Environmental Erosion Research

fa تعیین عوامل مؤثر بر حساسیت خاک به تشکیل اندوده سطحی با استفاده از تحلیل آماری چند متغیره Determining the Effective Factors on Soil Susceptibility to Surface Sealing Using Multivariate Statistical Analysis مدیریت و کنترل اثرات فرسایش محیطی مستخرج از پایان‌نامه / رساله / طرح پژوهشی این پژوهش با هدف ارزیابی عوامل مؤثر بر حساسیت خاک به تشکیل اندوده سطحی انجام شد. برای اجرای این تحقیق، هشتاد نمونه خاک (20-0 سانتی‌متری) از دشت کوار استان فارس تهیه شد و بعد از برداشت، در هوا خشک و از الک دو میلی‌متری عبور داده شد. سپس پارامترهای توزیع اندازه ذرات، رطوبت، ماده آلی، هدایت الکتریکی و pH عصاره اشباع خاک اندازه‌گیری شد. همچنین میانگین وزنی و هندسی قطر خاکدانه‌ها، کربنات کلسیم معادل، ابعاد فرکتالی ذرات خاکدانه به طول یک سانتیمتر (مدل‌های ریو- اسپوزیتو، بارتولی و تایلر)، درصد اشباع رطوبتی، سدیم، کلسیم و منیزیوم تعیین ‌شد. در ادامه، نمونههای دستنخورده با استفاده از استوانه‌های فلزی تهیه شد و پس از اشباع در دستگاه بار افتان قرار گرفت، سپس مقدار هدایت هیدرولیکی اشباع نمونه&lrm;ها اندازه‌گیری شد. ارزیابی حساسیت خاک به تشکیل اندوده، با شاخص‌های پایداری ساختمان خاک (SI)، حساسیت نسبی به تشکیل اندوده سطحی (RSI)، سله‌بندی (CI)، پایداری مرطوب خاکدانه‌ها (WAS)، مقاومت فروروی (PR)، حساسیت به سله بستن (CSI) و قوام (C5- C10) انجام شد. از روش‌های آماری چند متغیّره (تجزیه خوشه‌ای، تجزیه تابع تشخیص و همبستگی کانونیک) نیز استفاده شد. همچنین بر اساس ماتریس ساختار مشخص شد که شاخص‌های ,CI SI و CSI از مهمترین شاخص‌هایی است که به تفکیک این دو گروه از یکدیگر منجر میشود. بیشترین همبستگی کانونی در درجه اول به ماده آلی سپس به رس تعلق دارد. دو شاخص پایداری ساختمان خاک (SI) و شاخص سله‌بندی (CI) نیز از مهمترین شاخص‌هایی است که در مقایسه بین شاخص‌ها، بیشترین همبستگی را به خود اختصاص میدهد. مهمترین متغیرهای تأثیرگذار بر شاخص‌های ارزیابی اندوده سطحی ـ که به تفکیک دو گروه، ارائه تابعی با قابلیت بالا و بیشترین همبستگی کانونی منجر میشود ـ ابتدا ماده آلی سپس رس است.   1-Introduction Soil surface sealing is mostly influenced by the specific prevailing conditions during its formation, and the variables affecting soil surface sealing are the physical characteristics of the soil, the chemical conditions of the soil-water system, the characteristics of rain, and the initial and boundary conditions of the flow (Mualem et al, 1990). It is a common phenomenon in most soils of Iran due to arid and semi-arid climate, weak vegetation and loose soil aggregates. In Kowar plain, as an important Agricultural pole of Fars province, it is very important to determine the factors affecting the formation of surface sealing, to identify the most important characteristics of the soil in controlling the surface sealing formation, and to provide a suitable index to determine the sensitivity of the soil to this formation based on the characteristics of soil erosion, which are very important issues and have been addressed in this research study. 2-Methodology To carry out this research, 80 samples (0-20 cm) were selected from Kowar plain with a variety of physical and chemical characteristics, and after sampling, the samples were air dried and passed through a 2 mm sieve. Then, the parameters of particle size distribution, humidity, organic matter, electrical conductivity and pH of saturated soil extract were measured. In addition, the average weight and geometric mean diameter of soil aggregates, calcium carbonate equivalent, fractal dimensions of one-centimeter soil particles (Bartoli, et al, 1991), percentage of moisture saturation, sodium, calcium and magnesium were determined. The saturated hydraulic conductivity of the samples were measured and the evaluation of soil sensitivity to the surface sealing with seven different indices of SI, RSI, CI, WAS, PR (Permeability Resistance), CSI,   C5-C10 had been performed. Also multivariate statistical methods (cluster analysis, discriminant analysis and canonical correlation) were used for conducting the required analyses. 3-Result  After conducting the multivariate statistical method investigations, the results of cluster analysis led to the creation of a discriminant function with a chi-score of 12.73 reaching significance at the probability level of 0.001. This function completely showed the power (ability) to create separation between the two cluster analysis result groups. The organic matter was the most important primary variable that separated these two groups from each other and was significant at the probability level of 0.001. Based on the structure matrix, it was determined that CI, SI and CSI indexes with coefficients of 0.85, 0.58 and 0.30, respectively, are among the most important indices in the separation of these two groups. The performed canonical correlation provided a canonical function with a correlation of 0.99 and a chi score of 626.2. The highest canonical correlation belongs to primarily organic matter and then to clay. Two indices of Soil Stability Index (SI) and Crusting index (CI) were the most important indices having the highest correlation level among the indices. The most important variables influencing the evaluation indices of the sealing surface in the two group’s separation were organic matter and clay, which provided a function with high capability and the highest canonical correlation, respectively. 4-Discussion & Conclusions   The highest coefficient of variation is related to the mass of soil particles with a length of one centimeter (Bartoli model) and the highest canonical correlation in the first degree belongs to the organic matter and clay, it also shows the most important variables, with the highest correlation between these two variables with the mentioned indicators (CI,SI). In addition, two indices of SI and CI were the most important indices having the highest correlation among the indices. The results of cluster analysis, the discriminant function analysis and canonical correlation showed that the most important variables affecting the sealing surface evaluation indices in separating two groups and providing a function with high capability and the highest canonical correlation are organic matter and clay, respectively.  Also based on the structure matrix, the crusting index and aggregate stability are the most important indices that separate the two groups. In fact, the main samples differentiating factors in terms of the sealing surface are the above named indices. Organic matter and soil stability indexes have become significant with a very high correlation and showing a better justification of this indicator (SI) with the characteristics of the soil in determining the sensitivity of the soil to the seal structural formation layer.   آنالیز خوشه‌ای, اندوده سطحی, پایداری خاکدانه‌ها, حساسیت خاک, همبستگی کانونیک. Aggregate stability, canonical correlation, cluster analysis, soil sensitivity, surface sealing. 112 130 http://magazine.hormozgan.ac.ir/browse.php?a_code=A-10-916-1&slc_lang=fa&sid=1 Zhila Asadi Fard ژیلا اسدی فرد zh.asadifard@gmail.com 10031947532846008235 10031947532846008235 Yes Department of Soil Science and Engineering, University of Tabriz, Iran گروه علوم و مهندسی خاک دانشگاه تبریز Abbas Ahmadi عباس احمدی a_ahmadi@tabrizu.ac.ir 10031947532846008236 10031947532846008236 No Soil Science and Engineering Department, University of Tabriz, Iran گروه علوم و مهندسی خاک، دانشگاه تبریز Ali Asghar Jafarzadeh علی اصغر جعفرزاده ajafarzadeh@tabrizu.ac.ir 10031947532846008237 10031947532846008237 No Department of Soil Science and Engineering, University of Tabriz, Iran گروه علوم و مهندسی خاک، دانشگاه تبریز Alidad Karami علیداد کرمی alidad_karami@yahoo.com 10031947532846008238 10031947532846008238 No Agricultural Research Center of Fars Province, Iran مرکز تحقیقات کشاورزی استان فارس Siamak Alavikia سیامک علوی کیا ss.alavikia@tabrizu.ac.ir 10031947532846008239 10031947532846008239 No Department of Plant Breeding, University of Tabriz, Iran گروه اصلاح و نباتات دانشگاه تبریز