Assessment of Copper and Zinc in Soils of a Vineyard Region in the State of São Paulo, Brazil

Table 2

Regression coefficients for the available forms of Cu and Zn extracted by DTPA and CaCl₂; natural (independent variable) and acidified (dependent variable) samples.

Element/method	𝑟^2	Intercept			𝑃	Angular coefficient			𝑃
		Min.	Average	Max.		Min.	Average	Max.
CuDTPA	0.95	−0.61	−0.18	0.24	0.39	1.29	1.37	1.44	<0.01
ZnDTPA	0.94	−0.88	−0.17	0.53	0.62	1.06	1.13	1.20	<0.01
CuCaCl	0,15	0.028	0.033	0.038	<0.01	0.053	0.126	0.200	<0.01
ZnCaCl	0.59	0.401	0.611	0.820	<0.01	0.480	0.605	0.730	<0.01