Tables
- Phosphorus Availability in an Artificially Flooded Southeastern Floodplain Forest Soil

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Table 1. Physical and chemical characteristics of mesocosm soils collected in January 1992.

Property	Value
Physical
Soil texture, g kg^-1
Sand	622 ± 19
Silt	196 ± 9
Clay	188 ± 17
Chemical
Mean pH	4.9
Organic matter, g kg^-1	91 ± 5
Resin-extractable P_i, mg kg^-1	9.5 ± 1.4
Water-soluble P_o, mg kg^-1	7.2 ± 0.4
0.5 M NaHCO₃, mg kg^-1
P_i	2.61 ± 2.5
P_o	39.3 ± 3.6
Microbial, mg kg^-1
P	109.6 ± 10.7
P_o	8.0 ± 1.5
0.1 M NaOH I, mg kg^-1
P_i	52.0 ± 4.8
P_o	62.5 ± 5.8
0.1 M NaOH II, mg kg^-1 P_i	7.2 ± 0.6
P_o	23.4 ± 2.4
1.0 M HCl P, mg kg^-1	3.9 ± 0.3
Residual P, mg kg^-1	51.4 ± 14.7
Total P, mg kg^-1	375.5 ± 29.0
Total P, mg kg^-1^¶	349.7 ± 21.3
Total N, mg kg^-1	2540.1 ± 162.5

Values are sample means (n = 20) ± standard errors based on the standard deviation of n = 20 sample values divided by the square root of n = 20.

Loss on ignition.

Includes: 0.5 M NaHCO₃ P_i and P_o, microbial P, 0.1 M NaOH I and II P_i, and P_o, 1.0 M HCl P, and residual P.

^¶ Total P from digestion of nonextracted soils.

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Table 2. Comparison of total P supply to in situ AER in treatment soils during flooded periods and nonflooded control soils during those same periods.

		in situ AER
Treatment	Duration of flooding	Flooding treatments	Controls
	mo	_ µg _
FD	3	1972.9 ± 450.8^*	160.2 ± 25.8
+P^¶	3	947.6 ± 212.1^*	160.2 ± 25.8
+N^#	3	776.8 ± 159.2^*	160.2 ± 25.8
PF	4	968.6 ± 223.7^*	192.6 ± 27.6
CF	6	1223.1 ± 197.9^*	299.3 ± 40.0

^* Significant at the 0.05 level.

Values based on means of the total P supply (n = 4 per treatment) for each flooding duration.

Values based on means of the total P supply (n = 4 per control) for each respective time period.

FD = flooded–drained treatment.

^¶ +P = flooded–drained treatment with P additions.

^# N = flooded–drained treatment with N additions.

PF = periodically flooded treatment.

CF = continuously flooded treatment.

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Table 3. Comparison of microbial biomass P in treatment soils during flooded months and control soils during those same months.

	Microbial P
Time	Flooding treatments	Controls
mo	_ mg kg^-1 _
Jul	123.8 ± 7.1^*	152.7 ± 15.7
Aug^¶	84.0 ± 7.2^*	137.8 ± 22.3
Sep^#	57.9 ± 6.3^*	107.5 ± 15.2
Oct	93.5 ± 14.3	126.1 ± 17.4
Nov	94.1 ± 14.0	113.6 ± 19.2
Dec	94.5 ± 17.0	133.0 ± 20.8

^* Significant at the 0.05 level.

Values based on means of treatments (n = 4 per treatment) flooded during the respective month.

Values based on means of controls (n = 4 per control) during the respective month.

Jul = CF (continuously flooded), PF (periodically flooded treatment), FD (flooded–drained), +P (flooded–drained treatment with P additions), +N (flooded–drained treatment with N additions).

^¶ Aug = CF, PF, FD, +P, +N.

^# Sep = CF, FD, +P, +N.

Oct = CF, PF.

Nov = CF, PF.

Dec = CF.

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