Speciation and dynamics of phosphorus in some organically amended soils of southwestern Nigeria

Figures & data

Table 1. Descriptions of sites of the soils used for the study.

Location	State	Longitude	Latitude	Soil Order
Abeokuta	Ogun	N 7° 14.30′	E 3° 26.21′	Alfisol
Odeda	Ogun	N 7° 14.17′	E 3° 31.79′	Alfisol
Ayetoro	Ogun	N 7° 15.00′	E 3° 30.00′	Alfisol
Ibadan	Oyo	N 7° 30.17′	E 3° 54.50′	Alfisol
Ikenne	Ogun	N 6° 50.95′	E 3° 42.57′	Alfisol
Badagry	Lagos	N 6° 25.00′	E 2° 55.00′	Entisol
Okemesi	Ekiti	N 7° 49.00′	E 4° 55.00′	Alfisol
Omu Ijebu	Ogun	N 6° 47.00′	E 3° 52.00′	Alfisol
Imeko	Ogun	N 7° 13.76′	E 3° 25.20′	Ultisol
Igboora	Oyo	N 7° 26.00′	E 3° 17.00′	Alfisol

Table 2. Some initial physico-chemical properties of the soils used in this study.

Soil	Sand	Silt	Clay	Textural	pH	Organic C	Available P	N	Ca	Mg	K	Na	E A	ECEC
Location	g kg^−1			Class	H20	g kg^−1	mg kg^−1	g kg^−1	cmol kg^−1
Abeokuta	772.0	88.0	140.0	LS	6.3	29.0	12.7	1.7	1.88	1.25	0.34	0.29	0.10	3.86
Odeda	912.0	28.0	60.0	S	6.1	24.0	9.8	1.6	0.80	1.21	0.17	0.13	0.11	2.42
Ayetoro	872.0	48.0	80.0	S	6.2	40.8	27.0	3.3	3.25	1.32	0.43	0.30	0.10	5.40
Ibadan	852.0	68.0	80.0	LS	6.3	8.8	17.5	1.0	1.13	1.19	0.28	0.17	0.09	2.86
Ikenne	772.0	88.0	14.00	LS	6.2	26.4	10.6	2.3	1.25	1.20	0.28	0.16	0.10	2.99
Badagry	912.0	28.0	60.0	S	4.8	33.6	39.2	2.0	0.40	1.10	0.13	0.14	0.81	2.58
Okemesi	872.0	118.0	80.0	S	6.3	21.6	11.0	1.5	1.23	1.22	0.27	0.24	0.10	3.06
Omu Ijebu	820.0	72.0	108.0	LS	5.8	21.5	16.1	1.1	1.68	1.20	0.14	0.10	0.30	3.12
Imeko	762.0	60.0	178.0	SL	6.1	28.0	15.4	2.1	1.90	1.26	0.40	0.15	0.20	3.91
Igboora	880.0	52.0	68.0	LS	6.2	21.0	13.3	1.6	1.60	1.10	0.23	0.11	0.14	3.18
Mean	842.6	65.0	86.8		6.0	25.5	17.2	1.8	1.51	1.21	0.27	0.18	0.21	3.34
SD	57.6	28.2	45.7		0.5	8.5	9.2	0.7	0.77	0.07	0.10	0.07	0.22	0.87

Note: LS – Loamy sand; S – Sand; SL – Sandy loam; SD – Standard deviation; EA – Exchangeable acidity; ECEC – Effective Cation Exchange Capacity.

Table 3. Some chemical properties of the poultry manure used.

Parameter	Value (g kg^−1)
Nitrogen	23.6
Phosphorus	14.9
Potassium	14.2
Calcium	4.3
Magnesium	1.8
Iron	7.0
Sulphur	5.7
Organic carbon	128.4
C:N	5.44

Table 4. Initial phosphorus fractions of the soils used in the study.

	Phosphorus fractions (mg kg^−1)
Location	Saloid P	Al-P	Fe-P	Ca-P	Occluded P	Reductant P	Residual P	Organic P	Total P	Bray 1 P
Abeokuta	24.22	19.22	63.82	26.44	94.44	70.74	121.33	115.32	535.53	12.70
Odeda	30.58	16.21	17.83	3.61	92.86	126.36	110.12	82.71	480.28	9.85
Ayetoro	34.07	9.51	12.91	9.68	60.78	64.54	70.67	123.63	385.79	26.99
Ibadan	25.68	21.33	69.10	52.88	106.16	57.36	50.38	110.92	493.81	17.45
Ikenne	35.10	11.42	14.52	10.34	56.43	41.96	92.08	112.65	374.50	10.60
Badagry	27.91	13.67	16.59	1.54	85.73	22.45	66.29	90.32	324.50	12.15
Okemesi	20.32	6.17	20.57	9.68	21.66	48.06	33.42	120.41	280.29	11.02
Omu Ijebu	20.53	12.55	47.32	14.18	30.16	45.86	108.08	125.68	404.36	16.06
Imeko	25.86	10.53	35.90	14.30	80.51	25.77	95.49	98.64	387.00	15.43
Igboora	17.38	5.97	27.18	8.24	12.20	32.60	128.99	101.53	334.09	13.25
Mean	26.17	12.66	32.57	15.09	64.09	53.57	87.69	108.18	400.02	14.55
SD	5.89	5.11	20.81	14.91	32.28	30.06	31.48	14.44	80.99	5.02

Note: SD-Standard deviation.

Table 5. Effects of organic manure application on phosphorus fractions and Bray 1 P of soils of Abeokuta and Odeda at 6 WAI.

Manure rate (t ha^−1)					Phosphorus fractions (mg kg^−1)
	Saloid P	Al-P	Fe-P	Ca-P	Occluded P	Reductant P	Residual P	Organic P	Total P	Bray 1 P
Abeokuta
0	22.54 a	18.26 a	33.19 a	23.45 a	127.86 a	67.92 a	79.72 b	131.49 a	504.43 a	22.36 c
2.5	12.29 b	6.58 b	13.83 b	2.36 c	120.60 a	33.20 b	93.28 ab	148.96 a	431.10 b	22.20 c
5	18.37 ab	1.58 d	13.66 b	2.12 c	123.83 a	20.25 c	108.40 a	168.38 a	456.59 ab	26.35 b
7.5	22.99 a	4.22 c	16.14 b	14.30 b	128.91 a	36.00 b	114.15 a	160.62 a	497.33 a	30.72 a
10	24.73 a	2.53 cd	16.38 b	14.71 b	71.88 b	12.95 c	93.28 ab	170.54 a	407.00 b	33.83 a
Odeda
0	7.52 d	10.24 a	15.39 ab	9.36 a	78.43 a	50.26 b	80.25 b	92.46 b	343.91 ab	14.88 c
2.5	13.02 c	5.05 b	11.44 b	9.56 a	29.46 b	30.95 c	62.88 c	136.94 a	299.30 b	19.99 bc
5	14.90 bc	6.03 b	16.94 a	9.04 a	12.64 c	72.00 a	63.25 c	147.90 a	342.70 ab	26.73 b
7.5	18.80 ab	5.05 b	15.25 ab	8.48 a	10.50 c	54.10 b	107.02 a	160.07 a	379.27 a	36.62 a
10	22.42 a	6.41 b	12.49 ab	8.90 a	6.33 c	56.80 ab	94.48 ab	164.42 a	372.25 a	39.40 a

Note: Means in a column followed by the same letters are not significantly different at 5% probability level.

Table 6. Effects of organic manure application on phosphorus fractions and Bray 1 P of soils of Ayetoro and Ibadan at 6 WAI.

Manure rate (t ha^−1)					Phosphorus fractions (mg kg^−1)
	Saloid P	Al-P	Fe-P	Ca-P	Occluded P	Reductant P	Residual P	Organic P	Total P	Bray 1 P
Ayetoro
0	28.67 ab	10.42 ab	28.44 c	14.40 b	73.58 bc	91.20 b	80.12 a	162.43 b	488.07 b	30.10 d
2.5	31.10 a	11.99 a	48.40 b	27.63 a	79.82 bc	42.85 d	63.74 c	206.86 ab	512.39 b	35.64 c
5	20.68 b	10.42 ab	92.26 a	17.17 b	54.65 c	91.15 b	69.57 bc	229.02 a	584.92 a	42.06 b
7.5	20.83 b	10.42 ab	35.88 c	27.10 a	86.10 ab	66.95 c	78.85 ab	236.90 a	563.03 ab	39.02 b
10	28.06 ab	6.94 b	34.60 c	12.39 b	115.51 a	125.45 a	83.19 a	224.34 a	630.48 a	51.34 a
Ibadan
0	21.98 bc	18.21 a	72.96 a	4.25 a	29.41 c	57.20 a	80.12 a	110.87 b	395.50 b	33.92 a
2.5	17.07 c	11.05 bc	58.45 b	3.88 a	44.11 bc	15.67 b	67.06 b	142.45 ab	359.74 b	41.27 a
5	26.32 bc	5.37 cd	36.42 c	2.42 a	50.41 b	32.05 ab	52.11 c	170.97 ab	376.07 b	42.65 a
7.5	41.65 a	4.74 d	37.50 c	4.42 a	44.11 bc	18.55 b	46.59 c	176.58 a	374.14 b	40.07 a
10	34.13 ab	14.84 a	40.03 c	3.72 ab	92.41 a	48.40 a	71.20 ab	181.82 a	486.55 a	42.40 a

Note: Means in a column followed by the same letters are not significantly different at 5% probability level.

Table 7. Effects of organic manure application on phosphorus fractions and Bray 1 P of soils of Ikenne and Badagry at 6 WAI.

Manure rate (t ha^−1)					Phosphorus fractions (mg kg^−1)
	Saloid P	Al-P	Fe-P	Ca-P	Occluded P	Reductant P	Residual P	Organic P	Total P	Bray 1 P
Ikenne
0	25.74 a	9.15 ab	11.43 c	3.28 b	45.70 a	38.54 b	48.51 bc	126.96 a	309.31 bc	19.66 c
2.5	29.79 a	10.73 a	4.34 c	3.60 b	33.62 bc	28.51 c	42.61 c	153.76 a	306.60 c	31.42 b
5	35.58 a	11.69 a	23.40 b	7.42 a	35.70 b	16.90 d	58.53 a	182.82 a	372.04 ab	44.14 a
7.5	36.16 a	11.36 a	47.33 a	6.36 a	12.62 d	43.30 b	54.56 ab	184.82 a	396.51 a	39.65 ab
10	31.60 a	5.43 b	25.62 b	8.92 a	26.81 c	56.25 a	56.67 ab	190.50 a	401.80 a	37.99 ab
Badagry
0	7.47 b	10.14 a	32.80 ab	10.60 b	90.23 b	23.90 a	64.19 a	100.72 a	340 00 ab	43.77 a
2.5	9.97 b	4.33 b	42.88 a	35.63 a	129.84 a	17.45 b	56.49 ab	101.51 a	398.10 a	45.63 a
5	19.10 a	2.27 c	15.28 c	6.99 b	108.16 ab	19.15 ab	59.43 ab	112.97 a	343.44 ab	46.89 a
7.5	19.45 a	3.37 bc	20.80 bc	13.66 b	93.31 b	6.20 c	64.77 a	115.70 a	337.05 ab	46.18 a
10	19.82 a	4.19 bc	14.86 c	6.46 b	87.84 b	16.20 b	51.15 b	121.38 a	321.90 b	42.31 a

Note: Means in a column followed by the same letters are not significantly different at 5% probability level according to LSD.

Table 8. Effects of organic manure application on phosphorus fractions and Bray 1 P of soils of Okemesi and Omu Ijebu at 6 WAI.

Manure rate (t ha^−1)					Phosphorus fractions (mg kg^−1)
	Saloid P	Al-P	Fe-P	Ca-P	Occluded P	Reductant P	Residual P	Organic P	Total P	Bray 1 P
Okemesi
0	13.79 b	5.26 a	17.44 c	1.91 d	18.34 a	30.77 b	29.50 b	110.15 b	227.16 b	21.82 c
2.5	15.94 b	4.32 a	18.28 c	2.65 d	16.71 a	5.65 c	40.78 b	112.26 b	216.59 b	34.04 b
5	67.94 a	4.86 a	42.88 a	11.44 a	24.11 a	37.15 b	39.92 b	129.64 ab	357.94 a	36.87 b
7.5	25.85 b	3.97 a	12.34 d	4.98 c	22.00 a	86.65 a	35.19 b	150.95 a	341.93 a	37.53 b
10	19.10 b	5.11 a	30.36 b	7.94 b	23.81 a	25.90 b	79.51 a	142.73 ab	334.46 a	47.92 a
Omu-Ijebu
0	23.84 a	6.78 a	38.06 a	16.31 a	34.21 b	32.65 a	97.11 a	175.02 a	423.98 ab	18.95 a
2.5	21.85 a	7.41 a	29.5 b	17.36 a	46.41 a	90.55 b	83.70 ab	183.94 a	480.72 a	20.45 a
5	11.20 b	9.78 a	12.78 c	4.22 b	46.9 a	47.25 b	47.60 d	202.27 a	382.00 b	20.12 a
7.5	10.05 b	8.59 a	9.76 c	5.82 b	44.32 a	42.20 b	61.15 cd	201.32 a	383.21 b	20.41 a
10	9.34 b	9.38 a	12.08 c	13.24 a	51.12 a	34.52 b	71.35 bc	205.85 a	406.88 ab	22.20 a

Note: Means in a column followed by the same letters are not significantly different at 5% probability level according to LSD.

Table 9. Effects of organic manure application on phosphorus fractions and Bray 1 P of soils of Imeko and Igboora at 6 WAI.

Manure rate (t ha^−1)					Phosphorus fractions (mg kg^−1)
	Saloid P	Al-P	Fe-P	Ca-P	Occluded P	Reductant P	Residual P	Organic P	Total P	Bray 1 P
Imeko
0	19.19 b	4.60 a	13.16 b	9.74 a	48.26 bc	10.88 ab	64.43 b	108.91 a	279.17 abc	28.76 c
2.5	14.79 b	1.84 b	19.74 a	5.76 b	24.63 d	6.20 b	64.92 b	111.58 a	249.46 c	31.96 c
5	20.25 b	2.32 b	10.40 b	4.78 bc	75.62 a	7.75 b	82.37 a	110.77 a	314.26 ab	58.43 a
7.5	52.14 a	3.09 ab	12.70 b	4.20 c	34.61 cd	8.45 b	36.63 c	124.72 a	276.54 bc	48.58 b
10	54.00 a	4.18 a	11.76 b	5.62 b	51.82 b	19.25 a	45.78 c	127.84 a	320.25 a	53.55 ab
Igboora
0	29.16 b	3.17 b	9.56 a	3.78 b	51.21 a	39.25 a	58.83 b	110.59 a	305.55 a	18.67 c
2.5	50.41 a	3.28 b	12.50 a	4.35 b	19.50 b	28.55 b	72.49 a	130.82 a	321.90 a	35.06 b
5	34.47 b	2.98 c	11.72 a	6.74 a	21.20 b	13.55 c	73.78 a	139.36 a	303.80 a	41.49 ab
7.5	31.89 b	4.34 ab	9.82 a	6.09 a	17.11 b	11.25 c	71.22 a	122.83 a	274.55 a	47.96 a
10	36.48 ab	5.76 a	8.92 a	4.14 b	19.52 b	29.80 b	69.22 a	134.75 a	308.59 a	46.45 a

Note: Means in a column followed by the same letters are not significantly different at 5% probability level according to LSD.

Table 10. Effects of organic manure application on phosphorus fractions and Bray 1 P in pot experiments using Abeokuta soil sample.

Cycle	Manure rate (t ha^−1)					Phosphorus fractions (mg kg^−1)
		Saloid P	Al-P	Fe-P	Ca-P	Occluded P	Reductant P	Residual P	Organic P	Total P	Bray 1 P
First	0	10.70 d	6.90 a	8.44 a	7.08 a	12.42 d	11.80 b	184.63 bc	126.09 a	368.10 c	14.87 b
	2.5	12.58 cd	5.68 ab	9.62 a	5.98 a	22.76 bc	15.55 b	283.49 a	143.27 a	498.93 b	19.28 ab
	5.0	19.24 ab	3.79 bc	9.95 a	6.14 a	24.80 b	11.70 b	249.18 ab	155.78 a	480.58 b	21.73 a
	7.5	18.37 bc	3.16 c	10.41 a	6.42 a	16.53 cd	14.80 b	147.23 c	148.62 a	365.54 c	23.27 a
	10.0	25.17 a	4.74 abc	10.08 a	5.74 a	59.82 a	30.90 a	308.22 a	167.12 a	611.79 a	23.31 a
Second	0	8.42 a	5.62 a	10.04 c	6.42 b	3.12 c	2.48 b	92.86 bc	110.78 b	239.74 c	20.44 b
	2.5	4.60 b	0.38 c	23.53 b	10.65 a	1.20 e	3.66 b	84.06 cd	152.55 a	280.63 b	50.71 a
	5.0	3.45 b	2.85 b	20.82 b	11.12 a	5.20 b	5.24 a	79.02 d	142.21 a	269.91 bc	55.32 a
	7.5	8.77 a	3.10 b	38.84 a	12.67 a	6.90 a	6.30 a	94.27 b	132.37 ab	303.22 ab	54.46 a
	10.0	9.50 a	0.52 c	23.81 b	14.49 a	2.18 d	3.24 b	104.45 a	155.97 a	314.16 a	58.12 a
Third	0	6.50 b	0.21 b	14.49 d	5.00 c	1.09 bc	0.52 c	82.46 b	102.56 c	212.83 d	25.56 b
	2.5	2.90 d	0.41 b	45.47 ab	9.52 bc	0.73 c	0.84 b	93.65 ab	158.09 a	311.61 a	53.82 a
	5.0	4.30 cd	0.36 b	29.09 c	14.75 b	2.30 a	0.53 c	86.34 ab	128.44 b	266.11 c	60.76 a
	7.5	5.70 bc	1.28 a	54.18 a	13.73 b	0.18 d	0.31 c	97.56 a	112.31 bc	285.25 bc	63.83 a
	10.0	10.70 a	0.63 b	41.79 b	22.50 a	1.27 b	4.08 a	91.06 ab	132.14 b	304.17 ab	58.13 a

Note: Means in a column followed by the same letters within cycle are not significantly different at 5% probability level.

Table 11. Effects of organic manure application on phosphorus fractions and Bray 1 P in pot experiments using Odeda soil sample.

Cycle	Manure rate (t ha^−1)					Phosphorus fractions (mg kg^−1)
		Saloid P	Al-P	Fe-P	Ca-P	Occluded P	Reductant P	Residual P	Organic P	Total P	Bray 1 P
First	0	19.96 c	3.79 b	16.14 bc	2.96 b	6.30 b	75.95 ab	82.56 a	107.81 b	315.52 a	12.55 d
	2.5	18.51 c	6.31 b	15.70 bc	9.43 a	16.36 a	56.25 c	69.13 ab	130.65 ab	322.34 a	19.90 c
	5.0	22.99 bc	5.05 b	23.78 ab	4.55 b	6.30 b	83.82 a	73.19 ab	142.34 ab	362.10 a	26.80 b
	7.5	28.35 ab	6.63 b	9.74 c	8.40 a	4.25 b	64.70 bc	79.62 a	145.69 a	347.38 a	31.59 b
	10.0	30.22 a	12.31 a	28.16 a	7.64 a	16.84 a	10.50 d	43.11 b	150.21 a	298.64 a	42.12 a
Second	0	1.90 d	2.56 a	14.66 c	3.24 c	2.24 b	1.20 b	89.34 ab	112.22 c	227.36 c	25.28 b
	2.5	2.20 d	0.73 cd	18.06 bc	9.34 b	9.52 a	1.99 ab	72.07 b	138.35 b	245.28 b	54.13 a
	5.0	6.24 c	0.45 d	28.72 a	12.88 b	3.33 b	2.23 a	81.15 ab	149.48 a	284.48 a	57.97 a
	7.5	9.86 b	1.62 b	20.23 b	10.52 b	2.48 b	1.98 ab	95.92 a	156.33 a	298.94 a	56.82 a
	10.0	16.40 a	1.29 bc	26.42 a	23.10 a	4.36 b	2.51 a	69.84 b	159.45 a	303.37 a	59.17 a
Third	0	3.60 cd	0.84 c	26.15 b	4.76 d	0.46 c	0.94 a	70.86 c	92.6 c	200.21 d	23.16 b
	2.5	1.90 d	0.96 c	33.50 b	8.59 c	1.09 b	2.12 c	83.52 b	122.78 bc	254.46 c	48.73 a
	5.0	4.40 c	1.46 b	36.23 b	17.37 b	0.36 c	3.24 b	92.06 ab	156.03 a	311.15 b	61.15 a
	7.5	8.80 b	2.01 a	29.44 b	12.14 c	1.09 b	2.42 c	101.44 a	150.75 ab	308.09 b	54.94 a
	10.0	15.00 a	0.86 c	58.17 a	39.83 a	3.27 c	3.97 a	86.92 b	167.04 a	375.06 a	64.14 a

Note: Means in a column followed by the same letters within cycle are not significantly different at 5% probability level.

Table 12. Effects of organic manure application on phosphorus fractions and Bray 1 P in pot experiments using Ayetoro soil sample.

Cycle	Manure rate (t ha^−1)					Phosphorus fractions (mg kg^−1)
		Saloid P	Al-P	Fe-P	Ca-P	Occluded P	Reductant P	Residual P	Organic P	Total P	Bray 1 P
First	0	29.94 b	5.68 b	18.68 b	6.56 b	68.22 a	40.05 c	76.44 b	153.87 a	399.44 b	19.07 a
	2.5	33.12 ab	5.05 b	27.10 a	15.08 a	90.33 a	32.46 c	108.03 a	180.52 a	491.69 a	20.36 a
	5.0	32.40 ab	8.84 a	13.38 c	13.24 a	75.69 a	103.50 a	39.95 d	208.21 a	495.21 a	19.28 a
	7.5	35.00 ab	7.89 a	17.26 bc	7.86 b	21.12 a	73.15 b	70.45 bc	210.06 a	442.79 ab	19.74 a
	10.0	37.31 a	4.74 b	19.69 b	17.62 a	27.30 b	71.85 b	48.29 cd	230.45 a	457.10 ab	26.18 a
Second	0	8.56 b	1.24 a	35.43 a	32.24 a	4.66 b	5.56 a	89.34 ab	142.88 c	319.91 cd	28.53 c
	2.5	6.30 b	1.36 a	26.08 b	37.35 a	5.81 ab	6.89 a	72.07 bc	155.74 c	311.60 d	38.26 bc
	5.0	13.23 a	1.98 a	22.98 b	20.21 bc	7.69 a	3.58 b	81.15 abc	188.90 b	339.72 c	32.07 bc
	7.5	11.54 a	2.02 a	37.04 a	24.45 b	8.22 a	5.88 a	95.92 a	212.83 ab	397.90 a	46.85 ab
	10.0	12.70 a	1.14 a	36.23 a	14.94 c	6.18 ab	6.06 a	69.84 c	221.05 a	368.14 b	55.26 a
Third	0	5.40 a	0.70 c	49.77 c	13.16 c	4.72 b	4.81 c	70.86 b	122.65 d	272.07 c	35.81 b
	2.5	6.40 a	3.95 a	26.08 d	13.17 c	9.63 a	8.99 a	83.52 ab	150.14 c	301.88 c	35.04 b
	5.0	8.10 a	2.19 b	77.70 a	23.33 b	4.36 b	4.00 c	92.06 a	174.31 bc	386.05 ab	37.71 b
	7.5	7.40 a	1.77 b	63.95 b	41.74 a	3.27 b	4.29 c	100.68 a	195.54 ab	418.64 a	44.35 ab
	10.0	5.70 a	0.55 c	50.72 c	12.89 c	7.81 a	6.17 b	86.92 ab	204.82 a	375.58 b	63.01 a

Note: Means in a column followed by the same letters within cycle are not significantly different at 5% probability level.

Table 13. Effects of organic manure application on phosphorus fractions and Bray 1 P in pot experiments using Ibadan soil sample.

Cycle	Manure rate (t ha^−1)					Phosphorus fractions (mg kg^−1)
		Saloid P	Al-P	Fe-P	Ca-P	Occluded P	Reductant P	Residual P	Organic P	Total P	Bray 1 P
First	0	26.90 a	9.21 bc	25.78 a	3.40 b	42.12 a	66.40 a	60.69 a	114.80 a	349.30 a	34.36 b
	2.5	28.70 a	4.30 c	30.49 a	3.06 b	10.54 c	23.65 b	59.12 b	167.91 a	307.77 a	38.02 b
	5.0	31.10 a	4.42 c	23.40 a	8.50 a	12.65 c	28.70 b	65.67 a	155.87 a	330.31 a	36.65 b
	7.5	35.72 a	16.73 a	29.04 a	8.38 a	31.50 ab	21.42 bc	39.82 b	170.43 a	353.04 a	42.17 ab
	10.0	39.71 a	12.94 ab	28.91 a	11.40 a	18.95 bc	12.80 c	46.09 b	183.38 a	353.28 a	48.03 a
Second	0	4.28 b	1.20 a	25.24 a	8.24 c	8.29 a	2.40 b	91.31 b	116.34 c	257.30 c	45.07 c
	2.5	4.80 b	0.92 a	27.41 a	32.68 a	5.24 b	1.15 b	88.24 bc	175.77 ab	336.21 b	86.39 a
	5.0	20.04 a	0.60 b	15.55 b	8.21 c	3.50 bc	3.25 b	112.19 a	160.74 b	324.08 b	72.32 b
	7.5	22.74 a	0.56 b	17.98 b	9.24 c	2.20 cd	2.60 b	82.90 bc	182.39 ab	320.61 b	76.61 ab
	10.0	25.70 a	0.11 c	25.73 a	16.23 b	1.45 d	7.53 a	76.28 c	194.43 a	347.46 a	89.42 a
Third	0	5.30 c	0.81 ab	32.32 a	16.62 b	5.33 a	4.61 bc	97.73 abc	104.46 d	267.18 c	50.24 d
	2.5	6.20 c	0.41 cd	36.44 a	27.03 a	4.89 a	5.92 b	101.84 a	142.29 bc	325.02 ab	63.59 c
	5.0	13.70 b	0.33 d	20.46 b	21.38 ab	3.94 a	3.88 bc	100.98 ab	139.33 c	304.00 bc	82.10 ab
	7.5	17.40 ab	0.72 bc	11.34 c	19.04 b	5.08 a	2.76 c	81.57 c	178.52 a	316.43 b	85.05 a
	10.0	20.10 a	1.11 a	24.36 b	15.66 a	5.21 a	9.09 a	83.45 bc	171.54 ab	330.52 a	75.26 b

Note: Means in a column followed by the same letters within cycle are not significantly different at 5% probability level.

Table 14. Effects of organic manure application on phosphorus fractions and Bray 1 P in pot experiments using Ikenne soil sample.

Cycle	Manure rate (t ha^−1)					Phosphorus fractions (mg kg^−1)
		Saloid P	Al-P	Fe-P	Ca-P	Occluded P	Reductant P	Residual P	Organic P	Total P	Bray 1 P
First	0	14.22 c	7.52 a	9.52 a	7.00 a	34.82 b	8.45 a	46.54 c	139.67 a	267.74 b	13.42 b
	2.5	14.36 c	5.43 a	13.45 a	4.04 b	39.17 ab	8.10 a	71.36 a	173.25 a	329.16 ab	20.36 b
	5.0	31.40 b	8.73 a	11.46 a	7.64 a	42.20 ab	5.65 a	44.97 c	150.52 a	302.57 ab	36.65 a
	7.5	25.82 b	7.79 a	12.49 a	3.38 b	40.21 ab	6.15 a	49.78 bc	166.65 a	312.27 ab	42.55 a
	10.0	40.93 a	8.29 a	14.93 a	4.06 b	59.61 a	4.56 a	60.49 ab	176.08 a	368.95 a	39.68 a
Second	0	12.23 b	1.10 b	8.78 c	5.24 b	5.54 a	5.43 a	62.04 c	102.54 d	202.90 c	30.82 c
	2.5	11.70 b	0.58 c	8.61 c	4.88 b	3.69 ab	4.68 ab	82.62 ab	132.43 b	249.19 b	65.23 b
	5.0	14.30 b	0.78 bc	12.21 bc	10.66 a	4.03 ab	3.35 ab	65.65 c	155.98 a	266.96 ab	73.08 ab
	7.5	17.45 ab	1.50 a	19.32 a	15.48 a	3.32 ab	3.41 ab	98.25 a	118.72 c	277.45 a	82.23 a
	10.0	24.60 a	0.67 c	15.54 ab	13.57 a	1.82 b	2.72 b	73.36 bc	123.16 c	255.44 ab	85.63 a
Third	0	7.00 bc	0.30 b	9.40 c	1.96 d	2.63 a	0.53 c	71.38 b	89.65 a	182.85 c	24.75 b
	2.5	24.60 a	2.06 a	12.81 c	2.05 d	0.55 b	1.33 b	95.23 a	110.23 a	248.86 b	58.20 a
	5.0	10.10 bc	2.34 a	19.22 b	24.93 b	0.18 b	3.21 a	99.24 a	120.06 a	279.28 a	56.42 a
	7.5	4.70 c	1.70 a	25.62 a	15.13 c	0.20 b	2.96 a	67.43 b	110.96 a	228.70 b	58.43 a
	10.0	12.30 b	0.11 b	27.72 a	32.22 a	2.18 a	3.04 a	59.82 b	115.65 a	253.04 b	51.64 a

Note: Means in a column followed by the same letters within cycle are not significantly different at 5% probability level.

Table 15. The tissue concentrations of Phosphorus in soya bean leaves in the three cycles of pot experiments.

Cycle	Manure rate (t ha^−1)	% P
		Abeokuta	Odeda	Ayetoro	Ibadan	Ikenne
First	0	0.12 ab	0.07 cd	0.06 d	0.06 b	0.06 b
	2.5	0.10 b	0.03 d	0.11 cd	0.10 ab	0.06 b
	5.0	0.12 ab	0.10 bc	0.19 bc	0.07 ab	0.09 a
	7.5	0.18 a	0.14 b	0.27 a	0.11 a	0.10 a
	10.0	0.16 ab	0.37 a	0.23 ab	0.09 ab	0.07 b
Second	0	0.09 d	0.05 c	0.07 d	0.09 a	0.07 d
	2.5	0.08 d	0.11 bc	0.16 c	0.08 b	0.10 cd
	5.0	0.18 c	0.08 c	0.30 b	0.07 b	0.12 bc
	7.5	0.31 a	0.19 b	0.41 a	0.12 ab	0.16 a
	10.0	0.25 b	0.46 a	0.38 a	0.15 a	0.14 ab
Third	0	0.14 c	0.03 c	0.11 d	0.05 d	0.05 d
	2.5	0.17 bc	0.12 b	0.14 d	0.19 bc	0.12 c
	5.0	0.27 b	0.13 b	0.26 c	0.16 c	0.13 c
	7.5	0.24 bc	0.16 b	0.36 b	0.24 b	0.23 b
	10.0	0.39 a	0.23 a	0.45 a	0.34 a	0.36 a

Note: Means in a column followed by the same letters within cycle are not significantly different at 5% probability level.