Abstract: The restoration of soil microenvironment is the basis for the restoration of sand land and desertified grassland. However, it is not clear how the improvement measures interact with the soil microenvironment to increase primary productivity of sandy land. Here, we conducted an experiment in a semifixed dune in Xilingol, Inner Mongolia, to examine the impacts of different improvement measures on sandy soil microenvironment. We measured soil physical properties (soil bulk density, aggregates, temperature, moisture) and plant biomass under two treatments: threedimensional measure (crust + water retention agent), comprehensive measure (seeding + crust + water retention agent) and control. Our results showed that both the threedimensional and comprehensive measures improved soil structure (lower soil bulk density and higher water stability of large aggregates), increased soil infiltration and soil water content, but reduced water evaporation. Both ameliorations reduced the average daily temperature in summer, which was beneficial to reduce water evaporation. The three-dimensional measure increased the average daily temperature in early spring, which might promote seed germination, thus improving the utilization rate of snow water. Both measures reduced diurnal temperature variations. The lower daytime temperature was conducive to reducing water evaporation. Compared with the three-dimensional measure, the comprehensive measure increased plant biomass due to sowing treatment, which in turn improved soil microenvironment, and thus obtained a better improvement effect. This study provides empirical evidence for the use of three-dimensional and comprehensive measures for improving the microenvironment and primary productivity of sandy soils.

Key words: crusts, water retaining agent, soil temperature, soil moisture, soil microenvironment.