Table 4.

Effects of ambient CO₂ concentration (400 μmol mol⁻¹) and elevated CO₂ concentration (800 μmol mol⁻¹) treatments on soil nutrients after being used for soybean cultivation. The asterisk indicates a significant difference between ambient and elevated CO₂ treatments (P < 0.05). Data are mean ± S.D. (n = 5 or 6). O.M., organic matter; Hy.N, available nitrogen; A.P, available phosphorus; A.K, available potassium.

Mineral element	Content (g/kg)		Mineral element	Content (mg/kg)
	Ambient	Elevated		Ambient	Elevated
Ca	7.02 ± 0.32	6.94 ± 0.28	Mn	685.00 ± 18.71	703.33 ± 12.11
K	9.31 ± 0.24	9.24 ± 0.23	Cu	85.33 ± 3.26	87.08 ± 4.22
Mg	4.43 ± 0.11	4.50 ± 0.08	Zn	97.52 ± 3.99	99.17 ± 2.28
Fe	53.59 ± 1.16	55.40 ± 3.60	B	54.23 ± 4.70	48.24 ± 2.37*
Al	56.26 ± 2.04	57.65 ± 2.50	Na	1.32 ± 0.04	1.31 ± 0.04
C	155.25 ± 7.64	153.84 ± 6.90	S	491.67 ± 19.41	480.00 ± 17.89
N	8.52 ± 0.29	8.39 ± 0.53	Hy.N	720.50 ± 15.29	706.17 ± 6.43
P	1.00 ± 0.01	0.99 ± 0.02	A.P	12.48 ± 1.88	13.67 ± 1.20
O.M.	344.12 ± 9.29	341.97 ± 18.00	A.K	338.00 ± 74.47	254.8 ± 13.85*