Abstract: In recent years, social and economic developments in China have caused increasingly serious problems in soil quality in agricultural land affected by heavy metal pollution. However, most soil quality evaluation reports have seldom considered the soil pollution or soil environmental quality issue and largely ignored the effect of soil pollution risk on soil quality evaluation. In this study, we developed a method to introduce soil pollution parameters into the soil quality evaluation system. Taking a typical county-size industrial city as an example, we assessed the soil fertility status based on soil physicochemical properties. We classified the types of risk control of heavy metal pollution in soil in the study area and incorporated the classification into the soil fertility status evaluation system by establishing a piecewise function. Finally, we evaluated the soil quality in agricultural land by our method. The results showed that the coefficient of soil physicochemical property in the study area varied as AP>SEC>TP>SOC>CEC>TN>pH, while soil fertility tended to increase with decreasing terrain and increasing rivers. The high fertility areas were mainly distributed in the plains of the northwest and northeast, whereas low fertility areas, surrounded by fertility transitional areas, were in the southeastern hilly and mountainous areas and the lowland in the west. Classification of the types of risk control of soil pollution in agricultural land showed that, for the 8 heavy metals tested, at least 88.89% samples for Cd and 98.61% for Cr belonged to the priority protection category, and 11.11% samples for Cd and 1.39% for Cr met the safe use standard, indicating heavy metal pollution was dominated by Cd. Soil quality assessment showed that the overall distribution of soil quality was similar to that of soil fertility; however, soil contamination risk evaluation expanded the low-quality soils in the southwestern study area eastwards, resulting in a denser distribution of lower-quality soils in the southeast. The above research results demonstrated that by introducing classification of the soil pollution risk control types, soil fertility correction should generally be reduced, and the spatial distribution of native soil fertility status may also be modified to a certain extent.

Key words: soil fertility, soil pollution risk control, type division, evaluation of soil quality