Table 7: Effect of sewage sludge and stabilized sewage sludge on the DTPA-extractable copper in relation to soil type, sewage source, mixing rate, and incubation period.

TreatmentsFluvial soilCalcareous soil
SS1SS2SS1SS2
30 day60 day30 day60 day30 day60 day30 day60 day

Mixing rate, 10%

C3.86d3.88d3.86d3.88b3.11d3.10d3.11b3.10a
SS7.01a6.98a6.95a6.90a6.17a4.68a4.39a3.64a
SS + CFA6.70a6.03b6.62ab6.62a4.11c3.19d3.39b3.29a
SS + B6.22b6.85a6.21bc5.98a2.88e3.57cd3.36b2.77a
SS + SBFL6.40ab6.80a6.90ab6.55a3.66c3.88bc4.25a3.62a
SS + CaCO36.99a6.94a6.80ab6.30a3.96c4.35ab4.32a3.36a
SS + WH6.73a5.79b5.88c4.20b3.81c3.33d3.12b3.18a
SS + RS5.27c4.63c6.55ab6.89a3.89c3.36d4.34a3.55a
SS + CS6.69a6.95a6.71ab5.97a4.87b3.33d4.12a3.39a

Mixing rate, 25%

C3.86c3.88e3.86d3.88e3.11d3.10cd3.11c3.10bc
SS7.01ab6.98a6.95ab6.90a6.17a4.68a4.39a3.64a
SS + CFA6.46ab5.18cd5.92c5.53b3.26d2.88d2.63d2.97cd
SS + B5.80ab5.59bcd5.72c5.25bc3.27d3.39bc3.88b2.62d
SS + SBFL6.37ab6.50ab6.89ab6.59a3.52cd3.60b3.78b3.50a
SS + CaCO37.21a7.11a7.28a6.77a4.05bc4.59a4.47a3.44ab
SS + WH6.40ab5.98abc6.00bc4.02de3.54cd2.81d2.75cd2.99cd
SS + RS5.22bc4.59de6.51abc6.64a3.67bcd2.70d3.85b2.74cd
SS + CS6.31ab6.39ab6.12bc4.73cd4.32b3.67b4.19ab2.84cd

Values accompanied by different letters are significantly different within column ( ).