Table 2.

Effect of treatments on properties of the Luddington soila

Treatment%C%NpHMoisture content (%)C-mic (μg g−1)Respiration (μg of C g−1 day−1)TdR incorporation (10−13 mol ml−1 h−1)Clover yield (g)Principal-components analysis
PC1PC2
Uncontaminated sludge2.000.165.17.90117.71.78 (1.04)2.63 (2.04)2.720.166−0.230
No sludge1.520.135.49.76116.91.48 (1.46)2.60 (2.58)1.64*−0.021−0.038*
Low Cu2.440.215.210.48*99.01.44 (1.70)1.07* (1.28)2.22−0.028−0.008*
High Cu2.64*0.23*5.414.15*55.4*0.74* (2.42)0.34* (1.68)1.50*−0.587*−0.027*
Low Zn2.250.165.47.94124.21.71 (0.98)3.03 (2.39)3.06−0.1550.063*
High Zn1.970.155.510.32*90.81.96 (2.16)1.72 (1.88)1.68*0.0330.051*
Low Ni2.540.195.38.6981.81.48 (1.04)2.64 (2.30)2.590.1600.138*
High Ni1.730.135.49.2585.01.34 (1.12)3.17 (2.99)2.020.1210.117*
Mean SE0.190.020.110.8219.50.19 (0.37)0.42 (0.49)0.330.0880.042
  • a Asterisks indicate significant difference from the uncontaminated sludge treatment (n= 4, P < 0.05, mean SE from ANOVA). For the respiration and TdR data, values are given after adjusting for covariance of the moisture content in the ANOVA, and the unadjusted values are given in parentheses.