Table 2.

Effects of laboratory Cu contamination and oxytetracycline and captan (O+C) contamination on the respiration rate of unpolluted (UP) and chronically zinc-polluted (P) soils

Soil kind	Cu treatment mg kg−1 dw	O+C treatment	Respiration rate mmol CO2 kg−1 OM 24 h−1			% of control
			X	SD	V
UP	0	No	89.23	0.71	0.01	100
	500	No	84.23	1.41	0.02	94
	1,500	No	78.29	2.18	0.03	88
	4,500	No	64.33	2.82	0.04	72
	0	Yes	51.94	0.69	0.01	58
	500	Yes	46.96	0.11	0.00	53
	1,500	Yes	41.99	0.69	0.02	47
	4,500	Yes	37.13	0.95	0.03	42
P	0	No	109.45	9.11	0.08	100
	500	No	96.67	3.34	0.03	88
	1,500	No	80.77	0.57	0.01	74
	4,500	No	67.80	0.16	0.00	62
	0	Yes	63.43	4.11	0.06	58
	500	Yes	55.20	1.83	0.03	50
	1,500	Yes	43.34	3.24	0.07	40
	4,500	Yes	31.05	1.38	0.04	28

Values are means (X) with standard deviation (SD) and variance coefficient (V) (n = 2)

Respiration rates of control samples of P and UP soil (not contaminated in laboratory with copper nor oxytetracycline/captan) are given in bold