*3.2.3 Correlation of soil pH, carbon and available P with heavy metal concentrations*

Soil pH was strongly correlated with soil C and available P (**Table 4**). The soils treated with sewage sludge had total metal concentrations in the order Cr > Zn > C u > Pb > Ni > Cd = As. Soil Cr, Zn and Cu strongly correlated with soil pH, while Cd weakly correlated with soil pH. The correlation of pH with As was weak (significant) and negative. There was no correlation of pH with Pb and Ni. Total soil C was strongly correlated with the available P. Soil C was strongly correlated with all the metals except Pb, which was weakly correlated, and As, for which the correlation was not significant. The available P was correlated strongly with Cr, Zn, Cu and Ni, weakly with Pb and not correlated with As and Cd.

*Heavy Metals in Soils Following 50 Years of Sewage Sludge Application DOI: http://dx.doi.org/10.5772/intechopen.110009*


*Soil C = total soil carbon, Avail P = available phosphorus.\* Correlation is significant at p = 0.05 level. \*\*Correlation is significant at p = 0.01 level.*

**Table 4.**

*Correlation coefficients (r) of soil pH, total C and available P with soil-heavy metal concentrations.*
