نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکتری، گروه علوم خاک، دانشکده کشاورزی، دانشگاه زنجان

2 استاد گروه علوم خاک، دانشکده کشاورزی، دانشگاه زنجان

چکیده

فرسایش پاشمانی نخستین نوع فرسایش آبی بوده که توسط ضربه قطرات باران بر سطح خاک ایجاد می‌شود. قطرات باران می‌توانند ذرات خاک را از جا کنده و جابه‌جا کنند. انتقال ذرات در اثر پاشمان قطرات به عوامل متعددی از جمله نوع خاک و شرایط شیب بستگی دارد. اگرچه اطلاعاتی در مورد نقش این دو عامل در فرسایش پاشمانی در دسترس بوده اما انتخاب‌پذیری ذرات در فرسایش پاشمانی موضوعی است که نیاز به بررسی بیش‌تر به‌ویژه در خاک‌های منطقه نیمه‌خشک دارد. این پژوهش به‌منظور بررسی تغییرات فرسایش پاشمانی و انتخاب‌پذیری ذرات در خاک‌های مختلف تحت تأثیر شیب سطح انجام گرفت. برای این منظور آزمایش در سه خاک با بافت مختلف (لوم، لوم‌رسی و لوم‌رس‌شنی) در چهار شیب (صفر، 10، 20 و 30 درصد) تحت باران شبیه‌سازی‌شده با شدت ثابت 30 میلی‌متر بر ساعت در سه تکرار در مجموع با 36 واحد آزمایشی در قالب طرح کاملاً تصادفی انجام شد. بر اساس نتایج بیش‌ترین مقدار فرسایش پاشمانی در خاک لوم‌رسی (07/105 گرم بر متر مربع در دقیقه) و کم‌ترین مقدار آن در خاک لوم‌رس‌شنی (28/80 گرم بر متر مربع در دقیقه) رخ داد. با افزایش شیب، شدت فرسایش پاشمانی افزایش یافت. به‌طورکلی انتخاب‌پذیری ذرات در اثر پاشمان تحت تأثیر بافت خاک، شیب سطح و برهم‌کنش آن دو قرار گرفت. سیلت حساس‌ترین ذره به پاشمان بود، به‌طوری­که حدود 57 درصد ذرات پاشمان­یافته را در برگرفت و در مقابل شن با حدود شش درصد از سهم پاشمان، مقاوم‌ترین ذره به فرآیند پاشمان بود. در تمامی بافت‌ها (به‌جز بافت لوم) انتخاب‌پذیری ذرات سیلت در سطوح مختلف شیب بیش‌تر از سایر ذرات بود. در خاک لوم انتخاب‌پذیری ذرات رس بیش‌تر از ذرات سیلت بوده که علت این موضوع پایین بودن مقدار ذرات رس در نمونه اولیه خاک لوم بود.

کلیدواژه‌ها

عنوان مقاله [English]

Effect of Surface Slope on the Selectivity of Particles in Splash Erosion in Different Soils

نویسندگان [English]

  • Majid Foroumadi 1
  • Ali Reza Vaezi 2

1 Ph.D. Student of Soil Science, Faculty of Agriculture, University of Zanjan

2 Professor, Department of Soil Science, Faculty of Agriculture, University of Zanjan

چکیده [English]

Abstract
Splash erosion is the first type of water erosion caused by the impact of rain drops on the soil surface. Rain drops can disperse and move soil particles. Particles which transfer is effected by raindrop splash depends on several factors, including the soil type and the slope conditions. Although information on the role of these two agents splash erosion is available, but the selectivity of particles in splash erosion is a subject that needs further investigation, especially in the semi-arid region soils. This study was conducted to investigate the effects of splash erosion and selectivity of particles in different soils under the influence of slope. For this purpose, experiments were carried out in three different soils (Loam, Clay loam, Sandy clay loam) on four slopes (0, 10, 20 and 30%) under a simulated rain with constant intensity of 30 mm.h-1 in three replications, with a total of 36 units in the form of a completely randomized design. According to the results, the highest and the lowest amount of splash erosion were in the clay loam soil (105.07 g.m-2.min-1) and the sandy clay loam soil (80.28 g.m-2.min-1), respectively. With increasing the gradients, the intensity of splash erosion increased. In general, the selectivity of particles in the splash erosion was affected by the soil texture, the slope of the surface, and the interaction between of them. Silt was the most sensitive particle to splash, accounting for almost 57% of the splashed particles, and against the sand with almost 6% contribution to the splash was the most resistive particle. In all textures (except the loam texture), the selectivity of the silt particles at different levels of the gradient was greater than the rest. In the loam soil, clay particles were more selective than the silt particles, most likely due to the lower amount of clay particles in the original soil samples.

کلیدواژه‌ها [English]

  • Aggregate breakdown
  • Impact of raindrop
  • Particle soil distribution
  • Rainfall simulator
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