Improvement of the NH₂OH-HCl-HOAc method for extracting manganese and iron oxides in Japanese Andisols and other soil types in Japan

Figures & data

Table 1 Brief description of soil samples

	Soil classification			Site
Sample	Soil Taxonomy†	Japanese system‡	Horizon	(city, prefecture)	Land use
E-1	Aquents	Gray Fluvic soils	Ap	Suzaka, Nagano	Paddy Field
E-2	Aquents	Gray Fluvic soils	Ap	Tsukubamirai, Ibaraki	Paddy Field
E-3	Aquents	Gray Fluvic soils	Ap	Tochigi, Tochigi	Upland Field
I-1	Udepts	Haplic Brown Forest soils	Ap	Natori, Miyagi	Upland Field
I-2	Udepts	Haplic Brown Forest soils	Ap	Zentuji, Kagawa	Upland Field
I-3	Udepts	Haplic Brown Forest soils	Ap	Kanuma, Tochigi	Upland Field
AA-1	Udands	Allophanic Kuroboku soils	Ap	Tsukuba, Ibaraki	Upland Field
AA-2	Udands	Allophanic Kuroboku soils	Ap	Shimono, Tochigi	Upland Field
AA-3	Udands	Allophanic Kuroboku soils	Bw	Tateyama, Toyama	Forest
AA-4	Udands	Allophanic Kuroboku soils	Bw	Tsukuba, Ibaraki	Upland Field
AA-5	Udands	Allophanic Kuroboku soils	Bw	Chichibu, Saitama	Forest
NA-1	Udands	Non-allophanic Kuroboku soils	A	Oshaki, Miyagi	Forest
NA-2	Udands	Non-allophanic Kuroboku soils	A	Tateyama, Toyama	Forest
NA-3	Udands	Non-allophanic Kuroboku soils	O/A	Chichibu, Saitama	Forest

†According to USDA Soil Taxonomy (Soil Survey Staff 1998). ‡ According to Unified Soil Classification System of Japan 2nd Approximation (The Japanese Sociaty of Pedology 2003). E, Entisols; I, Inceptisols; AA, allophanic Andisols; NA, non-allophanic Andisols.

Table 2 Selected properties of soil samples

Sample†	pH		TC	Fed‡	Alo	Feo	Mnd	Mno	Sio	Alp	Fep	Clay
	(H2O)	(KCl)					g kg^‒1
E-1	6.27	4.74	10.4	16.5	2.19	11.6	0.248	0.202	0.402	0.428	2.04	291
E-2	5.79	4.69	32.7	27.5	5.07	4.65	0.581	0.544	1.57	0.733	1.88	378
E-3	5.91	4.62	17.8	13.9	9.54	6.81	0.667	0.644	2.36	2.40	2.25	219
I-1	6.02	4.55	11.7	19.8	1.72	4.33	0.544	0.516	0.683	0.385	0.818	258
I-2	4.65	3.72	11.6	19.4	1.45	2.12	0.694	0.609	0.151	0.663	0.835	240
I-3	6.66	5.36	30.8	20.2	15.3	5.66	1.35	1.30	3.82	3.03	1.32	76.5
AA-1	7.06	5.75	42.0	55.5	52.1	18.6	1.20	0.918	24.5	3.12	0.479	279
AA-2	6.18	5.23	45.8	30.7	61.6	14.9	0.727	0.640	26.8	3.76	0.761	198
AA-3	4.71	4.22	23.5	23.9	23.0	15.6	0.644	0.581	6.18	4.49	1.60	87.0
AA-4	6.06	5.48	14.0	31.7	72.1	20.1	0.783	0.767	27.6	2.53	0.298	430
AA-5	5.28	4.89	30.0	32.4	42.4	24.0	0.551	0.535	15.2	3.12	0.355	162
NA-1	5.67	4.56	94.2	13.7	19.4	7.76	0.523	0.473	1.84	10.9	4.35	192
NA-2	4.86	3.86	183	17.5	16.3	9.82	0.170	0.141	1.45	8.67	5.85	289
NA-3	3.80	3.47	296	20.1	20.0	17.5	0.118	0.0865	2.83	11.7	9.90	219

† Some data are from Suda et al. (2012).

‡ Subscripts o, d, and p indicate oxalate-, dithionite-citrate-, and pyrophosphate-extractable elements, respectively. H₂O, water; KCl, potassium chloride; TC, total carbon; Fe, iron; Al, aluminum; Mn, manganese; Si, silicon; E, Entisols; I, Inceptisols; AA, allophanic Andisols; NA, non-allophanic Andisols.

Table 3 Amounts of manganese (Mn) extracted with hydroxylamine hydrochloride (NH₂OH-HCl) in acetic acid (HOAc) extractants

		Extracted amounts of Mn (g kg^‒1)
Soil type	Sample	Mno†	NH2OH-HCl concentration
			0.04 mol L^‒1	0.2 mol L^‒1	0.4 mol L^‒1	0.6 mol L^‒1
Entisols	E-1	0.202	0.203	0.249	0.285	0.322
	E-2	0.544	0.710	0.778	0.845	0.935
	E-3	0.644	0.732	0.788	0.769	0.877
	Average	0.463	0.548	0.605	0.633	0.711
	SD	0.232	0.300	0.309	0.303	0.339
Inceptisols	I-1	0.516	0.508	0.545	0.591	0.627
	I-2	0.609	0.774	0.787	0.824	0.831
	I-3	1.30	1.45	1.55	1.64	1.56
	Average	0.810	0.909	0.960	1.02	1.01
	SD	0.431	0.484	0.523	0.549	0.490
Allophanic Andisols	AA-1	0.918	0.985	1.06	1.07	1.17
	AA-2	0.640	0.650	0.722	0.746	0.820
	AA-3	0.581	0.591	0.656	0.685	0.742
	AA-4	0.767	1.01	1.17	1.19	1.27
	AA-5	0.535	0.601	0.682	0.715	0.801
	Average	0.688	0.767	0.859	0.882	0.962
	SD	0.155	0.211	0.240	0.233	0.244
Non-allophanic Andisols	NA-1	0.473	0.531	0.564	0.561	0.664
	NA-2	0.141	0.150	0.165	0.181	0.227
	NA-3	0.0865	0.0895	0.127	0.137	0.175
	Average	0.233	0.257	0.285	0.293	0.356
	SD	0.209	0.239	0.242	0.233	0.269

† Mn_o denotes oxalate-extractable Mn. SD, standard deviation.

Table 4 Rates of extraction of manganese (Mn) oxides with hydroxylamine hydrochloride (NH₂OH-HCl) in acetic acid (HOAc) extractants

		Extraction rate of Mn oxides (%)
		NH2OH-HCl concentration
Soil type	Sample	0.04 mol L^‒1	0.2 mol L^‒1	0.4 mol L^‒1	0.6 mol L^‒1
Entisols	E-1	100	134	160	187
	E-2	140	156	172	193
	E-3	114	123	120	138
	Average	118	138	151	173
	SD	19.9	16.6	27.1	30.4
Inceptisols	I-1	139	144	141	161
	I-2	96.9	111	127	140
	I-3	128	130	136	137
	Average	121	128	135	146
	SD	21.6	16.6	6.94	12.8
Allophanic Andisols	AA-1	113	122	129	114
	AA-2	107	116	117	128
	AA-3	102	113	117	129
	AA-4	102	113	118	128
	AA-5	132	153	155	167
	Average	111	123	127	133
	SD	12.5	16.8	16.6	19.6
Non-allophanic Andisols	NA-1	141	162	157	165
	NA-2	114	121	120	145
	NA-3	108	120	132	169
	Average	121	134	137	160
	SD	18.0	24.2	19.0	13.2
All	Average	117	130	136	150
	SD	15.9	17.3	18.4	23.8

SD, standard deviation.

Table 5 Amounts of iron (Fe) extracted with hydroxylamine-acetic acid (NH₂OH-HOAc) extractants

		Extracted amounts of Fe (g kg^‒1)
		Feo†	Fed	FeHHA
Soil type	Sample			0.04 mol L^‒1	0.2 mol L^‒1	0.4 mol L^‒1	0.6 mol L^‒1
Entisols	E-1	11.6	16.5	11.0	16.8	20.4	25.9
	E-2	4.65	27.5	10.3	16.9	22.5	32.4
	E-3	6.81	13.9	5.62	9.21	12.3	17.4
	Average	7.67	19.3	8.97	14.3	18.4	25.2
	SD	3.54	7.25	2.92	4.42	5.35	7.54
Inceptisols	I-1	4.33	19.8	6.17	13.3	17.6	22.5
	I-2	2.12	19.4	4.69	10.7	15.0	18.7
	I-3	5.66	20.2	6.32	10.2	13.2	18.3
	Average	4.04	19.8	5.73	11.4	15.2	19.8
	SD	1.79	0.427	0.903	1.63	2.21	2.29
Allophanic Andisols	AA-1	18.6	55.5	14.9	24.3	31.6	42.8
	AA-2	14.9	30.7	9.44	15.7	19.6	26.1
	AA-3	15.6	23.9	9.35	15.6	20.0	26.8
	AA-4	20.1	31.7	16.4	28.1	35.7	45.5
	AA-5	24.0	32.4	20.9	31.3	37.0	46.4
	Average	18.7	34.8	14.2	23.0	28.8	21.2
	SD	3.70	12.0	4.91	7.14	8.45	10.2
Non-allophanic Andisols	NA-1	7.76	13.7	6.34	9.95	11.9	16.9
	NA-2	9.82	17.5	8.89	14.7	19.5	26.4
	NA-3	17.5	20.1	11.9	17.3	19.7	25.8
	Average	11.7	17.1	9.03	14.0	17.0	23.0
	SD	5.14	3.20	2.77	3.72	4.42	5.33

† Fe_o and Fe_d denote oxalate-extractable Fe and dithionite-citrate-extractable Fe, respectively. SD, standard deviation.

Table 6 Rates of extraction of iron (Fe) oxides with hydroxylamine hydrochloride (NH₂OH-HCl) in acetic acid (HOAc) extractants

		Extraction rate of short-range ordered Fe oxides (%)				Extraction rate of total Fe oxides (%)
		NH2OH-HCl concentration				NH2OH-HCl concentration
Soil type	Sample	0.04 mol L^‒1	0.2 mol L^‒1	0.4 mol L^‒1	0.6 mol L^‒1	0.04 mol L^‒1	0.2 mol L^‒1	0.4 mol L^‒1	0.6 mol L^‒1
Entisols	E-1	95.1	146	176	224	66.6	102	123	157
	E-2	222	364	484	698	37.4	61.5	81.7	118
	E-3	82.4	135	181	255	40.5	66.4	88.9	126
	Average	133	215	280	392	48.2	76.6	98.0	133
	SD	77.0	129	176	265	16.1	22.1	22.3	20.7
Inceptisols	I-1	143	306	405	519	31.1	66.9	88.6	113
	I-2	221	505	705	883	24.2	55.3	77.4	96.8
	I-3	112	181	233	323	31.3	50.7	65.1	90.6
	Average	158	331	448	575	28.9	57.6	77.0	100
	SD	56.3	163	239	284	4.03	8.37	11.7	11.8
Allophanic Andisols	AA-1	80.0	131	170	230	26.8	43.8	57.0	77.1
	AA-2	63.3	106	131	175	30.8	51.3	63.8	85.1
	AA-3	60.0	100	128	172	39.2	65.3	83.8	112
	AA-4	81.5	139	177	226	51.8	88.7	112.8	144
	AA-5	87.0	130	154	193	64.4	96.4	114.0	143
	Average	74.4	121	152	199	42.6	69.1	86.3	112
	SD	11.9	17.3	22.1	27.6	15.5	22.9	26.6	31.2
Non-allophanic Andisols	NA-1	81.7	128	154	218	46.2	72.4	86.9	123
	NA-2	90.5	149	198	269	50.9	83.9	112	151
	NA-3	67.7	98.7	112	147	59.1	86.1	98.0	128
	Average	80.0	125	155	211	52.1	80.8	98.8	134
	SD	11.5	25.4	43.0	61.2	6.52	7.33	12.3	15.0
All	Average	106	187	244	324	42.9	70.8	89.5	119
	SD	53.0	120	170	220	13.9	18.1	20.4	25.0

SD, standard deviation.

Figure 1 Relationship between hydroxylamine hydrochloride (NH₂OH-HCl) concentration and pH after extraction.

Table 7 Extracted amounts and rates of extraction of iron (Fe) and manganese (Mn) with 0.5 mol L^–1 hydroxylamine hydrochloride (NH₂OH-HCl) (pH 1.5) and with acid oxalate-ascorbic acid solution

				Extracted amounts (g kg^‒1)				Extraction rate of oxides (%)
	Mno†	Feo	Fed	Mn		Fe		Mn		Fe (SRO¶)		Fe (total)
Sample	g kg^‒1			HHmBCR‡	Oxa-Asc§	HHmBCR	Oxa-Asc	HHmBCR	Oxa-Asc	HHmBCR	Oxa-Asc	HHmBCR	Oxa-Asc
E-1	0.202	11.6	16.5	0.178	0.204	8.93	22.7	82.5	101	77.2	196	54.1	138
E-2	0.544	4.65	27.5	0.662	0.457	6.76	30.8	128	79.2	145	662	24.6	112
E-3	0.644	6.81	13.9	0.658	0.541	3.82	18.1	102	83.4	56.1	266	27.6	131
Average	0.463	7.67	19.3	0.499	0.401	6.50	23.9	104	87.9	92.9	375	35.4	127
SD	0.232	3.54	7.25	0.278	0.176	2.56	6.39	22.8	11.6	46.7	251	16.3	13.4
I-1	0.516	4.33	19.8	0.473	0.388	3.33	22.4	90.6	72.0	76.8	518	16.8	113
I-2	0.609	2.12	19.4	0.545	0.451	1.22	21.4	82.5	57.1	57.4	1008	6.29	111
I-3	1.30	5.66	20.2	1.37	1.03	3.10	20.0	105	78.5	54.7	354	15.3	99.2
Average	0.810	4.04	19.8	0.797	0.622	2.55	21.3	92.8	69.2	63.0	627	12.8	108
SD	0.431	1.79	0.427	0.500	0.352	1.16	1.20	11.6	11.0	12.1	340	5.68	7.44
AA-1	0.918	18.6	55.5	0.722	0.158	1.65	15.8	78.2	15.5	8.88	84.7	2.97	28.4
AA-2	0.640	14.9	30.7	0.470	0.430	1.38	18.1	73.1	66.8	9.27	121	4.50	58.9
AA-3	0.581	15.6	23.9	0.518	0.352	0.837	20.8	89.0	59.9	5.37	134	3.50	87.2
AA-4	0.767	20.1	31.7	0.818	0.397	2.71	14.9	107	51.6	13.5	74.1	8.56	47.1
AA-5	0.535	24.0	32.4	0.448	0.266	1.81	17.4	83.6	49.2	7.53	72.3	5.58	53.6
Average	0.688	18.7	34.8	0.595	0.321	1.68	17.4	86.1	48.6	8.90	97.2	5.02	55.0
SD	0.155	3.70	12.0	0.165	0.110	0.686	2.29	12.9	19.8	2.97	28.3	2.21	21.4
NA-1	0.473	7.76	13.7	0.437	0.523	1.42	18.0	92.1	111	18.3	232	10.3	131
NA-2	0.141	9.82	17.5	0.0730	0.156	1.73	26.3	31.1	115	17.6	267	9.91	150
NA-3	0.086	17.5	20.1	0.0701	0.121	2.08	22.4	76.7	149	11.8	128	10.3	111
Average	0.233	11.7	6.50	0.193	0.266	1.74	22.2	66.6	125	15.9	209	10.2	131
SD	0.209	5.14	2.56	0.211	0.222	0.328	4.15	31.7	20.9	3.54	72.5	0.246	19.5

† Subscripts o and d indicate oxalate- ad dithionite-citrate- extractable elements, respectively. ‡ HH_mBCR: 0.5 mol L⁻¹ NH₂OH-HCl (pH 1.5) extraction. § Oxa-Asc: acid oxalate-ascorbic acid extraction. ¶ SRO: Short-range ordered Fe oxides. Mn, manganese; Fe, iron; SD, standard deviation.

Figure 2 Amount of aluminum (Al) extracted from soil samples with different extraction methods. HH_mBCR, HH₀₀₄-A, HH₀₆-A, and Oxa-Asc denote extraction with 0.5 mol L^-1 hydroxylamine hydrochloride (NH₂OH-HCl) (pH 1.5), 0.04 mol L^-1 NH₂OH-HCl in 25% acetic acid (HOAc), 0.6 mol L^-1 NH₂OH-HCl in 25% HOAc, and a mixture of acid oxalate and ascorbic acid, respectively. Bars represent means ± standard deviation (SD) (n = 3).


Figure 3 Amount of silicon (Si) extracted from soil samples with different extraction methods. HH_mBCR, HH₀₀₄-A, HH₀₆-A, and Oxa-Asc denote extraction with 0.5 mol L^-1 hydroxylamine hydrochloride (NH₂OH-HCl) (pH 1.5), 0.04 mol L^-1 NH₂OH-HCl in 25% acetic acid (HOAc), 0.6 mol L^-1 NH₂OH-HCl in 25% HOAc, and a mixture of acid oxalate and ascorbic acid, respectively. Bars represent means ± standard deviation (SD) (n = 3).


Table 8 Comparison of rates of extraction of iron (Fe) and manganese (Mn) oxides, and aluminum (Al)/Fe and silicon (Si)/Fe mole ratios, for four extraction methods

Extraction methods	Extraction rate of oxides (%)			Mole ratio
Soils	Mn	Fe (SRO†)	Fe (total)	Al/Fe	Si/Fe
HHmBCR‡
Entisols	104	92.9	35.4	1.42	0.341
Inceptisols	92.8	63.0	12.8	2.98	0.766
Allophanic	86.1	8.90	50.2	17.7	4.86
Non-allophanic	66.6	15.9	10.2	12.5	0.967
Average	87.5	45.2	27.2	8.65	1.73
SD	15.8	39.9	19.1	7.77	2.10
Oxa-Asc§
Entisols	87.9	375	127	1.23	0.425
Inceptisols	69.2	627	108	1.35	0.450
Allophanic	48.6	93.3	62.6	5.31	1.43
Non-allophanic	125	209	131	2.34	0.392
Average	82.7	326	107	2.56	0.673
SD	32.5	231	31.3	1.90	0.503
HH004-A¶
Entisols	118	133	48.2	0.644	0.354
Inceptisols	121	158	28.9	1.06	0.619
Allophanic	111	74.4	42.6	3.00	0.493
Non-allophanic	121	80.0	52.1	2.18	0.294
Average	118	111	43.0	1.72	0.440
SD	4.69	40.8	10.1	1.07	0.146
HH06-A
Entisols	173	392	133	1.02	0.280
Inceptisols	146	575	100	1.16	0.339
Allophanic	133	199	112	2.27	0.268
Non-allophanic	160	211	134	2.14	0.308
Average	153	345	120	1.65	0.299
SD	17.1	177	16.7	0.647	0.0315

† SRO: Short-range ordered Fe oxides. ‡ HH_mBCR: 0.5 mol L^–1 hydroxylamine hydrochloride (NH₂OH-HCl) (pH 1.5) extraction. § Oxa-Asc: acid oxalate-ascorbic acid extraction. ¶ HH₀₀₄-A, HH₀₆-A: Extraction with 0.04 mol L^–1 and 0.6 mol L^–1 NH₂OH-HCl in 25% acetic acid (HOAc), respectively. SD, standard deviation.

Soil Survey Staff 1998. Keys to Soil Taxonomy, 8th ed, National Resources Conservation Service, Washington, DC.

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Suda A, Makino T, Higashi T 2012: Extractability of manganese and iron oxides in typical Japanese soils by 0.5 mol L–1 hydroxylamine hydrochloride (pH 1.5). Soil Sci. Plant Nutr., 58, 684–695.

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