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بررسی رابطه بین توزیع اندازه ذرات و معماری منافذ خاک تحت سطوح مختلف تراکم با استفاده از توموگرافی کامپیوتری اشعه ایکس | ||
| پژوهش های خاک | ||
| مقالات آماده انتشار، پذیرفته شده، انتشار آنلاین از تاریخ 31 شهریور 1405 | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22092/ijsr.2026.373992.834 | ||
| نویسندگان | ||
| عطااله خادم الرسول* 1؛ مجتبی شیرازی2؛ لارس مونکلوم3 | ||
| 1خاکشناسی، دانشکده کشاورزی، دانشگاه شهید چمران اهواز | ||
| 2گروه خاکشناسی، دانشکده کشاورزی دانشگاه شهید چمران اهواز، ایران | ||
| 3دپارتمان اگرواکولوژی، دانشگاه آرهوس دانمارک | ||
| چکیده | ||
| این پژوهش اثر تراکم ناشی از تردد ماشینآلات در سامانههای کشاورزی مکانیزه را بر توزیع اندازه ذرات و معماری سهبعدی شبکه منافذ خاک بررسی کرد. برای این منظور، از آنالیز پراش لیزری (PSA) و توموگرافی کامپیوتری پرتو ایکس (X-Ray CT) استفاده شد. نمونهبرداری در سه تیمار شامل قبل از برداشت (BH)، پس از برداشت با 75 درصد ظرفیت سبد حمل نیشکر (AH-75%) و پس از برداشت با 100 درصد ظرفیت سبد حمل نیشکر (AH-100%) و در سه تکرار انجام گرفت. شاخصهای توزیع اندازه ذرات و ویژگیهای هندسی منافذ از دادههای PSA و تصاویر سهبعدی CT استخراج و روابط آنها با تحلیل همبستگی و مؤلفههای اصلی (PCA) بررسی شد. نتایج نشان داد تراکم موجب افزایش شاخصهای D50، GMD و MWD و کاهش Span شد؛ این تغییرات نشاندهنده بازآرایی ذرات و یکنواختتر شدن توزیع اندازه آنها بود. بیشترین تغییر در تیمار AH-75% مشاهده شد که احتمالاً با رطوبت خاک هنگام تردد مرتبط است. همچنین، ضخامت منافذ در تیمارهای متراکم اندکی کاهش یافت، اما تعداد منافذ بهطور چشمگیری افزایش پیدا کرد که بیانگر بازآرایی شبکه منفذی و تبدیل منافذ بزرگتر به منافذ کوچکتر است. تحلیل PCA نشان داد دو مؤلفه نخست 59/86 درصد واریانس کل دادهها را تبیین کردند و متغیرهای PSA و CT دو گروه نسبتاً متمایز مربوط به فاز جامد و فاز منفذی خاک تشکیل دادند. در مجموع، PSA و CT ابزارهایی مکمل برای ارزیابی ساختمان خاک هستند و کاربرد همزمان آنها میتواند شناخت جامعتری از تغییرات ساختاری ناشی از تراکم و کیفیت فیزیکی خاک در شرایط کشاورزی مکانیزه فراهم کند. | ||
| کلیدواژهها | ||
| آنالیز اندازه ذرات؛ تراکم خاک؛ توموگرافی؛ ساختمان خاک؛ شبکه منافذ خاک | ||
| عنوان مقاله [English] | ||
| Investigating the Relationship between Soil Particle Size Distribution and Pore Architecture under Different Compaction Levels Using X-ray Computed Tomography | ||
| نویسندگان [English] | ||
| Ataallah Khademalrasoul1؛ Mojtabaa Shirazi2؛ Lars Munkholm3 | ||
| 1Soil Science, Agriculture, Shahid Chamran University of Ahvaz | ||
| 2Dep. of soil science, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Iran | ||
| 3Dep. of Agroecology, Aarhus University of Denmark | ||
| چکیده [English] | ||
| Background and Objective: Soil compaction induced by agricultural machinery is a major threat to soil physical quality, as it alters both particle arrangement and pore-network architecture. Although particle size distribution (PSD) and pore characteristics are fundamental descriptors of soil structure, their responses to compaction and the linkage between the particle and pore domains remain insufficiently understood. Laser diffraction particle-size analysis (PSA) provides quantitative indices of particle-size organization, whereas X-ray computed tomography (CT) enables three-dimensional characterization of soil pore architecture. Integrating these complementary approaches may therefore provide a more comprehensive understanding of structural changes induced by mechanical loading. Accordingly, this study aimed to (i) quantify the response of PSD indices and three-dimensional pore characteristics to different levels of machinery-induced compaction, and (ii) elucidate the relationships between particle-domain and pore-domain properties using correlation and principal component analyses. Materials and Methods: The study was conducted in a sugarcane field located in the Debel Khozaei Agro-Industry Company, Khuzestan Province, Iran. Soil samples were collected from three treatments with three replications: before harvesting (BH), after harvesting with 75% wagon load capacity (AH-75%), and after harvesting with 100% wagon load capacity (AH-100%). Undisturbed soil cores were sampled from the 0–25 cm depth within machinery traffic lanes. Particle size distribution was determined using laser diffraction analysis, and the indices D10, D50, D90, geometric mean diameter (GMD), mean weight diameter (MWD), Span, coefficient of uniformity (Cu), and coefficient of curvature (Cc) were calculated. Three-dimensional pore characteristics were quantified from X-ray CT images, including pore thickness, maximum pore thickness, and pore number. Statistical analyses were performed using R software. Correlation analysis and principal component analysis (PCA) were applied to evaluate relationships among PSA and CT-derived variables. Results and Discussion: Soil compaction significantly affected particle size distribution indices, with the highest D50, GMD, and MWD values observed in AH-75%, indicating substantial changes in particle arrangement and aggregate organization. D50 increased from approximately 1.07 μm in BH to 7.34 μm in AH-75% and 5.26 μm in AH-100%, while Span decreased in compacted treatments, indicating a more uniform particle size distribution. X-ray CT showed a slight reduction in pore thickness but a marked increase in pore number under compaction. Average pore thickness decreased from approximately 0.0151 cm in BH to 0.0140 and 0.0142 cm in AH-75% and AH-100%, respectively, whereas pore number increased from about 146,000 to 462,000 and 413,000, respectively. Thus, compaction promoted the fragmentation of larger pores into a greater number of smaller pores rather than eliminating pore space. Notably, the most pronounced structural changes occurred under AH-75% despite its lower applied load than AH-100%, highlighting the critical role of soil moisture during machinery traffic; higher moisture likely enhanced particle rearrangement and pore-network reorganization, increasing soil susceptibility to compaction. Principal component analysis showed that the first two components explained 86.59% of the total variance, with PSA-derived variables (D10, D50, D90, GMD, and MWD) primarily associated with PC1 and pore-related variables (Thickness, Max Thickness, and Number of Pores) with PC2. This separation indicates that PSA and CT characterize distinct but complementary aspects of soil structure. Conclusion: The results demonstrated that soil compaction simultaneously affects both the particle domain and pore domain of soil structure. Compaction increased effective particle size indices while reducing pore thickness and increasing pore number, reflecting substantial reorganization of the soil pore network. Soil moisture played an important role in determining the magnitude of structural changes, with the AH-75% treatment exhibiting the strongest response. Principal component analysis confirmed that PSA and CT characterize distinct structural dimensions of soil and should be considered complementary tools rather than alternative methods. The combined application of laser diffraction analysis and X-ray computed tomography provides a more comprehensive assessment of soil structural degradation and physical soil quality under compaction conditions. | ||
| کلیدواژهها [English] | ||
| Soil structure, Soil compaction, Particle size analysis, Tomography, Soil pore network | ||
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