Relationship between vertical distributions of Bray II P content and organic P content in the Ap horizon of paddy rice fields

Figures & data

Table 1 Locations, soil classification and P fertilizer rates of the paddy fields studied

Location and tillage (abbreviation)	Classification^†	P fertilizer rate, g P2O5m^−2	Yield of brown rice, g m^−2 (year)
Hachirogata, Akita, no-tillage (HA-NT)	Gley Lowland soil	0	553 (2003)
Hachirogata, Akita, tillage (HA-T)	Gley Lowland soil	6.5	501 (2003)
Utsunomiya, Tochigi, tillage (UM-T)	Andosol	15.2	534 (2001)
Kawatabi, Miyagi, tillage (KA-T)	Non-allophanic Andosol	14.0	558 (2004)
Furukawa, Miyagi, tillage (FU-T)	Gley Lowland soil	7.2	489 (2004)
^†Classification of Cultivated Soils in Japan, Third Approxmation (Classification Committee of Cultivated Soils 1996)

Figure 1  The sampling positions (shaded bars) of soils after harvest for UM-T, KA-T and FU-T from above (a) and vertically (b) from the arrow side of (a). ×, rice stubbles (a); – in (a) and • in (b); the positions of P application through nozzles equipped with the transplanting machine. Schematic representation of depth and width of the soil sampling pit (b).

Table 2 Soil properties of Ap horizon (0–10 cm) in paddy fields after harvest

Soil sample	Texture	pH (H2O)	Oxalate-extractable (g kg^−1)			Pyrophosphate- extractable (g kg^−1)		Alp/Alo	P retetion (%)
			Al (Alo)	Fe (Feo)	Si (Sio)	Al (Alp)	Fe (Fep)
HA-NT	HC	7.7	1.8	8.2	1.0	0.1	1.6	0.08	31
HA-T	HC	7.8	1.8	6.9	1.0	0.1	1.9	0.08	30
UM-T	CL	5.6	64.0	17.8	22.2	11.6	6.2	0.18	97
KA-T	CL	5.8	14.0	9.0	2.3	7.7	6.0	0.55	79
FU-T	CL	6.1	1.7	7.1	0.5	0.5	2.7	0.27	32

Figure 2  Vertical distribution of total carbon (C) in soils which were sampled from the five paddy rice fields as semi-micro thin layers of 0–1, 1–2, 2–3, 3–4, 4–6, 6–8, 8–10, 10–15 and 15–20 cm from the soil surface. (a) No-tillage Hachirougata soil (HA-NT), conventional-tillage Hachirougata soil (HA-T). (b) Conventional-tillage Utsunomiya soil (UM-T), conventional-tillage Kawatabi soil (KA-T), conventional-tillage Furukawa soil (FU-T). Error bars show standard deviation (a: n= 3; b: n= 2).

Figure 3  Vertical distribution of total nitrogen (N) in soils which were sampled from the five paddy rice fields as semi-micro thin layers of 0–1, 1–2, 2–3, 3–4, 4–6, 6–8, 8–10, 10–15 and 15–20 cm from the soil surface. (a) No-tillage Hachirougata soil (HA-NT), conventional-tillage Hachirougata soil (HA-T). (b) Conventional-tillage Utsunomiya soil (UM-T), conventional-tillage Kawatabi soil (KA-T), conventional-tillage Furukawa soil (FU-T). Error bars show standard deviation (a: n= 3; b: n= 2).

Figure 4  Vertical distribution of total phosphorus (P) in soils which were sampled from the five paddy rice fields as semi-micro thin layers of 0–1, 1–2, 2–3, 3–4, 4–6, 6–8, 8–10, 10–15 and 15–20 cm from the soil surface. (a) No-tillage Hachirougata soil (HA-NT), conventional-tillage Hachirougata (HA-T). (b) Conventional-tillage Utsunomiya soil (UM-T), conventional-tillage Kawatabi soil (KA-T), conventional-tillage Furukawa soil (FU-T). Error bars show standard deviation (a: n= 3; b: n= 2).

Figure 5  Vertical distribution of Bray II P in soils which were sampled from the five paddy rice fields as semi-micro thin layers of 0–1, 1–2, 2–3, 3–4, 4–6, 6–8, 8–10, 10–15 and 15–20 cm from the soil surface. (a) No-tillage Hachirougata soil (HA-NT), conventional-tillage Hachirougata soil (HA-T). (b) Conventional-tillage Utsunomiya soil (UM-T), conventional-tillage Kawatabi soil (KA-T), conventional-tillage Furukawa soil (FU-T). Error bars show standard deviation (a: n= 3; b: n= 2).

Table 3 Ratios of Bray II P and Organic P to total P in the five paddy soils

Soil depth (cm)	HA-NT		HA-T		UM-T		KA-T		FU-T
	Bray II P %^a	OP %^b	Bray II P %^a	OP %^b	Bray II P %^c	OP %^d	Bray II P %^a	OP %^b	Bray II P %^a	OP %^b
0–1	11	20	16	15	1.3	30	19	27	21	13
1–2	14	16	19	9	1.0	30	20	27	25	12
2–3	15	11	19	9	1.2	31	19	27	24	11
3–4	17	9	20	8	1.3	30	19	26	24	11
4–6	18	8	21	8	1.3	31	20	26	23	9
6–8	19	7	22	7	1.3	31	19	26	25	11
8–10	18	6	20	7	1.3	32	19	25	25	10
10–15	16	8	22	6	1.3	32	18	26	25	10
15–20	6	12	14	6	1.7	34	15	29	24	11
^aBray II P/Total P × 100, average (n= 3).
^bOrganic P/Total P × 100, average (n= 3).
^cBray II P/Total P × 100, average (n= 2).
^dOrganic P/Total P × 100, average(n= 2).

Figure 6  Vertical distribution of organic phosphorus (P) in soils which were sampled from the five paddy rice fields as semi-micro thin layers of 0–1, 1–2, 2–3, 3–4, 4–6, 6–8, 8–10, 10–15 and 15–20 cm from the soil surface. (a) No-tillage Hachirougata soil (HA-NT), conventional-tillage Hachirougata soil (HA-T). (b) Conventional-tillage Utsunomiya soil (UM-T), conventional-tillage Kawatabi soil (KA-T). (c) Conventional-tillage Furukawa soil (FU-T). Error bars show standard deviation (a: n= 3; b: n= 2; c: n= 2).

Classification Committee of Cultivated Soils . 1996 . Classification of Cultivated Soils in Japan, 3rd approximation , Edited by: Classification Committee of Cultivated Soils . Tsukuba : National Institute of Agro-Environmental Sciences .

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