『Abstract
This study was conducted to investigate the long-term effects
of fire on soil phosphorus (P) and to determine the efficiency
of different procedures in extracting soil P forms. Different
P forms were determined: labile forms (Olsen-P, Bray-P, and P
extracted by anion exchange membranes: AEM-P); moderately labile
inorganic and organic P, obtained by NaOH-EDTA extraction after
removing the AEM-P fraction; and total organic and inorganic soil
P. 31P-NMR spectroscopy was used to characterize the
structure of alkali-soluble P forms (orthophosphate, monoester,
pyrophosphate, and DNA). The studied area was a Pinus pinaster
forest located at Arenas de San Pedro (southern Avila, Spain).
The soils were Dystric Cambisols over granites. Soil samples were
collected at 0-2 cm, 2-5 cm, and 10-15 cm depths, two years after
a fire in the burned area and in an adjacent unburned forest area.
Fire increased the total N, organic C, total P, and organic and
inorganic P content in the surface soil layer. In burned soil,
the P extracted by the sequential procedure (AEM and NaOH + EDTA)
was about 95％ of the total P. Bray extraction revealed a fire-induced
increase in the sorption surfaces. Analysis by chemical methods
overestimated the organic P fraction in the EDTA-NaOH extract
in comparison with the determination by ignition procedure. This
overestimation was more important in the burned than unburned
soil samples, probably due to humification promoted by burning,
which increased P sorption by soil particles. The fire-induced
changes on the structure of alkali-soluble P were an increase
in orthophosphate-P and a decrease in monoester-P and DNA-P.
Keywords: 31P-NMR; Forest fire; P availability; AEM-P』
1. Introduction
2. Material and methods
2.1. Experimental site
2.2. Soil sampling
2.3. Soil analysis
2.4. 31P-NMR measurements
2.5. Statistical analysis
3. Results and discussion
3.1. Fire effect on pH, total organic C, N, and C/N ratio
3.2. Fire effect on total P and organic and inorganic P
3.3. Extractable P
3.4. Liquid-state 31P-NMR spectroscopy determination
4. Conclusions
Acknowledgements
References
※全リンの分析は、Kuo（1996）〔OlsenおよびBray〕による。全有機リンは、Sanders & Williams（1955）による。