Soil physical properties change in the process of oasisization

Oasisization is a process of converting a natural desert into a man-made oasis in order to satisfy social needs under certain economical and technical conditions.This paper substitutes space for time in order to study physical property changes of oasis soil along the oasisization in about a 1,000-year period.This research focuses on providing the bases for better understanding the process of oasisization.The results show:(1)In about 1,000-year chronological scale,the bulk density and the saturated soil hydraulic conductivity of the surface layer(0-20 cm)significantly reduced with the increase of land reclamation time,while soil porosity,stability of aggregates,and silt content significantly increased.The soil bulk density of the unreclaimed filed(0 year)and the reclaimed field(about 1,000 years)in the surface layer(0-20 cm)are 1.51 g/cm3 and 1.35 g/cm3,the total porosity are 43.16%and 49.27%,the capillary porosity are 38.73% and 47.10%,the water-stable aggregate(>0.25 mm)content are 24.60% and49.59%,the sand content are 85.42% and 61.56%,the clay content are 3.93% and 4.80%,the specific surface area are 128 cm2/g and 231 cm2/g,and the saturated hydraulic conductivity are 0.74 cm/h and 0.34 cm/h,respectively.(2)In the first 30 years of the oasis reclamation,the changes are relatively fast,and the rates of the saturated soil hydraulic conductivity,dry aggregate(>0.25yr,respectively.