Abstract

An investigation was carried out during June, 1991 May, 1992 at the Horticultural Research Station, Kodaikanal to study the effect of rainfall, stream flow and vegetation on soil erosion and run off. The natural forest shola enjoying different types of vegetational cover without any soil conservation measure was compared with cultivated banana watershed having contour stone wall as soil conservation measure. The sediment lost through soil erosion and run off and the nutrient lost from the surface soils of the above watersheds were quantified at monthly intervals. The results revealed that the monthly average rainfall more or less ramained the same in both the watersheds with the highest rainfall during October. The data on sediment loss indicated that the forest shola watershed had a higher rate (600 kg/ha/year) of soil erosion than the banana watershed (504 kg/ha/year). The cumulative water lost through run off was higher (121 mm) in shola than the banana watershed (91 mm). The sedimentation and run off reached their peak in the month of October in both the watersheds. The loss of major nutrients also followed a similar pattern as that of the run off water but the levels of loss of N and K were relatively higher than that of P. The differential soil and nutrient loss through run off water was attributed to the initial soil properties, soil conservation measures and topography of the watersheds.

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