The LC50 of the pH-adjusted soils increased more than the LC50 of the nonadjusted soils ( Table 4), especially after the first 90 d of incubation. For example, the LC50 of the pH-adjusted K and K6K soils after 184 d of incubation was 264 and 312 ng 100 μl−1 of soil suspension, respectively, whereas the LC50 of the unadjusted soils was 63 and 69 ng 100 μl−1, respectively, after 195 d ( Table 4). The variability in toxicity of the pH-adjusted soils was also greater, especially after the first 90 d, as indicated by the large CI. The pH of the CaCO3-amended soils remained above pH 7.0 (average pH of 7.32) throughout the incubation.