To control the soil and water losses is one of the general objectives of the Cropland Conversion Program (CCP). Therefore

there is a growing need to assess and improve the feasibility of soil and water conservation between cropland and conversion options in semiarid hilly loess plateau during the long-term period. The experiment was comparatively investigated upon runoff and soil erosion rate of conversion options under natural rainfall. The data were collected on nine runoff plots of 50 m~2 and six 100 m~2 plots over a period of 14-year. Significant differences occur between the conversion options in assessment of the water and soil conservation effects and efficiencies. On the basis of runoff during 14 years

the following ranking from the most to the least favorable was made for water and soil conservation effects: shrubland > wild grassland > woodland > pastureland. The runoff reduction mainly occur in July and August. The percentage of reduction runoff in July and August versus total reduction runoff in pastureland

shrubland

woodland and wild grassland is 49%

73%

58% and 73%

respectively

that of reduction erosion is 75%. The reduction ratio of cumulative runoff in woodland and pastureland gradually decreased from 43%

52% during 1~2-year

30% during 8 years and to 12%

21% during the 14 years

respectively. Inversely

those in shrubland and wild grassland increased from 43%

41% during 1~2 year

61%

59% during 8 years and to 66%

44% during the 14 years. It may be concluded that theuse of purple alfalfa (Medicago sativa) and Chinese pine (Pinus tabulaeformis)

in some cases

can produce much better conservation results such as in the short-term other than in the longer term.