Background Expressway construction will temporarily occupy and destroy part of the land, and bring damage to land resources, such as soil erosion and other resources and environmental problems. Compared with natural soil, the soil quality of temporary used land becomes worse; moreover, only basic physical and chemical properties are considered in the restoration, and neither the enzyme activity index, nor the correlation among affecting factors. Thus ecological restoration and reclamation of those temporary lands are not so effective.

Methods In order to effectively reclaim and ecologically restore the temporary land damaged by Jianglou expressway engineering construction in Guangdong Province, the T test and Principal Component Analysis (PCA) via SPSS 17.0 SAS 9.0 software were used to study the changes of soil quality in 5 kinds of temporary used land, such as pioneer road, mixing station, construction camp, spoil ground and borrow pit, as well as the difference of soil quality among 5 temporary lands.

Results 1) The soil organic matter, total nitrogen (N), available N, phosphorus (P) and enzyme activities (soil invertase, urease, acid phosphatase, and catalase) in the soil from borrow pit were the lowest, and the soil acidification was also the most severe. 2) The soil damaged by construction camp had the highest organic matter, total N, available N and P. 3) The highest soil bulk density and compaction, the porosity and field capacity in the soil from the mixing station were the lowest. 4) The spoil ground soil had the lowest soil bulk density and minimum compaction, lower organic matter content, total N, available N and P, but the highest available K. 5) The higher level of soil organic matter content and other nutrient content was found in the soil from pioneer road, while soil bulk density and soil porosity, moisture content and field capacity were lower in this soil (P < 0.05). The differences in the soil quality among the soils affected by different use of highway temporary construction were extremely significant (P < 0.001).

Conclusions Lack of organic matter, total N, available N, P content and the decrease of enzyme activities are the major limiting factors for land reclaim and ecological restoration of soils from borrow pit and spoil ground. The increased compaction and soil bulk density, and decreased porosity and field capacity are the major limiting factors for the land reclaim and ecological restoration of soils from construction camp, mixing station and pioneer road. PCA reveals that the comprehensive quality of soils from borrow pit and spoil ground is significantly different from that of soils from the other three sites. Targeted measures for soil improvement should be taken to temporary land. PCA is a robust tool to distinguish the properties of soils under different temporary construction land and to explore the key factors of soil amelioration. The study provides a theoretical basis for reclaim, ecological restoration and soil erosion control in land damaged by engineering.