The alfalfa mean biomasses in different treatments varied from 0.56 to 2.23 g/pot in root dry weight and from 1.80 to 4.88 g/pot in shoot dry weight (Table 3). When PAHs- degrading bacteria were inoculated into the soil, there was a large difference in whole plant biomasses systematically observed between inoculated and uninoculated soils; for example, root and shoot dry weight increased significantly by 297% and 136% (p < 0.05). Against our expectation, the biomass of alfalfa decreased to a greater extent with increasing doses of sewage sludge (SS) and cattle manure (CM) compared with that of CK3. However, there was no significant difference between SS1 and SS3 in plant biomass, with the exception of SS1 in root biomass. In contrast, the dosage effect of CM was more apparent; the shoot was stimulated by low and medium dose (CM1 and CM2) and significantly inhibited by high dose (CM3). The total biomass in the treatment with low dose CM, CM1 accumulated to 6.67 g/pot, which was 2.8 times higher than that of CK2, but decreased sharply to 3.79 g/pot at the 2% addition level.