Taking the slope-farmland of purple soil in Hechuan

Chongqing and Chuxiong

Yunnan as samples

the study analyzed the soil water storage

soil stability and tilth characteristics based on field survey and lab tests. The results showed that: (1) Soil infiltration rate decreased with the increasing depth of cultivated-layer of purple soil in slope-farmland

and the soil stable infiltration rate of the 0—20 cm

20—40 cm

40—60 cm cultivated layer was 5.80 to 9.58 mm/min

2.81 to 4.35mm/min

and 0.98 to 1.96mm/min

respectively. The maximum effective water storage capacity of soil was 49.93 to 66.26

46.04 to 59.05

and 37.42 to 43.55 mm at corresponding soil depth. (2) Soil stability of cultivated-layer was significantly different among purple soil farmlands. The＞5 mm

5 to 3 mm

and 3 to 0.5 mm fractions were dominant soil aggregate structure

and the content of ＞0.25 mm fraction of water stable aggregates decreased with increasing cultivated-layer depth significantly. Soil stability index of the 0—20 cm cultivated-layer varied and followed the order of high-yield tobacco cultivated-layer (2.96)＞high-yield maize cultivated-layer (2.55)＞low-yield tobacco cultivated-layer (2.45)＞low-yield maize cultivated-layer (2.38). Compared with that of the 0—20 cm soil layer

the stability index of the 20—40 cm and 40—60 cm layer of maize and tobacco decreased by 0.44

0.64 and 0.66

0.71

respectively. (3) The soil shear strength and the penetration resistance of cultivated-layer on different slope-farmland was significantly different (p＜0.05)

and the soil shear strength was in the order of low-yield maize cultivated-layer (36 kPa)＞high-yield maize cultivated-layer (29 kPa)＞low-yield tobacco cultivated-layer (25 kPa)＞high-yield tobacco cultivated-layer (21 kPa)

with the peaking value appearing in the 20—40 cm layer. Soil penetration resistance of high- and low-yield cultivated-layer was 0.3 to 1.9 Mpa and 0.5 to 2.5 MPa

with the peaking value appearing in the 40 to 50 cm layer. The high-yield cultivated-layer of purple soil slope-farmland presented high stable infiltration rate

large storage capacity

strong soil water holding capacity

high soil structure stability

low soil anti-shear strength and penetration resistance.