In order to assess experimentally the quantitative roles in binding the soil, nutrient conservation and retarding water runoff and soil erosion, six herbaceous species dominant on the banks of the River Gomti at Jaunpur (India) were selected. Young seedlings collected from the river bank were sown on sloping experimental plots in the Botanic Garden, Banaras Hindu University. Known quantities of water were sprayed on vegetated and bare plots, and runoff water and soil were collected in separate cemented reservoirs. Using a technique described by Ambasht (1970), the soil conservation value of selected grasses and sedge was found to range from 87·6 to 95·4%, and of dicotyledon wccds from 52·8 to 93·8%. The plants retarded water runoff by about 60%, compared with the bare plot. Ambasht's formula for soil conservation value has been modified to establish water conservation values for
herbaceous cover, compared with the bare plot, and these values ranged from 65 to 74% for grasses and sedge, and 27 to 72% for dicotyledon weeds. The physico chemical properties of the soil of the bare plot, vegetated plots and eroded soils were compared to determine the role of these herbaceous species in maintaining soil quality and fertility.
