Table 1.

Soil characteristics

Soil (characteristic)Treatment (ha−1yr−1)No. (107) of bacteria and archaea (g of soil [dry wt]−1)% Organic CpHHeavy-metal content (mg kg of soil [dry wt]−1)a
CdCuNiZn
Control180 kg of N260 ± 100.887.10.412956
A (low sludge-low metal)100 m3 of sludge240 ± 91.076.80.62111102
B (low sludge-high metal)100 m3 of sludge284 ± 121.106.90.84316163
C (high sludge-low metal)300 m3 of sludge297 ± 121.485.51.13716216
D (high sludge-high metal)300 m3 of sludge200 ± 91.515.32.79432359
  • a Aqua regia digest (25).