برآورد نسبت پخشیدگی اکسیژن و گذرپذیری هوا از روی مقدار رطوبت خاک

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانش آموخته کارشناسی ارشد علوم خاک، دانشکده کشاورزی، دانشگاه تبریز

2 استاد گروه علوم خاک، دانشکده کشاورزی، دانشگاه تبریز

3 استادیار گروه علوم خاک، دانشکده کشاورزی، دانشگاه تبریز

4 دانش آموخته کارشناسی‏ارشد علوم‏خاک،دانشکده کشاورزی،دانشگاه آزاد اسلامی تبریز

چکیده

پخشیدگی یک گاز در خاک نسبت به پخشیدگی آن در اتمسفر (DP/D0) و نیز گذرپذیری هوا درخاک (Ka) تابع خصوصیات فیزیکی خاک مانند اندازه و پیوستگی منافذ و همچنین تخلخل تهویه­ای است. پخشیدگی گاز در خاک نیز بر اساس خصوصیات شکل، اندازه و پیچ‏خوردگی منافذ و مقدار رطوبت خاک متفاوت می­باشد. در این تحقیق تعداد 30 نمونه خاک از کلاس­های بافتی مختلف بصورت دست­نخورده با استفاده از استوانه فولادی تهیه گردید. در رطوبت­های متعدد مقادیر DP/D0 با روش حالت غیرماندگار پخشیدگی گاز اکسیژن و Ka با روش بار افتان اندازه­گیری شد. در نهایت تغییرات  DP/D0و Ka در رطوبت­های متعدد و رابطه‏ بین آنها به صورت معادله رگرسیونی بدست آمد. نتایج نشان داد که با افزایش میزان رطوبت خاک DP/D0 و Ka بصورت تابع لگاریتمی کاهش یافت به نحوی که حداکثر مقادیر این دو خصوصیت در رطوبت‏های پائین و حداقل آن در رطوبت­های نزدیک اشباع بدست آمد. R2 بدست آمده برای برآورد DP/D0 و Ka (به ترتیب برابر 75/0 و 58/0) نشان داد با فرض ثابت بودن سایر خصوصیات فیزیکی خاک، با اطمینان قابل توجهی می‏توان از این روابط به منظور برآورد DP/D0 از روی مقدار رطوبت خاک استفاده کرد و نیازی به اندازه­گیری مستقیم این دو خصوصیت نمی‏باشد.

کلیدواژه‌ها

عنوان مقاله [English]

Estimating Oxygen Diffusion Ratio and Air Permeability by Using Amount of Soil Moisture

نویسندگان [English]

  • P. Mohammadi 1
  • M. R. Neyshabouri 2
  • Abbas Ahmadi 3
  • N. Balandeh 4
1 Former M.Sc. student of Soil Science Department, Agricultural Faculty, Tabriz University- Tabriz-Iran
2 Professor, Soil Science Department, Agricultural Faculty, Tabriz University- Tabriz-Iran
3 Assistant Professor, Soil Science Department, Agricultural Faculty, Tabriz University- Tabriz-Iran
4 Former M.Sc. student of Soil Science Department,Agricultural Faculty,Islamic Azad University of Tabriz –Iran
چکیده [English]

Gas diffusion ratio in the soil compared to its diffusion in the atmosphere (DP/D0) and air permeability in the soil (Ka) is a function of soil physical characteristic, including pore size, pore continuity, and air porosity. Also, gas diffusion in soil is different based on the shape, moisture content, size, and pore tortuosity. In this study, 30 soil samples from different textural classes were prepared as undisturbed soil using a steel cylinder. At different moisture contents, DP/D0 values were measured with oxygen diffusion unsteady method and Ka was measured using falling head method. Finally, DP/D0 and Ka changes at various soil moisture levels and regression equations showing their relation were obtained. The results indicated that with increasing soil moisture, DP/D0 and Ka decreased as logarithmic function such that the maximum values of these two properties were achieved at low soil moisture and their minimum values at near saturation moisture. The obtained R2 values for DP/D0 and Ka (0.75 and 0.58, respectively) showed that, assuming other soil physical properties remain constant, we could use these relationships to estimate DP/D0 from the amount of soil moisture with relatively good accuracy and considerable reliability, thus, by this method, the direct measurement of these two properties is not required.

کلیدواژه‌ها [English]

  • Oxygen meter
  • Gas diffusion
  • Pore size
  • Soil physical properties

مراجع

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پژوهش های خاک
دوره 27، شماره 4
اسفند 1392
صفحه 583-591

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