Elsevier

Pedosphere

Volume 33, Issue 3, June 2023, Pages 421-435
Pedosphere

Changes in particulate and mineral-associated organic carbon with land use in contrasting soils

https://doi.org/10.1016/j.pedsph.2022.06.042Get rights and content

Abstract

Soil organic carbon (SOC) is the largest terrestrial carbon (C) stock, and the capacity of soils to preserve organic C (OC) varies with many factors, including land use, soil type, and soil depth. We investigated the effect of land use change on soil particulate organic matter (POM) and mineral-associated organic matter (MOM). Surface (0−10 cm) and subsurface (60−70 cm) samples were collected from paired sites (native and cropped) of four contrasting soils. Bulk soils were separated into POM and MOM fractions, which were analyzed for mineralogy, OC, nitrogen, isotopic signatures, and 14C. The POM fractions of surface soils were relatively unaffected by land use change, possibly because of the continuous input of crop residues, whereas the POM fractions in corresponding subsurface soils lost more OC. In surface soils, MOM fractions dominated by the oxides of iron and aluminum (oxide-OM) lost more OC than those dominated by phyllosilicates and quartz, which was attributed to diverse organic matter (OM) input and the extent of OC saturation limit of soils. In contrast, oxide-OM fractions were less affected than the other two MOM fractions in the subsurface soils, possibly due to OC protection via organo-mineral associations. The deviations in isotopic signature (linked with vegetation) across the fractions suggested that fresh crop residues constituted the bulk of OM in surface soils (supported by greater 14C). Increased isotopic signatures and lower 14C in subsurface MOM fractions suggested the association of more microbially processed, aged OC with oxide-OM fractions than with the other MOM fractions. The results reveal that the quantity and quality of OC after land use change is influenced by the nature of C input in surface soils and by mineral-organic association in subsurface soils.

Section snippets

INTRODUCTION

Globally, organic carbon (OC) content in the top 0−100 cm soil has been estimated to be in the range of 3 500−4 800 Pg carbon (C) (Lehmann and Kleber, 2015), with nearly a quarter of this amount present in the upper 20 cm of soil (Jobbágy and Jackson, 2000; Guo and Gifford, 2002). The soil OC (SOC) pool is much greater than other terrestrial OC pools, e.g., vegetation (420−620 Pg C) and the atmosphere (829 Pg C) (Lehmann and Kleber, 2015). Thus, soils are viewed as a major reservoir and a

Site details

Four sampling locations were selected in New South Wales, Australia, with each location representing a distinct soil type: Ferralsol, Luvisol, Vertisol, and Solonetz. Soil was sampled from paired sites (native and cropped) at each location to investigate the effect of land use conversion on SOC dynamics. The paired sites at each location were directly adjacent and represented similar landscapes, positions, climatic conditions, and major soil characteristics. For each of the four soil types, the

General soil properties

Soils from the paired sites (native and cropped) at both depths were non-saline (EC: 0.09−0.75 dS m−1) and acidic in reaction (pH ≤ 6.8) except for the subsurface soils of the Vertisol, which were slightly alkaline (pH: 7.7−7.8) (Table I). The CEC of each soil did not vary under different land uses but increased with depth for the Luvisol, Vertisol (native), and Solonetz and decreased slightly with depth in the Ferralsol. In general, the Vertisol showed the highest CEC (200−231 mmolc kg−1),

General trends of OC and N

Narrower C:N ratio and larger δ13C and δ15N values of the MOM fractions in contrast to the POM fractions in all soils (Table III) suggest a more advanced phase of OM decomposition in the MOM fractions (Baldock et al., 1992; John et al., 2005). Generally, the C:N ratio in soils decreases with depth (Rumpel and Kögel-Knabner, 2011), which is ascribed to more microbially processed OC (Boström et al., 2007). The C:N ratio of MOM fractions of the subsurface soils in this study also showed an overall

CONCLUSIONS

Land use change (native to cropped) impacted the OC in both surface and subsurface soils. The MOM fractions were not necessarily resistant to land use conversion, particularly in surface soils. Isotopic compositions (δ13C, δ15N, and 14C content) highlighted the effect of vegetation on changes in OC via fresh OM supply to surface soils. Under different OC loading conditions in surface soils, POM was less sensitive because of the continuous input of agricultural crop residues. Among the MOM

ACKNOWLEDGEMENTS

We acknowledge Dr. Claudia Keitel of Centre for Carbon, Water and Food, The University of Sydney, New South Wales, Australia for technical and analytical support in mass spectroscopic analysis. The corresponding author acknowledges the financial support of the International Postgraduate Research Scholarships and Postgraduate Research Support Scheme of the University of Sydney. The authors express gratitude to the Australian Institute of Nuclear Science and Engineering for providing a research

REFERENCES (105)

  • D S Geraei et al.

    Total and labile forms of soil organic carbon as affected by land use change in southwestern Iran

    Geoderma Reg

    (2016)
  • B H Gu et al.

    Adsorption and desorption of different organic matter fractions on iron oxide

    Geochim Cosmochim Acta

    (1995)
  • A Gunina et al.

    Pathways of litter C by formation of aggregates and SOM density fractions: Implications from 13C natural abundance

    Soil Biol Biochem

    (2014)
  • R J Haynes

    Labile organic matter fractions as central components of the quality of agricultural soils: An overview

    Adv Agron

    (2005)
  • J D Jastrow

    Soil aggregate formation and the accrual of particulate and mineral-associated organic matter

    Soil Biol Biochem

    (1996)
  • B John et al.

    Storage of organic carbon in aggregate and density fractions of silty soils under different types of land use

    Geoderma

    (2005)
  • K Kaiser et al.

    The role of DOM sorption to mineral surfaces in the preservation of organic matter in soils

    Org Geochem

    (2000)
  • M Kaiser et al.

    Microbial respiration activities related to sequentially separated, particulate and water-soluble organic matter fractions from arable and forest topsoils

    Soil Biol Biochem

    (2010)
  • J Leifeld et al.

    Soil organic matter fractions as early indicators for carbon stock changes under different land-use?

    Geoderma

    (2005)
  • K Lorenz et al.

    The depth distribution of soil organic carbon in relation to land use and management and the potential of carbon sequestration in subsoil horizons

    Adv Agron

    (2005)
  • Z K Luo et al.

    Soil carbon change and its responses to agricultural practices in Australian agro-ecosystems: A review and synthesis

    Geoderma

    (2010)
  • R Mikutta et al.

    Biogeochemistry of mineral-organic associations across a long-term mineralogical soil gradient (0.3–4100 kyr), Hawaiian Islands

    Geochim Cosmochim Acta

    (2009)
  • T A Ontl et al.

    Factors influencing soil aggregation and particulate organic matter responses to bioenergy crops across a topographic gradient

    Geoderma

    (2015)
  • R L Parfitt et al.

    Effects of clay minerals and land use on organic matter pools

    Geoderma

    (1997)
  • E A Paul et al.

    Dynamics of resistant soil carbon of Midwestern agricultural soils measured by naturally occurring 14C abundance

    Geoderma

    (2001)
  • C Poeplau et al.

    Isolating organic carbon fractions with varying turnover rates in temperate agricultural soils—A comprehensive method comparison

    Soil Biol Biochem

    (2018)
  • S M F Rabbi et al.

    The relationships between land uses, soil management practices, and soil carbon fractions in South Eastern Australia

    Agric Ecosyst Environ

    (2014)
  • C Rumpel et al.

    Stabilisation of HF soluble and HCl resistant organic matter in sloping tropical soils under slash and burn agriculture

    Geoderma

    (2008)
  • M Schrumpf et al.

    Large differences in estimates of soil organic carbon turnover in density fractions by using single and repeated radiocarbon inventories

    Geoderma

    (2015)
  • P Sollins et al.

    Organic C and N stabilization in a forest soil: Evidence from sequential density fractionation

    Soil Biol Biochem

    (2006)
  • Z Tan et al.

    Distribution of light and heavy fractions of soil organic carbon as related to land use and tillage practice

    Soil Till Res

    (2007)
  • M von Lützow et al.

    SOM fractionation methods: Relevance to functional pools and to stabilization mechanisms

    Soil Biol Biochem

    (2007)
  • M Werth et al.

    13C fractionation at the root-microorganisms-soil interface: A review and outlook for partitioning studies

    Soil Biol Biochem

    (2010)
  • S Yeasmin et al.

    Organic carbon characteristics in density fractions of soils with contrasting mineralogies

    Geochim Cosmochim Acta

    (2017)
  • S Ayoubi et al.

    Soil organic carbon physical fractions and aggregate stability influenced by land use in humid region of northern Iran

    Int Agrophys

    (2020)
  • J A Baldock et al.

    Aspects of the chemical structure of soil organic materials as revealed by solid-state 13C NMR spectroscopy

    Biogeochemistry

    (1992)
  • J A Baldock et al.

    Quantifying the allocation of soil organic carbon to biologically significant fractions

    Soil Res

    (2013)
  • T Birch-Thomsen et al.

    Temporal and spatial trends in soil organic carbon stocks following maize cultivation in semi-arid Tanzania, East Africa

    Nutr Cycl Agroecosys

    (2007)
  • B Boström et al.

    Isotope fractionation and 13C enrichment in soil profiles during the decomposition of soil organic matter

    Oecologia

    (2007)
  • S Bruun et al.

    In search of stable soil organic carbon fractions: A comparison of methods applied to soils labelled with 14C for 40 days or 40 years

    Eur J Soil Sci

    (2008)
  • T B Bruun et al.

    Environmental consequences of the demise in swidden cultivation in Southeast Asia: Carbon storage and soil quality

    Hum Ecol

    (2009)
  • T B Bruun et al.

    Organic carbon dynamics in different soil types after conversion of forest to agriculture

    Land Degrad Dev

    (2015)
  • C Chenu et al.

    The influence of cultivation on the composition and properties of clay-organic matter associations in soils

  • C Chenu et al.

    Clay-sized organo-mineral complexes in a cultivation chronosequence: Revisiting the concept of the ‘primary organo-mineral complex’

    Eur J Soil Sci

    (2006)
  • R Chhabra et al.

    The measurement of the cation exchange capacity and exchangeable cations in soils: A new method

  • R T Conant et al.

    Grassland management and conversion into grassland: Effects on soil carbon

    Ecol Appl

    (2001)
  • R T Conant et al.

    Land use effects on soil carbon fractions in the southeastern United States. I. Management-intensive versus extensive grazing

    Biol Fert Soils

    (2003)
  • R T Conant et al.

    Land use effects on soil carbon fractions in the southeastern United States. II. Changes in soil carbon fractions along a forest to pasture chronosequence

    Biol Fert Soils

    (2004)
  • A Don et al.

    Impact of tropical land-use change on soil organic carbon stocks—A meta-analysis

    Global Change Biol

    (2011)
  • K Eusterhues et al.

    Organo-mineral associations in sandy acid forest soils: Importance of specific surface area, iron oxides and micropores

    Eur J Soil Sci

    (2005)
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      POC is formed from fresh or partly decomposed plant materials, often referred to as labile organic C, which are rapidly decomposable (Zimmermann et al., 2007). Thus, POC has a relatively shorter turnover time, and is considered as being more sensitive to management than mineral associated organic C (YEASMIN et al., 2022). As in our study, the literature has previously shown that POC usually increases under reduced tillage and when crop residues are returned to the soil (BEGUM et al., 2022; Jin et al., 2021; Samson et al., 2020).

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