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

Table 1.

Soil chemical properties applied with four levels of wood ash (WA; 0, 50, 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)	pH	Organic matter (%)	Total N (g kg⁻¹)	Available P (mg kg⁻¹)	CEC (cmolc kg⁻¹)
LS	0	0	8.7 (0.0)^b	0.83 (0.03)^b	0.21 (0.01)^a	46.8 (1.0)^c	15.8 (0.1)^a
		5	9.1 (0.1)^a	0.97 (0.00)^b	0.23 (0.01)^a	57.7 (1.9)^bc	13.6 (0.4)^a
		10	9.2 (0.1)^a	1.37 (0.21)^ab	0.21 (0.02)^a	64.6 (1.1)^b	15.3 (3.1)^a
		20	9.3 (0.1)^a	1.97 (0.34)^a	0.22 (0.00)^a	112.0 NA^a	12.4 (0.0)^a
	150	0	8.7 (0.1)^b	0.81 (0.01)^b	0.24 (0.01)^a	46.6 (0.8)^c	14.6 (0.9)^a
		5	9.0 (0.0)^ab	0.97 (0.06)^b	0.24 (0.03)^a	55.8 (1.1)^bc	12.7 (0.9)^a
		10	9.2 (0.1)^a	1.16 (0.14)^ab	0.23 (0.02)^a	66.4 (3.6)^b	13.6 (0.2)^a
		20	9.2 (0.1)^a	1.45 (0.07)^ab	0.22 (0.01)^a	108.5 (2.5)^a	14.8 (2.5)^a
		p values
		WA	0.0001	0.002	0.82	< 0.0001	0.55
		N	0.25	0.12	0.16	0.54	0.76
		WA * N	0.64	0.35	0.76	0.64	0.54
FI	0	0	7.6 (0.2)^b	0.33 (0.01)^d	0.07 (0.01)^a	17.4 (0.4)^c	9.3 (0.5)^a
		5	8.5 (0.0)^a	0.44 (0.00)^cd	0.08 (0.02)^a	34.6 (0.8)^bc	8.7 (0.4)^a
		10	8.7 (0.1)^a	0.76 (0.04)^b	0.09 (0.00)^a	53.1 (1.0)^b	8.2 (0.6)^a
		20	8.8 (0.0)^a	1.04 (0.09)^a	0.10 (0.02)^a	88.8 (5.6)^a	7.4 (0.2)^a
	150	0	7.4 (0.1)^b	0.34 (0.03)^d	0.09 (0.02)^a	22.9 (6.9)^c	9.1 (0.2)^a
		5	8.5 (0.1)^a	0.48 (0.00)^cd	0.09 (0.02)^a	35.0 (1.4)^bc	8.9 (1.4)^a
		10	8.7 (0.0)^a	0.68 (0.02)^bc	0.09 (0.01)^a	54.7 (4.0)^b	8.7 (0.7)^a
		20	9.0 (0.0)^a	1.10 (0.07)^a	0.09 (0.01)^a	91.5 (3.9)^a	8.7 (1.1)^a
		p values
		WA	< 0.0001	< 0.0001	0.62	< 0.0001	0.49
		N	0.94	0.84	0.67	0.37	0.42
		WA * N	0.29	0.45	0.73	0.91	0.77
FA	0	0	4.9 (0.1)^d	3.29 (0.01)^a	0.83 (0.05)^a	4.1 (0.9)^c	8.7 (0.3)^b
		5	6.4 (0.1)^c	3.19 (0.07)^a	0.72 (0.02)^ab	7.3 (0.6)^c	7.9 (0.0)^b
		10	7.6 (0.0)^b	3.00 (0.06)^a	0.50 (0.04)^b	16.6 (2.2)^b	6.8 (0.7)^b
		20	8.2 (0.1)^a	3.08 (0.14)^a	0.50 (0.02)^b	27.4 NA^a	14.7 (0.7)
	150	0	4.6 (0.1)^d	3.24 (0.04)^a	0.91 (0.10)^a	3.9 (0.1)^c	9.4 (0.1)^b
		5	6.2 (0.1)^c	3.22 (0.08)^a	0.74 (0.07)^ab	7.9 (0.6)^c	8.3 (0.6)^b
		10	7.8 (0.0)^b	2.95 (0.04)^a	0.64 (0.08)^ab	17.0 (1.3)^b	7.6 (0.1)^b
		20	8.2 (0.0)^a	3.20 (0.00)^a	0.61 (0.05)^ab	28.3 (1.6)^a	15.0 (1.8)^a
		p values
		WA	< 0.0001	0.01	0.002	< 0.0001	< 0.0001
		N	0.09	0.78	0.06	0.66	0.37
		WA * N	0.01	0.54	0.78	0.98	0.98

Soil	N fert (kg ha⁻¹)	Wood ash (Mg ha⁻¹)	Exchangeable cations				EC (dS m⁻¹)	NaCl (%)
Soil	N fert (kg ha⁻¹)	Wood ash (Mg ha⁻¹)	K⁺ (cmolc kg⁻¹)	Na⁺ (cmolc kg⁻¹)	Ca²⁺ (cmolc kg⁻¹)	Mg²⁺ (cmolc kg⁻¹)	EC (dS m⁻¹)	NaCl (%)
LS	0	0	0.95 (0.05)^d	3.18 (0.08)^a	2.91 (0.19)^cd	5.09 (0.23)^a	0.69 (0.03)^b	0.022 (0.002)^a
		5	1.47 (0.04)^cd	2.82 (0.44)^a	6.86 (0.78)^bc	5.04 (0.02)^a	1.01 (0.06)^ab	0.021 (0.002)^a
		10	2.21 (0.29)^bc	2.28 (0.52)^a	8.52 (0.20)^ab	4.74 (0.26)^ab	1.08 (0.15)^ab	0.024 (0.003)^a
		20	3.79 (0.32)^a	2.20 (0.08)^a	11.12 (0.14)^a	3.50 (0.00)^c	1.12 (0.01)^a	0.023 (0.001)^a
	150	0	0.98 (0.07)^d	2.90 (0.03)^a	2.77 (0.19)^d	5.23 (0.10)^a	0.75 (0.09)^ab	0.025 (0.003)^a
		5	1.43 (0.12)^cd	1.89 (0.25)^a	7.49 (0.53)^ab	4.80 (0.04)^a	0.85 (0.02)^ab	0.019 (0.001)^a
		10	1.77 (0.06)^cd	2.26 (0.12)^a	9.90 (0.87)^ab	4.62 (0.29)^ab	1.04 (0.00)^ab	0.023 (0.001)^a
		20	3.11 (0.15)^ab	1.92 (0.29)^a	11.46 (1.59)^a	3.87 (0.04)^bc	1.00 (0.09)^ab	0.018 (0.001)^a
		p values
		WA	< 0.0001	0.04	< 0.0001	< 0.0001	0.004	0.15
		N	0.046	0.09	0.32	0.75	0.25	0.32
		WA * N	0.20	0.46	0.77	0.32	0.47	0.18
FI	0	0	0.14 (0.01)^d	0.12 (0.01)^a	4.39 (0.46)^d	0.64 (0.03)^d	0.22 (0.00)^c	0.014 (0.001)^a
		5	0.34 (0.01)^cd	0.11 (0.00)^a	7.31 (0.27)^bcd	0.62 (0.01)^d	0.38 (0.01)^abc	0.017 (0.000)^a
		10	0.75 (0.04)^b	0.12 (0.01)^a	9.91 (0.58)^ab	0.80 (0.01)^cd	0.40 (0.01)^ab	0.017 (0.000)^a
		20	1.62 (0.14)^a	0.13 (0.01)^a	11.75 (0.14)^a	1.03 (0.01)^ab	0.53 (0.08)^a	0.018 (0.002)^a
	150	0	0.16 (0.02)^d	0.12 (0.01)^a	4.82 (0.41)^cd	0.79 (0.02)^cd	0.23 (0.05)^bc	0.015 (0.000)^a
		5	0.43 (0.02)^bcd	0.12 (0.00)^a	7.88 (0.46)^bc	0.63 (0.00)^d	0.38 (0.01)^abc	0.015 (0.002)^a
		10	0.63 (0.04)^bc	0.15 (0.01)^a	11.47 (1.43)^a	0.90 (0.09)^bc	0.43 (0.01)^a	0.018 (0.000)^a
		20	1.53 (0.10)^a	0.16 (0.02)^a	12.46 (0.25)^a	1.10 (0.03)^a	0.54 (0.01)^a	0.017 (0.001)^a
		p values
		WA	< 0.0001	0.049	< 0.0001	< 0.0001	< 0.0001	0.06
		N	0.59	0.03	0.10	0.007	0.62	0.72
		WA * N	0.39	0.33	0.80	0.28	0.96	0.37
FA	0	0	0.19 (0.03)^d	0.23 (0.01)^ab	1.10 (0.25)^d	0.23 (0.02)^bc	0.27 (0.01)^ab	0.016 (0.001)^a
		5	0.98 (0.09)^cd	0.24 (0.00)^a	5.39 (0.02)^c	0.41 (0.01)^ab	0.46 (0.13)^a	0.016 (0.000)^a
		10	1.57 (0.01)^bc	0.22 (0.01)^ab	8.49 (0.67)^b	0.26 (0.02)^abc	0.63 (0.00)^ab	0.018 (0.001)^a
		20	3.01 (0.25)^a	0.22 (0.01)^ab	13.77 (0.73)^a	0.48 (0.11)^a	0.86 (0.02)^a	0.018 (0.002)^a
	150	0	0.15 (0.01)^d	0.19 (0.01)^b	0.77 (0.02)^d	0.18 (0.01)^c	0.60 (0.03)^c	0.014 (0.000)^a
		5	0.97 (0.16)^cd	0.24 (0.00)^a	4.79 (0.30)^c	0.42 (0.01)^ab	0.78 (0.04)^bc	0.017 (0.000)^a
		10	1.96 (0.24)^b	0.25 (0.01)^a	10.09 (0.64)^b	0.29 (0.00)^abc	0.71 (0.00)^ab	0.019 (0.001)^a
		20	2.90 (0.27)^a	0.24 (0.01)^a	14.12 (0.69)^a	0.38 (0.02)^abc	0.82 (0.01)^a	0.016 (0.001)^a
		p values
		WA	< 0.0001	0.007	< 0.0001	0.001	0.0002	0.03
		N	0.63	0.65	0.49	0.37	0.0009	0.42
		WA * N	0.47	0.007	0.20	0.39	0.01	0.27

Standard errors are shown in parentheses (n = 2). P values are from the result of two-way ANOVA to detect the effect of wood ash and N fertilizer on each soil property 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 soil property across four wood ash levels and N fertilizer treatment.