بررسی توزیع کربن‌آلی و برخی خصوصیات فیزیکی مرتبط با پایداری خاک در منطقه ایوریق اردبیل

مطالعه شاخص های پایداری برای سلامت خاک و مدیریت خطرات فرسایش حیاتی است. پایداری خاک و تخمین استعداد فرسایش اراضی از کربن آلی، رس و سیلت قابل انتشار در آب (wdc و wdsi) متاثر شده و از روی برخی شاخص ها مانند شاخص های نسبت پراکندگی(dr)، نسبت پراکندگی رس (cdr)، شاخص انعقاد رس (cfi) و شاخص پایداری ساختمان (ssi) و فرسایش پذیری خاک (k) تخمین زده می شود. بنابراین، این پژوهش با هدف بررسی توزیع کربن آلی و برخی خصوصیات فیزیکی مرتبط با پایداری خاک در منطقه ایوریق اردبیل انجام شد. لذا، تعداد 100 نمونه (صفر تا 30 سانتی متر) از زمین‌های کشاورزی منطقه ایوریق تهیه و مختصات جغرافیایی توسط gps ثبت گردید. پس از هوا خشک کردن و عبور دادن از الک، رطوبت جرمی، کربن آلی، بافت خاک، رس و سیلت قابل انتشار در آب در بخش ریز اندازه گیری و سپس شاخص های dr و cdr و cfi و ssi و k محاسبه گردید. در نهایت، همبستگی پیرسون بین داده های خروجی توسط spss برقرار و نقشه کلاس بندی پارامترها با استفاده از نرم افزار arc gis رسم شد. نتایج نشان داد که میانگین مقادیر oc، wdc،wdsi ، dr، cdr، cfi، ssi و k در 100 نمونه از منطقه به ترتیب برابر 0.79، 12، 45، 0.93، 0.47، 0.53، 2.23 درصد و 0.310 مگاگرم ساعت در هکتار بر مگاژول میلی متر در هکتارمی باشد. حداقل مقادیر به دست آمده برای پارامترهای dr و cdr و wdc و wdsi و k به ترتیب برابر 0.73، 0.06، 2، 27 و 0.47 بود و حداکثر مقادیر به دست آمده برای پارامترهای ssi و cfi و oc به ترتیب برابر 4.45، 0.94 و 1.56 بود، لازم به ذکر است هر چه میزان شاخص های dr و cdr و wdc و wdsi و k کمتر باشد و در مقابل، هر چه میزان شاخص های  ssi و cfi و oc بیشتر باشد، پایداری خاک بالا بوده و در برابر فرسایش مقاومت بیشتری دارد. با توجه به داده ها، می توان نتیجه گرفت که پایداری خاک در این منطقه ضعیف بوده و این اراضی در برابر عوامل فرسایشی به شدت آسیب پذیر می باشند.کربن آلی تمامی پارامترها و شاخص های مورد مطالعه را تحت تاثیر خود قرار می دهد و با بالا بردن مقاومت خاک در برابر عوامل فرسایشی ، پایداری خاک را افزایش می دهد.

investigating the distribution of organic carbon and some physical properties related to soil stability in ivriq region of ardabil

1- introductionevaluating soil stability indices are vital for understanding soil health and managing erosion risks. soil stability is influenced mostly by soil organic carbon (soc), water dispersible clay (wdc) and water dispersible silt (wdsi) content and can be estimated by some indices such as dispersion ratio (dr), clay dispersion ratio (cdr), clay flocculation index (cfi), structural stability index (ssi) and soil erodibility factor (k ). soil organic carbon is considered as a very valuable and key resource for estimation of soil erosion. organic carbon plays a key role in soil resistance to erosive factors and soil structure stability. studying the factors affecting soil erosion and identifying areas prone to erosion is essential for proper soil management and use, optimal allocation of soil and water resources, pollution prevention and loss of these two very valuable resources. therefore, this research was conducted to investigate the distribution of organic carbon and some physical properties related to soil stability in the ivrig region of ardabil.2- methodologythis research was conducted on agricultural lands of ivrig village of hir in ardabil (with a geographical location of 38º 10’ north latitude and 48º 31’ east). wheat, barley, potatoes, beans, alfalfa, and chickpeas were the dominant cultivated crops. the average, minimum and maximum annual temperature is 9.8, 3.4 and 15.7 c0, respectively, and its annual rainfall is 287.1 mm. 100 soil samples (0-30 cm) were collected from agricultural lands in a nearly regular and undisturbed grid pattern. after air drying and passing through a sieve, moisture (ɵm), organic carbon and soil texture were measured by weighting, walkely-black and hydrometer methods. also, water dispersible clay and silt were measured by hydrometer method without hexametaphosphate. soil stability indices (dr, cdr, cfi, ssi) and soil erodibility factor (k) were calculated using related equations. pearson correlation was also established between output data using spss and a parameter classification map was drawn using arc gis software.3- resultsresults showed that average values ​​of  oc, wdc and wdsi content were 0.79, 12 and 45 %.  the organic carbon content in 76 % of studied soils was lower than 1 %. soil stability indices calculated as 0.93, 0.47, 0.53 and 2.23 percentage for dr, cdr, cfi and ssi, respectively. the average content of soil erodibility content (k) was calculated 0.310. the lower values ​​of  dr, cdr, wdc, wdsi and k indices and, in contrast, the higher values ​​of ssi, cfi and oc indices refers to high soil stability and high resistance to erosion. the results of pearson’s correlation showed that there is a negative and significant correlation between soil organic carbon and sand and the dispersion ratio (dr).  in contrast, there was a positive and significant correlation between soil organic carbon and total silt and soil structural stability index (ssi) at the probability level of 1 %.  in our research, a negative and significant correlation was found between the soil erodibility factor (k) and dr index and total sand at the probability level of 1%. soil erodibility factor (k) significantly correlated with total and water dispersible (wdsi) silt at the probability level of 1%.  4- discussion & conclusionsorganic carbon is depleted in ivrig agricultural soils over time (oc<1 in 76 % of soils). therefore, it is expected that the soil aggregation process is weak in this area and even according to the results of the experiments, it is possible to assume that some soil aggregates have disintegrated. for these reasons, the amount of water dispersible clay and silt was high in the studied samples. the stability and strength of the soil enhances by increasing the amount of ssi, cfi, and oc indices and decreasing the amount of dr, cdr, wdc, wdsi, and k indices. therefore, soils with high structural stability are resistant to erosion. according to our data (lower values for ssi, cfi and oc), it can be concluded that the soil structure was weak in ivrig region soils and these lands are highly vulnerable to erosion factors because of higher values for dr, cdr, wdc, wdsi and soil erodibility factor (k). it seems that organic carbon affects all the studied parameters and indicators and increases the soil’s resistance to erosion by increasing the stability of the soil. increasing soil organic carbon and adopting appropriate agricultural management, including the use of cultivation methods without tillage and minimal tillage, are suitable solutions to protect these lands.