Different soil and water conservation practices often varied considerably in sediment interceptionand runoff reduction.The cost effectiveness of sediment control can be quantified by the ratio of detainedrunoff and sediment(Rrs).Perennially monitoring data were collected from three typical loess regions(Xifengand Tianshui City in Gansu Province

Suide City in Shaanxi Province)and Rrs were calculated for differenttillage and biological practices.The results showed that the Rrsvaried greatly from 8.5to 36.4m3/t.Fortillage management

contour tillage showed the highest Rrs

followed by level ditch tillage and shallow plowing

while deep plowing had the lowest.For biological managements

the Rrsof intercropping of low-stemand high-stem crops was higher than those of monoculture of low crops and rotation of middle high-stemcrops.The Rrsof pasture(sweet clover

alfalfa)rotation was significantly higher than crop rotation

andsweet clover/crop rotation system was better than alfalfa-crop rotation system in terms of erosion control.With increasing rainfall and slope gradient

Rrsvalues decreased in general.The practice with higher Rrscouldreduce more runoff discharge and increase soil moisture content with similar performance in sediment control.