Mineralisation of soil organic carbon in two Andisols under oil palm: an incubation study into controlling factors

Goodrick, I., and Nelson, P.N. (2018) Mineralisation of soil organic carbon in two Andisols under oil palm: an incubation study into controlling factors. Soil Research, 56 (1). pp. 105-112.

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View at Publisher Website: http://dx.doi.org/10.1071/SR16089


Understanding the factors controlling stability against mineralisation of soil organic matter is important for predicting changes in carbon stocks under changed environment or management. Soil carbon dynamics in oil palm plantations are little studied and have some characteristics that are unusual compared with other agricultural soils, such as high management-induced spatial variability and warm moist conditions. The aim of this work was to determine the factors controlling the mineralisability of the intermediate-stability carbon fraction of volcanic ash surface soils (0–5 and 15–20 cm depth) from oil palm plantations in Papua New Guinea. Soils with carbon contents of 2.2–35.2%, from areas with low and high organic matter inputs, were incubated for up to 812 days and soil respiration was measured periodically. Mean carbon turnover rates were 0.18–1.58, 0.07–0.23 and 0.03–0.07 a–1 on Days 54, 379 and 812 respectively. Turnover rate was initially (Day 54) correlated with pre-incubation total carbon content (r = 0.88), the ratio of permanganate-oxidisable carbon to total carbon (r = 0.62) and the ratio of oxalate-extractable Al and Fe to total carbon (r = –0.51 and –0.54 respectively), but the correlations decreased with time, being insignificant on Day 812. In the soils that had changed from C4 grassland 25 years previously, turnover rate was negatively correlated with d13C, which increased with depth, but d13C did not change significantly over the course of the incubation. Temperature sensitivity of mineralisation varied little, despite large differences in soil properties and changes in mineralisation rate. This suggested that turnover rates were affected to similar extents by biochemical recalcitrance and physical protection, as these two factors influence temperature sensitivity in opposing directions. Physico-chemical protection of organic matter appeared largely related to interaction with poorly crystalline Al and Fe oxides.

Item ID: 52002
Item Type: Article (Research - C1)
ISSN: 1838-6768
Keywords: decomposition, organic matter, organo-mineral interactions, protection, short range order minerals, temperature sensitivity
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A version of this publication was included as Chapter 4 of the following PhD thesis: Goodrick, Iain (2018) Soil carbon dynamics under oil palm plantations. PhD thesis, James Cook University, which is available Open Access in ResearchOnline@JCU. Please see the Related URLs for access.

Funders: Australian Centre for International Agricultural Research (ACIAR)
Projects and Grants: ACIAR SMCN-2009-013
Date Deposited: 15 Jan 2018 23:49
FoR Codes: 41 ENVIRONMENTAL SCIENCES > 4101 Climate change impacts and adaptation > 410101 Carbon sequestration science @ 20%
41 ENVIRONMENTAL SCIENCES > 4106 Soil sciences > 410604 Soil chemistry and soil carbon sequestration (excl. carbon sequestration science) @ 40%
37 EARTH SCIENCES > 3703 Geochemistry > 370304 Organic geochemistry @ 40%
SEO Codes: 96 ENVIRONMENT > 9614 Soils > 961402 Farmland, Arable Cropland and Permanent Cropland Soils @ 50%
82 PLANT PRODUCTION AND PLANT PRIMARY PRODUCTS > 8298 Environmentally Sustainable Plant Production > 829802 Management of Greenhouse Gas Emissions from Plant Production @ 50%
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