نوع مقاله : مقاله پژوهشی
نویسنده
استاد، پژوهشکده حفاظت خاک و آبخیزداری، سازمان تحقیقات، آموزش و ترویج کشاورزی، تهران، ایران
چکیده
یکی از روش‌های مطالعه فرسایش و حفاظت خاک، استفاده از کرت‌های فرسایش است که با ابعاد مختلف و در عرصه‌های طبیعی و یا در آزمایشگاه‌ها ایجاد می‌شوند. خطاهای فاحش در زمان نمونه‌برداری از مخلوط رواناب و رسوب مخازن انتهای این کرت‌ها و نتیجه‌گیری‌های غلط از آزمایش‌هایی که در این کرت‌ها صورت می‌گیرند، امور رایجی است که باید از آن‌ها اجتناب کرد. تحقیقات کمی در رابطه با نحوه نمونه‌برداری از این مخازن و کاهش خطاهای ناشی از آن صورت گرفته است. در این تحقیق، به بررسی افزایش دقت نمونه‌برداری با قرار دادن سطل در مخزن و روش استفاده از بطری پرداخته شد. به این منظور، پس از تهیه دو مخزن 220 لیتری، با ایجاد غلظت‌های به‌ترتیب پنج، 10 و 20 گرم در لیتر در مخزن اول و انتقال محلول حاصل به مخزن دوم که در ارتفاع پایین‌تری از مخزن اول قرار گرفته، با قرار دادن سطل 20 لیتری در زیر لوله وارد کننده محلول در مخزن دوم، اقدام به تله‌اندازی ذرات درشت‌دانه شد. محتویات سطل در آزمایشگاه پس از خشک شدن به‌طور جداگانه توزین شدند. با مخلوط کردن محلول مخزن دوم، اقدام به نمونه‌برداری به وسیله بطری‌های یک لیتری به تعداد سه تکرار برای هر غلظت شد. نمونه‌برداری‌های فوق بدون قرار دادن سطل به‌عنوان شاهد نیز صورت گرفت. بررسی معنی‌دار بودن اثر غلظت‌ها بر مقدار خطا با تجزیه واریانس طرح آزمایشات بلوک تصادفی صورت گرفت. نتایج نشان داد که بین غلظت‌های به‌دست آمده در آزمایش با سطل و بدون سطل اختلاف معنی‌داری در سطح یک درصد وجود دارد. در حالت بدون سطل خطای نمونه‌های پنج، 10 و 20 گرم در لیتر به ترتیب 63.13، 78.40 و 73.97 درصد و در حالت استفاده از سطل به ترتیب 15.90، 15.07 و 4.83 درصد بودند. متوسط خطا در هر سه غلظت در حالت بدون سطل 71.83 درصد و در حالت استفاده از سطل 11.93 درصد بود.
کلیدواژه‌ها
عنوان مقاله [English]
Sampling accuracy of runoff and sediment from erosion plot tanks using bucket
نویسنده [English]
- Davoud Nikkami
Professor, Soil and Water Conservation Research Institute, Agricultural Research and Training Organization, Tehran, Iran
چکیده [English]
Using erosion plots is a way to research on soil erosion and conservation that with different dimensions, which are constructed in the natural arenas or in laboratories. Mistakes and false conclusions are common task that should be avoided when sampling runoff and sediment from the tanks of these plots. A few researches have been done on the ways of sampling from these tanks and reducing the errors. In this study, the accuracy of sampling was investigated by placing a bucket in the tank and using bottle sampling. For this purpose, two 220 liter tanks were used. In the first tank located at the upper level, concentrations of sediment were prepared for five, 10 and 20 grL-1 and the mixture of runoff and sediment was transferred to the second tank. Coarse particles were trapped by a bucket of twenty liters placed underneath the importer tube in the second tank. The contents of the bucket were weighed in the laboratory after drying. Also, sampling of the second tank contents was carried out after mixing the solution and using one-liter bottles in three replications per each concentration. Sampling was also done without placing the bucket as a witness. The significance of the effect of concentrations on the error value was defined by analysis of variance through a random block design scheme. Results demonstrated that there was a significant difference between the concentrations obtained in the experiment with bucket and without bucket at a level of one percent. Without using bucket, the amount of errors were 63.13, 78.40 and 73.97 percent for 5, 10 and 20 gr.L-1 concentrations, respectively and with using bucket they were 15.90, 15.07 and 4.83 percent. The mean errors in all concentrations were 71.83 and 11.93 percent without and with using buckets, respectively.
کلیدواژه‌ها [English]
- Bottle sampling
- Sampling error
- Sediment concentration
- Soil erosion
- Traping coarse particles
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