In order to understand the influence of reclamation on the soil physical and chemical properties of alpine-cold grassland in northwest Sichuan

the method of replacing the time with the space was applied

and the vegetable lands in the alpine grassland which had been reclaimed for three and ten years were chosen as the research objects. In addition

the uncultivated natural grassland was taken as the control group to study the changing characteristics of the physical and chemical properties of 0—60 cm soil layers of different land reclamation years. The results showed that the artificial cultivation led to significant reduction in soil nutrient content

soil physical and chemical properties of natural alpine meadow

and the soil quality further decreased with the increase of reclamation years. After ten years of reclamation

soil bulk density and sand content in the 0—60 cm soil layer were increased by 21.1% and 8.0%

respectively; soil moisture

organic matter

total nitrogen

available nitrogen

and clay contents were decreased by 38.4%

44.1%

39%

47.1%

and 19.2% respectively. Soil physical and chemical properties

and soil carbon and nitrogen contents were decreased most significantly in the surface layer (0—20 cm). With increasing soil depth

soil physical and chemical properties were weakened. The losses of soil carbon and nitrogen in the 0—20 cm soil layer occurred in the first three years of reclamation

while soil carbon and nitrogen in deeper layers (20—40 cm

and 40—60 cm) were not significantly lost in first three years of the reclamation. Losses of soil carbon and nitrogen mainly occurred in the first three to ten years of reclamation.