Ecological stoichiometry controls the transformation and retention of plant-derived organic matter to humus in response to nitrogen fertilisation

Finn, Damien, Page, Kathryn, Catton, Kerrilyn, Kienzle, Marco, Robertson, Fiona, Armstrong, Roger and Dalal, Ram (2016) Ecological stoichiometry controls the transformation and retention of plant-derived organic matter to humus in response to nitrogen fertilisation. Soil Biology and Biochemistry, 99 117-127. doi:10.1016/j.soilbio.2016.05.006


Author Finn, Damien
Page, Kathryn
Catton, Kerrilyn
Kienzle, Marco
Robertson, Fiona
Armstrong, Roger
Dalal, Ram
Title Ecological stoichiometry controls the transformation and retention of plant-derived organic matter to humus in response to nitrogen fertilisation
Journal name Soil Biology and Biochemistry   Check publisher's open access policy
ISSN 0038-0717
1879-3428
Publication date 2016-08-01
Year available 2016
Sub-type Article (original research)
DOI 10.1016/j.soilbio.2016.05.006
Open Access Status Not Open Access
Volume 99
Start page 117
End page 127
Total pages 11
Place of publication Kidlington, Oxford, United Kingdom
Publisher Pergamon Press
Collection year 2017
Language eng
Formatted abstract
Carbon (C) sequestration in soils is a means for increasing soil organic carbon (SOC) stocks and is a potential tool for climate change mitigation. One recommended management practice to increase SOC stocks is nitrogen (N) fertilisation, however examples of positive, negative or null SOC effects in response to N addition exist. We evaluated the relative importance of plant molecular structure, soil physical properties and soil ecological stoichiometry in explaining the retention of SOC with and without N addition. We tracked the transformation of 13C pulse-labelled buffel grass (Cenchrus ciliaris L.), wheat (Triticum aestivum L.) and lucerne (Medicago sativa L.) material to the <53 μm silt + clay soil organic C fraction, hereafter named "humus", over 365-days of incubation in four contrasting agricultural soils, with and without urea-N addition. We hypothesised that: a) humus retention would be soil and litter dependent; b) humus retention would be litter independent once litter C:N ratios were standardised with urea-N addition; and c) humus retention would be improved by urea-N addition. Two and three-way factorial analysis of variance indicated that 13C humus was consistently soil and litter dependent, even when litter C:N ratios were standardised, and that the effect of urea-N addition on 13C humus was also soil and litter dependent. A boosted regression analysis of the effect of 44 plant and soil explanatory variables demonstrated that soil biological and chemical properties had the greatest relative influence on 13C humus. Regression tree analyses demonstrated that the greatest gains in 13C humus occurred in soils of relatively low total organic C, dissolved organic C and microbial biomass C (MBC), or with a combination of relatively high MBC and low C:N ratio. The greatest losses in 13C humus occurred in soils with a combination of relatively high MBC and low total N or increasing C:N ratio. We conclude that soil variables involved in soil ecological stoichiometry exert a greater relative influence on incorporating organic matter as humus compared to plant molecular structure and soil physical properties. Furthermore, we conclude that the effect of N fertilisation on humus retention is dependent upon soil ecological stoichiometry.
Keyword 13C-labelled organic matter
Decomposition
Nitrogen
Soil organic carbon
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: HERDC Pre-Audit
School of Agriculture and Food Sciences
 
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