Please use this identifier to cite or link to this item: https://hdl.handle.net/1959.11/30217
Title: Mathematical Functions to Model the Depth Distribution of Soil Organic Carbon in a Range of Soils from New South Wales, Australia under Different Land Uses
Contributor(s): Murphy, Brian W (author); Wilson, Brian  (author)orcid ; Koen, Terry (author)
Publication Date: 2019-07-23
Open Access: Yes
DOI: 10.3390/soilsystems3030046
Handle Link: https://hdl.handle.net/1959.11/30217
Abstract: The nature of depth distribution of soil organic carbon (SOC) was examined in 85 soils across New South Wales with the working hypothesis that the depth distribution of SOC is controlled by processes that vary with depth in the profile. Mathematical functions were fitted to 85 profiles of SOC with SOC values at depth intervals typically of 0–5, 5–10, 10–20, 20–30, 30–40, 40–50, 50–60, 60–70, 70–80, 80–90 and 90–100 cm. The functions fitted included exponential functions of the form SOC = A exp (Bz); SOC = A + B exp (Cz) as well as two phase exponential functions of the form SOC = A + B exp (Cz) + D exp (Ez). Other functions fitted included functions where the depth was a power exponent or an inverse term in a function. The universally best-fitting function was the exponential function SOC = A + B exp (Cz). When fitted, the most successful function was the two-phase exponential, but in several cases this function could not be fitted because of the large number of terms in the function. Semi-log plots of log values of the SOC against soil depth were also fitted to detect changes in the mathematical relationships between SOC and soil depth. These were hypothesized to represent changes in dominant soil processes at various depths. The success of the exponential function with an added constant, the two-phase exponential functions, and the demonstration of different phases within the semi-log plots confirmed our hypothesis that different processes were operating at different depths to control the depth distributions of SOC, there being a surface component, and deeper soil component. Several SOC profiles demonstrated specific features that are potentially important for the management of SOC profiles in soils. Woodland and to lesser extent pasture soils had a definite near surface zone within the SOC profile, indicating the addition of surface materials and high rates of fine root turnover. This zone was much less evident under cropping.
Publication Type: Journal Article
Source of Publication: Soil Systems, 3(3), p. 1-28
Publisher: MDPI AG
Place of Publication: Switzerland
ISSN: 2571-8789
Fields of Research (FoR) 2008: 050301 Carbon Sequestration Science
Fields of Research (FoR) 2020: 410602 Pedology and pedometrics
410101 Carbon sequestration science
410604 Soil chemistry and soil carbon sequestration (excl. carbon sequestration science)
Socio-Economic Objective (SEO) 2008: 961402 Farmland, Arable Cropland and Permanent Cropland Soils
Socio-Economic Objective (SEO) 2020: 180605 Soils
Peer Reviewed: Yes
HERDC Category Description: C1 Refereed Article in a Scholarly Journal
Appears in Collections:Journal Article
School of Environmental and Rural Science

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