HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (7) Citing Articles via Google Scholar Google Scholar Articles by Blumfield, T. J. Articles by Saffigna, P. G. Search for Related Content PubMed Articles by Blumfield, T. J. Articles by Saffigna, P. G. Agricola Articles by Blumfield, T. J. Articles by Saffigna, P. G. Related Collections Forest Soils Residue management Nutrient Management Nitrogen

DIVISION S-7—FOREST & RANGE SOILS

Decomposition of Nitrogen-15 Labeled Hoop Pine Harvest Residues in Subtropical Australia

^a Cooperative Research Centre for Sustainable Production Forestry, Griffith Univ., Nathan, Qld. 4111, Australia and Faculty of Environmental Sciences, Griffith Univ., Nathan, Qld. 4111, Australia
^b Queensland Forestry Research Institute, P.O. Box 631, Indooroopilly, Qld. 4068, Australia
^c School of Agriculture and Horticulture, Univ. of Queensland, Gatton, Qld. 4343, Australia

^* Corresponding author (t.blumfield{at}griffith.edu.au)

Information on decomposition of harvest residues may assist in the maintenance of soil fertility in second rotation (2R) hoop pine plantations (Araucaria cunninghamii Aiton ex A. Cunn.) of subtropical Australia. The experiment was undertaken to determine the dynamics of residue decomposition and fate of residue-derived N. We used ¹⁵N-labeled hoop pine foliage, branch, and stem material in microplots, over a 30-mo period following harvesting. We examined the decomposition of each component both singly and combined, and used ¹³C cross-polarization and magic-angle spinning nuclear magnetic resonance (¹³C CPMAS NMR) to chart C transformations in decomposing foliage. Residue-derived ¹⁵N was immobilized in the 0- to 5-cm soil layer, with approximately 40% ¹⁵N recovery in the soil from the combined residues by the end of the 30-mo period. Total recovery of ¹⁵N in residues and soil varied between 60 and 80% for the combined-residue microplots, with 20 to 40% of the residue ¹⁵N apparently lost. When residues were combined within microplots the rate of foliage decomposition decreased by 30% while the rate of branch and stem decomposition increased by 50 and 40% compared with rates for these components when decomposed separately. Residue decomposition studies should include a combined-residue treatment. Based on ¹³C CPMAS NMR spectra for decomposing foliage, we obtained good correlations for methoxyl C, aryl C, carbohydrate C and phenolic C with residue mass, ¹⁵N enrichment, and total N. The ratio of carbohydrate C to methoxyl C may be useful as an indicator of harvest residue decomposition in hoop pine plantations.

Abbreviations: CC/MC, carbohydrate C to Methoxyl C ratio • CPMAS NMR, cross-polarization and magic-angle spinning nuclear magnetic resonance