیّه نقشه فرسایش (سنجش از دور و سیستم‌های اطلاعات جغرافیایی) مستخرج از پایان‌نامه / رساله / طرح پژوهشی پایداری خاکدانه که از شاخص‌های ارزیابی کیفیت خاک است یکی از عوامل اصلی پایداری اراضی می‌باشد. از آنجایی‌که اندازه‌گیری این خصوصیت به‌ویژه در سطح کلان همراه با دشواری‌هایی است، استفاده از شاخص‌های برآوردی آن می‌تواند در تسهیل مطالعات نقش داشته باشد. در پژوهش حاضر که در بخشی از اراضی شمال‌غرب ایران انجام شد، تعیین این خصوصیت با استفاده از شاخص نسبت کربن آلی به رس خاک در دستور کار قرار گرفت. بدین منظور شاخص مذکور برای پنج عمق استاندارد از محدوده مورد مطالعه با تلفیق نقشه‌های رقومی رس و کربن آلی تهیه شده برای منطقه به‌دست آمد. برای بررسی کارایی شاخص حاصل از نقشه ثانویه، در 15 نقطه مطالعاتی برای عمق‌های استاندارد نیز شاخص پایداری خاکدانه طبق روش آزمایشگاهی تعیین و سپس از طرح فاکتوریل کاملاً تصادفی با 15 تکرار (نقطه مطالعاتی) برای هر یک از 5 عمق استاندارد برای مقایسه‌ مقادیر آزمایشگاهی و مستخرج از نقشه ثانویه استفاده گردید. تجزیه‌های آزمایشگاهی نشان داد که محدوده مقدار رس در منطقه 02/12 تا 25/65 درصد و برای کربن آلی 18/0 تا 42/3 درصد می‌باشد. همچنین حداقل و حداکثر مقدار شاخص پایداری خاکدانه 34/8 تا 17/47 به‌دست آمد. از بررسی تغییرات عمقی سه ویژگی مورد بحث نتیجه شد که با افزایش عمق از مقدار کربن آلی خاک کاسته و در مقابل مقدار رس و پایداری خاکدانه افزایش یافت. تجزیه‌های آماری بیان‌گر غیرمعنی‌داری تفاوت مقدار شاخص پایداری خاکدانه حاصل از اندازه‌گیری مستقیم و مستخرج از نقشه ثانویه بود. بنابراین نقشه ثانویه حاصل از تلفیق نقشه‌های رقومی پایه کربن آلی و رس نیز نمایش قابل قبولی از توزیع مکانی وضعیت پایداری خاکدانه‌ها در عمق‌های استاندارد مورد مطالعه ارائه می‌کند. لیکن استفاده از شاخص‌های جامع‌تر همراه با توجه به اهمیت و نسبت فاکتورهای دخیل در شاخص و نیز توجه به عوامل ثانویه مشتق از ویژگی‌های خاک مثل افق‌های مشخصه خاک و یا الگوهای عوامل خارج از خاکرخ می‌تواند در افزایش دقت کار مؤثر واقع شود. در نهایت تحقیق حاضر تأکید بر استفاده از نقشه رقومی ویژگی‌های خاک برای تولید نقشه‌های شاخص‌های خاک به‌منظور افزایش بهره‌وری مطالعات مدیریت منابع خاک دارد. <div dir="ltr"></div> 1- Introduction The lands sustainability depends on soil stability as one of its components. Aggregate stability is an index for evaluating soil quality and the main factor of soil stability. Soil organic matter and clay are known as the most important soil properties that play a main role in the stability of soil aggregates. Therefore, in recent studies, the ratio of soil organic carbon to clay has been expressed as an indicator of soil aggregate stability. In a large scale, land management based on soil properties such as soil aggregate stability, requires the preparation of soil aggregate stability index maps. In this regard, Digital Soil Mapping can be a useful tool. Generating soil characteristics maps from combining digital maps of soil routine properties, can be a suitable solution to facilitate soil survey studies. The present research work was designed to investigate the possibility of using secondary maps produced from the combination of soil properties maps that focus on the condition of land sustainability based on soil aggregate stability. 2- Material and methods The present research work, which was conducted in northwestern Iran, was completed in line with a previous study in which the preparation of a digital map of clay and soil organic carbon was one of its results. The soils of study area are Inceptisols and Aridisols which are under agriculture land use. According to the main aim of the study, aggregate stability was determined by two methods for 15 study points at five standardized depth intervals (H1: 0-5, H2: 5-15, H3: 15-30, H4: 30-60, and H5: 60-100 cm) based on the GlobalSoilMap protocol. Firstly, the aggregate stability index, the ratio of soil organic carbon to clay content, was extracted from the map generated by combining a digital map of clay and soil organic map according to the formula of mentioned index. Also, aggregate stability was determined in the laboratory by wet aggregate stability method for study points. Finally complete randomized factorial designed at the same five standard depths as the statistical method to assess the performance of the generated map based on soil aggregate stability index. 3- Results It was found that the clay and organic carbon content were ranged from 12.02 to 65.25 and 0.18 to 3.42 all over the study area. Also, descriptive statistics of aggregate stability by laboratory analysis revealed the min and max values were 8.34, and, 47.17 respectively. The results showed that with depth increment, soil organic carbon decreased while clay and aggregate stability increased. The digital maps of soil organic carbon and clay which produced in previous study showed that there aren’t distinct trends around different direct of study area. The result of generated map from combining based on aggregate stability index, the ratio of soil organic carbon to clay content, showed that with depth increment, aggregate stability increased. The Kolmogorov–Smirnov (K-S) test, showed that the obtained data for aggregate stability from studied methods do not have a normal distribution. Therefore before statistical analysis, data were normalized by Sin conversion method. The statistical analyses showed that there was no significant difference between directly measured aggregate stability index in laboratory and the data extracted from generated maps. 4- Discussion & Conclusions From the alignment of changes in the aggregate stability index with the clay content and its contradiction with changes in the organic carbon content, it can be concluded that although organic carbon and clay are known to be the main components in aggregates stability, but their ratio can also play an important role in soil aggregates stability. Also, it should be paid to the role of other factors involved in the aggregates stability, such as the diagnostic horizons that contain various salts and particles. According to statistical analysis, although there are differences between aggregate stability index from studied methods, but it is not significant. The final digital map prepared by integrating soil organic carbon and clay demonstrates an acceptable result regarding soil aggregate stability at the studied standardized depths. In this regard, it seems that using of indexes with powerful algorithm and larger number of soil characteristics lead to have higher accuracy and precision in estimating aggregate stability. Finally, it can be concluded that the usage of popular indices with a focus on the importance of contributed environmental covariates for mapping base characteristics responds to soil surveying demands. The present research revealed the crucial role of base maps for preparing key indices to improve the efficacy of soil resource management observations.   پایداری اراضی, ساختمان خاک, کربن آلی, نقشه‌های رقومی Digital maps, Land sustainability, Organic carbon, Soil structure 88 103 http://magazine.hormozgan.ac.ir/browse.php?a_code=A-10-862-2&slc_lang=fa&sid=1 Fatemeh Ghasedi-Yousefabad فاطمه قاصدی یوسف آباد Fatemeh.ghasedi2607@gmail.com 10031947532846009935 0009-0000-6070-4999 No Department of Soil Science, Faculty of Agriculture, University of Tabriz, Tabriz گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه تبریز، تبریز Hossein Rezaei حسین رضائی hossenrezaei@tabrizu.ac.ir 10031947532846009936 10031947532846009936 Yes Department of Soil Science, Faculty of Agriculture, University of Tabriz, Tabriz گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه تبریز، تبریز Farzin Shahbazi فرزین شهبازی Shahbazi@tabrizu.ac.ir 10031947532846009937 10031947532846009937 No Department of Soil Science, Faculty of Agriculture, University of Tabriz, Tabriz گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه تبریز، تبریز Davoud Zarehaghi داود زارع حقی Davoudhaghi@tabrizu.ac.ir 10031947532846009938 10031947532846009938 No Department of Soil Science, Faculty of Agriculture, University of Tabriz, Tabriz گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه تبریز، تبریز