. 2021 Jul 14;11:14489. doi: 10.1038/s41598-021-93805-5

Table 2.

Growth of Zelkova serrata seedlings applied with four levels of wood ash (WA; 0, 5, 10, and 20 Mg ha⁻¹) and two levels of N fertilizer (N fert; 0 and 150 kg ha⁻¹) across three different soil types (LS, landfill saline soil; FI, forest infertile soil; FA, forest acidic soil) at the end of this study (20 weeks after treatment).

Soil	N fert (kg ha⁻¹)	Wood ash (Mg ha⁻¹)	Height (cm)	RCD (mm)	Leaf area (cm² tree⁻¹)	SLA (cm² g⁻¹)
LS	0	0	117 (8)^a	9.6 (0.5)^a	53 (6)^c	65 (6)^a
		5	98 (10)^a	9.7 (0.5)^a	63 (3)^bc	67 (6)^a
		10	112 (14)^a	11.6 (1.6)^a	59 (6)^bc	68 (7)^a
		20	108 (8)^a	8.2 (0.5)^a	45 (9)^c	62 (10)^a
	150	0	121 (8)^a	10.2 (0.9)^a	93 (3)^abc	76 (1)^a
		5	129 (6)^a	10.8 (0.5)^a	103 (20)^ab	75 (7)^a
		10	139 (3)^a	12.1 (1.0)^a	130 (14)^a	90 (1)^a
		20	117 (15)^a	9.2 (0.7)^a	63 (13)^bc	70 (8)^a
		p values
		WA	0.67	0.02	0.01	0.35
		N	0.01	0.27	< 0.0001	0.01
		WA * N	0.30	0.97	0.14	0.75
FI	0	0	84 (7)^bcd	8.0 (0.3)^d	35 (4)^c	54 (3)^a
		5	117 (15)^abcd	8.5 (0.6)^cd	51 (8)^bc	59 (4)^a
		10	87 (2)^cd	8.6 (0.3)^d	39 (4)^c	52 (4)^a
		20	84 (4)^c	8.2 (0.5)^d	38 (5)^c	56 (4)^a
	150	0	130 (11)^ab	11.9 (1.2)^ab	136 (25)^a	68 (4)^a
		5	123 (11)^abc	13.2 (0.6)^a	112 (11)^a	70 (4)^a
		10	146 (11)^a	12.3 (0.4)^ab	120 (18)^ab	68 (8)^a
		20	135 (8)^a	10.8 (0.8)^bc	79 (17)^abc	69 (9)^a
		p values
		WA	0.41	0.02	0.13	0.93
		N	< 0.0001	< 0.0001	< 0.0001	0.002
		WA * N	0.04	0.45	0.37	0.96
FA	0	0	135 (8)^a	12.3 (0.3)^a	117 (8)^bc	78 (6)^a
		5	118 (6)^a	15.3 (0.9)^a	172 (13)^abc	72 (4)^a
		10	127 (7)^a	13.4 (0.6)^a	148 (21)^abc	67 (4)^a
		20	120 (10)^a	15.7 (1.9)^a	141 (11)^abc	57 (9)^a
	150	0	142 (8)^a	12.2 (0.7)^a	94 (11)^c	55 (5)^a
		5	129 (3)^a	14.3 (0.7)^a	213 (31)^a	67 (8)^a
		10	139 (8)^a	14.0 (1.2)^a	164 (27)^abc	62 (11)^a
		20	142 (12)^a	13.7 (0.9)^a	195 (16)^ab	86 (6)^a
		p values
		WA	0.37	0.01	0.0008	0.75
		N	0.03	0.56	0.11	0.76
		WA * N	0.85	0.79	0.21	0.01

RCD, root collar diameter; SLA, specific leaf area.

Standard errors are shown in parentheses (n = 5). P values are from the result of two-way ANCOVA with initial RCD of seedlings as the covariate to detect the effect of wood ash and N fertilizer on height, RCD, leaf area, and SLA within each soil type. Significant p values are in bold. Different lower case letters within each soil indicate significant differences (p < 0.05, Tukey–Kramer comparison lines for least squares means) in each growth property across four wood ash levels and N fertilizer treatment.