Biology and Fertility of Soils

, Volume 27, Issue 2, pp 197–204

Carbon and phosphorus transformations during decomposition of pine forest floor with different phosphorus status

  • S. Saggar
  • R. L. Parfitt
  • G. Salt
  • M. F. Skinner
ORIGINAL PAPER

DOI: 10.1007/s003740050420

Cite this article as:
Saggar, S., Parfitt, R., Salt, G. et al. Biol Fertil Soils (1998) 27: 197. doi:10.1007/s003740050420

Summary

Information on the mineralization of inorganic phosphate (Pi) from organically bound P (Po) during decomposition of forest floor and soil organic matter is vital for understanding P supply in forest ecosystems. Carbon (C) and phosphorus (P) fluxes were determined for forest floor samples from three Pinus radiata plots which had received no P (Control), 62.5 kg P ha–1 (Low P) and 125 kg P ha–1 (High P) 20 years before sampling. The P concentration of the forest floor samples had increased with fertilizer application, and the C:P ratio ranged between 585 and 1465. During a 9-week laboratory incubation 8.2–19.0% of the forest floor C was evolved as CO2-C. The amount of CO2 evolved from the forest floor of the Control plot was more than twice the amounts from the Low P and High P plots. There was little change in net P mineralization in the Control and Low P treatments throughout the incubation, but it increased slightly for the High P samples, suggesting a critical forest floor C:P ratio of 550 for net P mineralization. Changes in the 32P-specific activities of the Pi and microbial P pools during incubation, and concurrent changes in microbial-32P and 32Pi, indicated internal P cycling between these pools. The rate of internal P cycling varied with forest floor quality, and was highest in the High P forest floor. The High P samples had microbial C:P ratios of 22 : 1 which remained constant during the incubation, suggesting the microorganisms had adequate P levels.

Key words Forest floorMicrobial phosphorusMicrobial carbonC:P ratioGross phosphorus mineralization and immobilization

Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • S. Saggar
    • 1
  • R. L. Parfitt
    • 1
  • G. Salt
    • 1
  • M. F. Skinner
    • 2
  1. 1.Landcare Research, Private Bag 11052, Palmerston North, New Zealand Tel.: +64-6-3567154; Fax: +64-6-3559230; e-mail: SaggarS@Landcare.cri.nzNZ
  2. 2.New Zealand Forest Research Institute, Private Bag 3020, Rotorua, New ZealandNZ