Table 4.

Stepwise multiple regressions between soil extractable metals and soil properties (including soil total metals).

Extractant		Regres. steps	Cu	r2	Zn	r2	Pb	r2	Cd	r2	Fe	r2	Mn	r2
DTPA	R	1	TCu	0.916***	TZn	0.664***	TPb	0.850***	TCd	0.761***	− pH	0.500***	− pH	0.313**
		2	− pH	0.930***	Ap	0.708***	TP	0.911***					TMn	0.473***
	W	1	TCu	0.950***	TZn	0.726***	TPb	0.836***	TCd	0.801***	− pH	0.642***	ns
		2	SOM	0.977***			SOM	0.896***	− pH	0.848***
	P	1	TCu	0.884***	TZn	0.680***	TPb	0.826***	TCd	0.929***	− pH	0.591***	ns
		2	− TP	0.941***	− pH	0.748***	− pH	0.873***	− TP	0.970***
EDTA	R	1	TCu	0.921***	TZn	0.712***	TPb	0.887***	TCd	0.826***	TN	0.239**	TMn	0.540***
		2	TN	0.948***	TN	0.763***	TP	0.911***					TP	0.675***
	W	1	TCu	0.952***	TZn	0.803***	TPb	0.810***	TCd	0.848***	ns		TMn	0.910***
		2	SOM	0.980***			− pH	0.893***
	P	1	TCu	0.925***	TZn	0.781***	TPb	0.928***	TCd	0.953***	ns		TMn	0.644***
		2	TN	0.956***	TN	0.841***	AK	0.953***	TP	0.975***			TP	0.754***
HCl	R	1	TCu	0.941***	TZn	0.746***	TPb	0.663***	TCd	0.801***	TFe	0.145*	TMn	0.439**
		2			Ap	0.789	Ap	0.769					TN	0.520**
	W	1	TCu	0.960***	TZn	0.846***	TPb	0.825***	TCd	0.863***	− pH	0.289**	TMn	0.760***
		2	SOM	0.979***			SOM	0.872***					− pH	0.816***
	P	1	TCu	0.853***	TZn	0.837***	TPb	0.584***	TCd	0.962***	Ap	0.453***	TMn	0.744***
		2	TP	0.947***	TN	0.890***	TP	0.860***	TP	0.985***			TP	0.819***
NH4OAC	R	1	TCu	0.665***	TZn	0.166*	TPb	0.270**	TCd	0.392***			− pH	0.414***
		2			− pH	0.403***	− pH	0.631***	− pH	0.577***			− Ap	0.539***
	W	1	TCu	0.879***	ns		TPb	0.281**	TCd	0.235**			− pH	0.551***
		2					− pH	0.611***	− pH	0.554***			TMn	0.755***
	P	1	TCu	0.655***	TZn	0.250*	− pH	0.454**	TCd	0.681***			− Ap	0.488**
		2	− pH	0.785***	− TP	0.538**	TPb	0.802***	− pH	0.920***
NH4NO3	R	1	TCu	0.190*	− pH	0.557***	− pH	0.573***	− pH	0.396**			− pH	0.498***
		2	− pH	0.370**	TZn	0.739***	TPb	0.64***	TCd	0.680***			− Ap	0.602***
	W	1	TCu	0.413***	− pH	0.734***	− pH	0.748***	− pH	0.644***			− pH	0.714***
		2			TZn	0.894***	TPb	0.848***	TCd	0.865***			TMn	0.855***
	P	1	TCu	0.428**	− pH	0.790***	− pH	0.842***	− pH	0.377**			− pH	0.636***
		2			TZn	0.879***	TPb	0.916***	TCd	0.77***			TMn	0.754***

TCu total Cu, TZn total Zn, TPb total Pb, TCd total Cd, TFe total Fe, TMn total Mn.

***, ** and * indicate significant correlations at the probability level of p < 0.001, p < 0.01 and p < 0.05, respectively, ns not significant.