Current estimates of soil organic carbon (SOC) are based largely on surficial measurements to depths of 0.3 to 1 m. Many of the world’s soils greatly exceed 1 m depth and there are numerous reports of biological activity to depths of many metres. Although SOC storage to depths of up to 8 m has been previously reported, the extent to which SOC is stored at deeper depths in soil profiles is currently unknown. This paper aims to provide the first detailed analysis of these previously unreported stores of SOC.
Soils from five sites in the deeply weathered regolith in the Yilgarn Craton of south-western Australia were sampled and analysed for total organic carbon by combustion chromatography. These soils ranged between 5 and 38 m (mean 21 m) depth to bedrock and had been either recently reforested with Pinus pinaster or were under agriculture. Sites had a mean annual rainfall of between 399 and 583 mm yr−1.
The mean SOC concentration across all sites was 2.30 ± 0.26 % (s.e.), 0.41 ± 0.05 % and 0.23 ± 0.04 % in the surface 0.1, 0.1–0.5 and 0.5 to 1.0 m increments, respectively. The mean value between 1 and 5 m was 0.12 ± 0.01 %, whereas between 5 and 35 m the values decreased from 0.04 ± 0.002 % to 0.03 ± 0.003 %. Mean SOC mass densities for each of the five locations varied from 21.8–37.5 kg C m−2, and were in toto two to five times greater than would be reported with sampling to a depth of 0.5 m.
This finding may have major implications for estimates of global carbon storage and modelling of the potential global impacts of climate change and land-use change on carbon cycles. The paper demonstrates the need for a reassessment of the current arbitrary shallow soil sampling depths for assessing carbon stocks, a revision of global SOC estimates and elucidation of the composition and fate of deep carbon in response to land use and climate change.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Price includes VAT for USA
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
This is the net price. Taxes to be calculated in checkout.
Aalde H, Gonzalez P, Gytarsky M, Krug T, Kurz WA, Lasco RD, Martino DL, McConkey BG, Ogle S, Paustian K, Raison J, Ravindranath NH, Schoene D, Smith P, Somogyi Z, van Amsel A, Verchot L (2006) Generic methodologies applicable to multiple land-use categories. In: Eggleston S, Buendia L, Miwa K, Ngara T, Tanabe K (eds) IPCC Guidelines for National Greenhouse Gas Inventories, vol 4. Agriculture, Forestry and Other Land Use. IGES, Kanagawa
Anand RR, Paine M (2002) Regolith geology of the Yilgarn Craton, Western Australia: implications for exploration. Aust J Earth Sci 49:3–162
Australian Greenhouse Office (2001) Land clearing: a social history. National Carbon Accounting System Technical Report No. 4. Australian Greenhouse Office, Canberra
Batjes NH (1996) Total carbon and nitrogen in the soils of the world. Eur J Soil Sci 47:151–163
Batjes NH, Sombroek WG (1997) Possibilities for carbon sequestration in tropical and subtropical soils. Glob Change Biol 3:161–173
Camargo PB, Trumbore SE, Martinelli LA, Davidson EA, Nepstad DC, Victoria RL (1999) Soil carbon dynamics in regrowing forest of eastern Amazonia. Glob Change Biol 5:693–702
Canadell J, Jackson RB, Ehleringer JR, Mooney HA, Sala OE, Schulze ED (1996) Maximum rooting depth of vegetation types at the global scale. Oecologia 108:583–595
Churchward HM, Gunn RH (1983) Stripping of deep weathered mantles and its significance to soil patterns. In: Soils: an Australian Viewpoint. CSIRO, Melbourne/Academic Press, London, pp 73–81
Davidson EA, Janssens IA (2006) Temperature sensitivity of soil carbon decomposition and feedbacks to climate change. Nature 440:165–173
Davis JG (1992) Grade control for Australian open pit gold mines. Geological Society, London, Special Publications 63, 219–232. doi:10.1144/GSL.SP.1992.063.01.22
Dell B, Bartle JR, Tacey WH (1983) Root occupation and root channels of jarrah forest subsoils. Aust J Bot 31:615–627
Fearnside PM, Barbosa RI (1998) Soil carbon changes from conversion of forest to pasture in Brazilian Amazonia. For Ecol Manag 108:147–166
Fontaine S, Barot S, Barré P, Bdioui N, Mary B, Rumpel C (2007) Stability of organic carbon in deep soil layers controlled by fresh carbon supply. Nature 450:277–281
Gilkes RJ, Scholz G, Dimmock GM (1973) Lateritic deep weathering of granite. J Soil Sci 24:523–536
Guo LB, Gifford RM (2002) Soil carbon stocks and land use change: a meta analysis. Glob Change Biol 8:345–360
Harper RJ, Beck AC, Ritson P, Hill MJ, Mitchell CD, Barrett DJ, Smettem KRJ, Mann SS (2007) The potential of greenhouse sinks to underwrite improved land management. Ecol Eng 29:329–341
Harper RJ, Sochacki SJ, Smettem KRJ, Robinson N, Silberstein RP, Clarke CJ, McGrath JF, Crombie DS, Hampton CE (2009) Catchment scale evaluation of “Trees, Water and Salt”. Rural Industries Research and Development Corporation, RIRDC Publication Nº 09/059
Harper RJ, Okom AEA, Stilwell AT, Tibbett M, Dean C, George SJ, Sochacki SJ, Mitchell CD, Mann SS, Dods K (2012) Reforesting degraded agricultural landscapes with Eucalypts: effects on soil carbon storage and soil fertility after 26 years. Agric Ecosyst Environ 163:3–13
Harrison RB, Footen PW, Strahm BD (2011) Deep soil horizons: contribution and importance to soil carbon pools and in assessing whole-ecosystem response to management and global change. For Sci 57:67–76
ISSS Working Group RB (1998) World Reference Base for Soil Resources: Introduction. In: Deckers JA, Nachtergaele F, Spaargaren OC (eds) World Reference Base for Soil Resources: Introduction. International Society of Soil Science, International Soil Reference and Information Centre and Food and Agriculture Organization of the United Nations, Leuven, pp 19–26
Jackson RB, Schenk HJ, Jobbágy EG, Canadell J, Colello GD, Dickinson RE, Field CB, Friedlingstein P, Heimann M, Hibbard K, Kicklighter DW, Kleidon A, Neilson RP, Parton WJ, Sala OE, Sykes MT (2000) Belowground consequences of vegetation change and their treatment in models. Ecol Appl 10:470–483
Jackson RB, Banner JL, Jobbágy EG, Pockman WT, Wall DH (2002) Ecosystem carbon loss with woody plant invasion of grasslands. Nature 418:623–626
Jeffrey SJ, Carter JO, Moodie KB, Beswick AR (2001) Using spatial interpolation to construct a comprehensive archive of Australian climate data. Environ Model Softw 16:309–330
Jobbágy EG, Jackson RB (2000) The vertical distribution of soil organic carbon and its relation to climate and vegetation. Ecol Appl 10:423–436
Johnston CD (1987) Preferred water flow and localised recharge in a variable regolith. J Hydrol 94:129–142
Koarashi J, Hockaday WC, Masiello CA, Trumbore SE (2012) Dynamics of decadally cycling carbon in subsurface soils. J Geophys Res 117. doi:10.1029/2012JG002034
Marjoribanks R (2010) Geological techniques in mineral exploration, 2nd edn. Springer, Berlin
McArthur WM (1991) Reference Soils of South-western Australia (WA Branch). Australian Society of Soil Science Inc., Perth, p 265
Milnes AR, Hutton JT (1983) Calcretes in Australia. In: Soils: an Australian Viewpoint. CSIRO, Melbourne/Academic Press, London, pp 119−162
Nabuurs GJ, Masera O, Andrasko K, Benitez-Ponce P, Boer R, Dutschke M, Elsiddig E, Ford-Robertson J, Frumhoff P, Karjalainen T, Krankina O, Kurz WA, Matsumoto M, Oyhantcabal W, Ravindranath NH, Sanchez MJS, Zhang X (2007) Forestry. In: Metz B, Davidson OR, Bosch PR, Dave R, Meyer LA (eds) Climate Change 2007: Mitigation, Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge and New York, pp 541–584
Nepstad DC, Carvalho CR, Davidson EA, Jipp PH, Lefebvre PA, Negrelros GG, da Silva ED, Stone TA, Trumbore SE, Vieira S (1994) The role of deep roots in the hydrological and carbon cycles of Amazonian forests and pastures. Nature 372:666–669
Pan Y, Birdsey RA, Fang J, Houghton R, Kauppi PE, Kurz WA, Phillips OL, Shvidenko A, Lewis SL, Canadell JG, Ciais P, Jackson RB, Pacala SW, McGuire AD, Piao S, Rautiainen A, Sitch S, Hayes D (2011) A large and persistent carbon sink in the world’s forests. Science 333:988–993
Paul KI, Polglase PJ, Nyakuengama JG, Khanna PK (2002) Change in soil carbon following afforestation. For Ecol Manag 168:241–257
Peck AJ, Hatton TJ (2003) Salinity and the discharge of salts from catchments in Australia. J Hydrol 272:191–202
Prescott JA, Pendleton RL (1952) Laterite and lateritic soils. Commonwealth Bureau of Soil Science Technical Communication Nº 47. Commonwealth Agricultural Bureaux, Farnham Royal
Rayment GE, Higginson FR (1992) Australian laboratory handbook of soil and water chemical methods. Inkata Press, Melbourne
Richter DD, Markewitz D (1995) How deep is soil? Bioscience 45:600–609
Robinson N, Harper RJ, Smettem KRJ (2006) Soil water depletion by Eucalyptus spp. integrated into dryland agricultural systems. Plant Soil 286:141–151
Rumpel C, Kögel-Knabner I (2011) Deep soil organic matter—a key but poorly understood component of the terrestial C cycle. Plant Soil 338:143–158
Schenk HJ, Jackson RB (2002) The global biogeography of roots. Ecol Monogr 72:311–328
Schenk HJ, Jackson RB (2005) Mapping the global distribution of deep roots in relation to climate and soil characteristics. Geoderma 126:129–140
Skjemstad J, Spouncer L (2003) Integrated soils modelling for the National Carbon Accounting System (estimating changes in soil carbon resulting from changes in land use). National Carbon Accounting System Technical Report No. 36. Australian Greenhouse Office, Canberra
Sombroek WG, Nachtergaele FO, Hebel A (1993) Amounts, dynamics and sequestration of carbon in tropical and subtropical soils. Ambio 22:417–426
Walkley A, Black IA (1934) An examination of the Degtjareff method for determining soil organic matter and a proposed modification of the chromic acid titration method. Soil Sci 37:29–38
We thank David Chittleborough, Jock Churchman, Guy Kirk, Stan Sochacki, Bernard Dell, Chris Mitchell, Rod Keenan, Keith Smettem and two anonymous reviewers for useful comments, Ian Truckell (Cranfield University) for preparing the Figures, Alex Winter (Forest Products Commission, Western Australia), Marianne Harkins (CSBP), Michael Smirk and Evonne Walker (UWA) for assistance in the field and laboratory and all landholders for access to sites. Drilling was undertaken by the Forest Products Commission (Western Australia) as part of the Australian National Action Plan for Salinity and Water Quality project “Strategic Tree Farming”.
Responsible Editor: Kees Jan van Groenigen.
About this article
Cite this article
Harper, R.J., Tibbett, M. The hidden organic carbon in deep mineral soils. Plant Soil 368, 641–648 (2013). https://doi.org/10.1007/s11104-013-1600-9
- Soil carbon
- Global change