Table 3.
Quantities and forms of phosphorus extracted by citric acid from five tropical forest soils, as determined using phosphatase hydrolysis, and the mean of all soils. Values expressed as the mean in mg P kg− 1 dry weight soil (± standard error of five field replicates).
| Soil A | Soil B | Soil C | Soil D | Soil E | All plots | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| TP | 8.06 (1.00) | a x | 4.57 (0.78) | a yz | 6.12 (0.57) | a xz | 5.76 (0.25) | a xz | 3.22 (0.18) | a y | 5.55 (0.42) | a |
| RP | 2.68 (0.51) | bc x | 0.57 (0.18) | bc y | 0.79 (0.22) | bc y | 3.07 (0.10) | ab x | 0.87 (0.17) | bc y | 1.60 (0.24) | b |
| UP | 5.38 (0.49) | ac x | 4.00 (0.63) | ad xy | 5.34 (0.38) | a x | 2.69 (0.20) | abc yz | 2.35 (0.05) | ac z | 3.95 (0.31) | a |
| EHP | 3.86 (0.68) | abc x | 2.27 (0.55) | ade x | 2.74 (0.76) | ac x | 1.18 (0.26) | cd xy | 0.40 (0.18) | bd y | 2.09 (0.33) | b |
| NHP | 1.45 (0.26) | b x | 1.37 (0.13) | acde x | 2.54 (0.42) | ac x | 1.51 (0.29) | bcd x | 1.88 (0.22) | ac x | 1.75 (0.14) | b |
| Mono HP | 1.39 (0.15) | b x | 0.32 (0.11) | b y | 0.43 (0.15) | b y | 0.32 (0.06) | e y | 0.26 (0.07) | de y | 0.54 (0.10) | c |
| Nuc HP | 0.28 (0.09) | d xy | 0.75 (0.24) | bce x | 0.92 (0.40) | bc x | 0.03 (0.02) | f y | 0.06 (0.04) | e y | 0.41 (0.11) | c |
| Phytase HP | 2.19 (0.52) | bc x | 1.34 (0.39) | cde x | 1.40 (0.35) | bc x | 0.81 (0.25) | de x | 0.05 (0.07) | e y | 1.16 (0.20) | bc |
| Control | 0.07 (0.03) | d xy | 0.36 (0.11) | b x | 0.06 (0.03) | d xy | 0 (0) | g y | 0.06 (0.04) | e xy | 0.11 (0.03) | d |
TP = total phosphorus, RP = reactive phosphorus, UP = unreactive phosphorus, EHP = enzyme hydrolysable phosphorus (sum of Mono HP, Nuc HP and Phytase HP), NHP = non-hydrolysable phosphorus, Mono HP = monoesterase hydrolysable phosphorus, Nuc HP = nuclease hydrolysable phosphorus, Phytase HP = phytase hydrolysable phosphorus, Control = unreactive phosphorus hydrolyzed during incubation of the control, which had no enzyme addition.
Identical letters (a to g) within a column show non-significant differences among values (p > 0.05).
‡ Identical letters (x to z) across a row indicate non-significant differences among values (p > 0.05.