برآورد فرسايش سطحي خاك با استفاده از روش سزيم - 137 در اراضي زير كشت چاي در شرق گيلان

Estimation of surface soil erosion by Cs-137 method in tea cultivated area in east of Guilan

There are 32000 hectares tea plantation in Guilan Province and about 83% of tea orchards are located in steepy area. For some reasons, erosion is the main problem of these area, which causes heavy soil losses on surface horizons. To estimate soil erosion by Cs-137 method , at the first, the content of Cs-137 must be determined in various sites of study area and reference profiles, then by the help of mathematical relation between Cs-137 and erosion (Zhang equation), the amount of surface soil erosion can be determined. This research was carried out at the north and South facing of steepy regions under tea cultivated area. The average of surface soil erosion is estimated as 4.84 tons per hectare in year Since the parent materials of the region is granitic, the soil development is weak and soil formation is slow, therefore the erosion must be really controlled. The main reasons of this high level of erosion in these area, incorrect land using due to high slope and bad management of tea orchars. So it is necessary to train the farmer of these regions and show them the scientific and correct manner of tea cultivation.