Table 5.

Regression models and their validation results for metal elements uptake by A. bisporus cultivated on sewage sludge amended casing material.

Metal Element	Model Equation	R 2	ME	RMSE	F	p
Cu	y = 20.217 + (0.067 × pHC) + (1.276 × OCC) − (0.360 × MES+C)	0.9918	0.98	0.375	588.47	<0.001
Cr	y = −2.814 − (0.335 × pHC) − (0.017 × OCC) + (0.593 × MES+C)	0.9900	0.99	0.044	375.89	<0.001
Cd	y = 0.079 − (0.003 × pHC) + (0.006 × OCC) + (0.004 × MES+C)	0.9956	0.99	0.004	833.15	<0.001
Fe	y = −6963.721 + (4.645 × pHC) + (0.313 × OCC) + (2.242 × MES+C)	0.9976	0.98	0.410	1542.49	<0.001
Mn	y = −906.571 − (0.096 × pHC) − (0.237 × OCC) + (2.885 × MES+C)	0.9924	0.98	0.003	479.34	<0.001
Zn	y = −63.503 + (0.058 × pHC) + (0.891 × OCC) + (0.208 × MES+C)	0.9988	0.99	0.002	323.58	<0.001

pH_C: pH of casing material; OC_C: organic carbon of casing material; ME_S+C: metal element concentration in substrate + casing material; ME: model efficiency; RMSE: root mean square error.