Abstract: 【Objective】 It is necessary to assess the evolution of heavy metals in soils under long-term fertilization and cropping, which helps rational fertilization and healthy soils in the area.【Method】At a long-term Black Soil experimental station, Jilin, China, six treatments were selected in this study, including CK (control without fertilization), N (nitrogen), NP (nitrogen + phosphorus), NPK (nitrogen + phosphorus + potassium), NPKM (nitrogen + phosphorus + potassium + manure), and 1.5NPKM (1.5 times of NPKM). The soil in a 0-20 cm layer in each plot for each treatment was sampled in 1989, 1994, 2000, 2006, 2010, and 2012, respectively, and the total/available metal content (Cu, Zn, Pb, and Cd) was measured. Additionally, the metal activity index was also calculated. 【Result】 The results showed that the total and available metals (Cu, Zn, Pb, and Cd) did not change with the fertilization year in CK and those treatments receiving chemical fertilizers; except Pb significantly increased under manure application (NPKM and 1.5NPKM). However, Cd activity index decreased markedly by 27%-28% for manure treatments. Three stages in the evolution of soil metals with long-term manure application, attributed to the stage-by-stage change in the metal content of animal manure, were presented, that is, there was a slow increase between 1989 and 2000, a rapid increase between 2000 and 2010, and it kept steady or slowly decreased after 2010. For example, 0.03 mg·kg^-1·a^-1, 0.07 mg·kg^-1·a^-1, and -0.13 mg·kg^-1·a^-1, respectively, for total soil Cd in 1.5NPKM, and 0.11 mg·kg^-1·a^-1, 0.53 mg·kg^-1·a^-1, and -1.25 mg·kg^-1·a^-1, respectively, for available soil Cu in NPKM, were assessed in the three stages above mentioned. Further, a partial correlation analysis showed that the activity index of Cu, Zn, and Pb was positively related to Olsen-P, SOM, and negatively related to soil pH, respectively; whereas the Cd activity index was negatively related to Olsen-P and SOM and positively related to soil pH, which suggested a more complex response for Cd to soil properties influenced by long-term fertilization. 【Conclusion】 Chemical fertilizers did not have an effect, but organic fertilizers strongly influenced the evolution of heavy metals in black soil, where three stages (slow increase, rapid increase, and slow decrease) were observed. Thus, it is critical to both apply organic fertilizers and pay attention to their potential risk for sustained crop production. There is still a risk of long-term cattle manure application with 30 t·hm^-2 to the black soil.

Key words: black soil, long-term fertilization, heavy metal, activity index, manure