In order to confirm the effects of planting types on the vertical distribution of soil organic carbon (SOC)

five typical planting types of terraces in the Baozigou basin located in Gansu province were studied

which included maize

wheat

potato

apple and intercropping (apple+potato). SOC content

storage and the controls were studied to investigate the effects of planting types on the stability of SOC in 0—200 cm soil layer. The results showed that: (1) The content of SOC in 0—200 cm ranged from 3.33~4.86 g/kg

and the differences among different planting types were significant; SOC in intercropping and apple were significantly higher than those in maize and wheat (P<0.05); SOC was significant different in different soil layer

and the content of SOC in 0—20 cm soil layers were significantly higher than other layers and the difference were slightly with the soil depth increased. The storage of SOC ranged from 8.0 t/hm2to 11.69 t/hm2

and the difference was more outstanding among different planting types; specifically

SOC storages in intercropping and apple were significantly higher than those in maize and wheat. (2) The distribution ratio of SOC in 0—20

20—100 and 100—200 cm accounted for 17.57%

41.21%

and 41.22%

respectively. The influences of different planting types on the stability of SOC distribution were small. Among different planting types

the ratio of the SOC storage in 0—20 cm to 20—40 cm soil layer were 1.51~1.78

0—20 cm to 40—60 cm soil layer were 1.78~2.02

which indicates that soil is developing to maturation and soil quality is significantly improved. (3) Moisture has an effect on the vertical distribution of SOC; planting types had certain influences on the distribution and the storage of SOC

the apple orchard of terraced fields in the loess hilly region had a good advantage on the improvement of soil organic carbon in the Loess Plateau.