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GCTE SOMNET Homepage SOMNET. A Global Network and Database of Soil Organic Matter Models and Long-Term Experimental Datasets.

Pete Smith (SOMNET Coordinator) & Jo Smith
Department of Plant and Soil Science, University of Aberdeen, Cruikshank Building, Aberdeen, AB24 3UU, UK

Pete Falloon (SOMNET Administrator) & David S. Powlson
Sustainable Soils and Grassland Systems Department, Rothamsted Research, Harpenden, U.K. AL5 2BE

Soil organic matter (SOM) plays a central role in nutrient (N, P, S, K) availability, soil stability and the flux of trace greenhouse gases between land surface and the atmosphere. It represents a major pool of carbon within the biosphere, estimated at about 1400-1500 x 1015 g globally, roughly two to three times that in atmospheric CO2 and acts as both a source and a sink for carbon and nutrients. To facilitate scientific progress in predicting the effects on SOM of changes in land-use, agricultural practice and climate, the need for a network of SOM modellers and long-term dataholders was recognised. To fulfil this scientific need, the global Soil Organic Matter Network (SOMNET) was established during 1995 under one-year's funding as a Special Topic of NERC's TIGER rogramme. SOMNET has since attracted contributions from 31 leading SOM modellers and over 120 long-term experimentalists from all around the world (Smith et al., 1996a; Powlson et al., 1998; Smith et al., 1996b, 1997c).

Models and Experiments in SOMNET

SOMNET has rapidly become internationally recognised as an important scientific initiative inthe following ways: a) SOMNET has been adopted by the IGBP's GCTE programme as a Core Project of its focus on Soil Organic Matter, b) SOMNET has been invited to participate in the IPCC's Joint Working Group (with OECD) on Methodologies for Establishing National CO2 Inventories, c) long- term datasets and models selected from SOMNET have been used to complete the most comprehensive evaluation of soil organic matter models undertaken to date (Smith et al., 1997d), in a process begun at a NATO-funded Advanced Research Workshop held at Rothamsted (Powlson et al., 1996). In this exercise, nine leading SOM models were compared for performance in simulating twelve datasets representing different land-uses (arable, grassland, forestry), climatic zones and management practices. Only four models were able to simulate all land-uses (RothC, NCSOIL, CENTURY and SOMM) and a group of six models (RothC, CENTURY, DAISY, CANDY, NCSOIL and DNDC) performed significantly better than did three others (Smith et al., 1997 d & e). SOMNET data is now being used to improve the Rothamsted Carbon Model (Falloon et al, 1998 a & b).

In addition to the model comparison excercise we have also used European datasets from SOMNET (see Smith et al., 1996c) to estimate the potential for carbon sequestration in agricultural soils in the UK (Smith 2000 a, b, c ) the European Union (Smith et al., 1997a) and the wider Europe (Smith et al.,1997b, 1998b, 2000 d, e, 2001).

We have shown in these studies that agronomically realistic scenarios could sequester upto 10% of the anthropogenic CO2 produced in Europe each year or upto 2% of that produced globally. We have also used data to estimate the potential consequences of land-use change following the British BSE crisis (Smith et al, 1996d). Falloon et al. (2000) also used SOMNET data to review the role of inert and refractory OM in SOM models.

The SOMNET project has yielded over 60 peer-reviewed scientific papers. These have appeared in a book of proceedings (of the NATO ARW; Powlson et al., 1996), a Geoderma Journal Special Issue (of the SOM model evaluation and comparison; Smith et al., 1997e) and in other peer- reviewed journals (e.g. Molina & Smith, 1997, Smith et al., 1998 a & c). The project has also yielded a book of model and experimental metadata (Smith et al., 1996b) and a metadata database containing detailed information on all long-term experiments and SOM models mounted for free global access on the World-Wide-Web (Smith et al., 1996a) at URL http://saffron.res.bbsrc.ac.uk/cgi-bin/somnet.

For further information please contact:

Coordinator
Pete Smith
Plant & Soil Science Dept.
Cruickshank Building
University of Aberdeen
Aberdeen AB24 3UU
UK
Tel: +44 (0)1224 272702
Fax: +44 (0)1224 272703
pete.smith@abdn.ac.uk

Administrator/WWW
Pete Falloon
SSC Department
Rothamsted Research
Harpenden, Herts
AL5 2JQ England
Tel: +44 1582 763133
Fax: +44 1582 769222
Fax: +44 1582 760981
pete.falloon@bbsrc.ac.uk

References / Further reading

  1. Falloon, P., Smith, P., Coleman, K. & Marshall, S. 1998a. Estimating the size of the   inert organic matter pool from total soil organic carbon content for use in the Rothamsted Carbon Model. Soil Biology and Biochemistry 30, p1207-1211.
  2. Falloon,P., Smith, P., Smith, J.U., Szab¢, J., Coleman, K. & Marshall, S. 1998b. Regional estimates of carbon sequestration potential: linking the Rothamsted carbon model to GIS databases. Biology and Fertility of Soils 27, p236-241.
  3. Molina, J.A.E. & Smith, P. 1997. Modeling carbon and nitrogen processes in soil. Advances in Agronomy 62: 253-298.
  4. Powlson, D.S., Smith, P., Coleman, K., Smith, J.U., Glendining, M.J., Korschens, M. & Franko, U., 1998. A European network of long-term sites for studies on soil organic matter. Soil and Tillage Research Soil and Tillage Research 47: 263-274.
  5. Powlson, D.S., Smith, P. & Smith, J.U. (Eds.), 1996. In: Evaluation of Soil Organic Matter Models using Existing, Long-Term Datasets. NATO ASI Series I Vol. 38. Springer-Verlag. Berlin. 429pp.
  6. Smith, P., Powlson, D.S., Smith, J.U. & Glendining, M.J., 1996a. The GCTE SOMNET. A global network and database of soil organic matter models and long-term datasets. Soil Use and Management, 12, 104.
  7. Smith, P., Smith, J.U. & Powlson, D.S., 1996b. Soil Organic Matter Network (SOMNET): 1996 Model and Experimental Metadata. GCTE Report 7, GCTE Focus 3,Wallingford, Oxon, 259pp.
  8. Smith, P., Powlson, D.S. & Glendining, M.J., 1996c. Establishing a European soil organic matter network (SOMNET). In: Evaluation of Soil Organic Matter Models using Existing, Long-Term Datasets, (Eds. D.S. Powlson, P. Smith & J.U. Smith), NATO ASI Series I, Vol. 38. Springer-Verlag, Berlin: 81-98.
  9. Smith, P., Smith, J.U. & Powlson, D.S., 1996d. Moving the British cattle herd. Nature, 381: 15.
  10. Smith, P., Powlson, D.S., Glendining, M.J. & Smith, J.U. 1997a. Potential for carbon sequestration in European soils: preliminary estimates for five scenarios using results from long-term experiments. Global Change Biology 3: 67-80.
  11. Smith, P., Powlson, D.S., Glendining, M.J. & Smith, J.U. 1997b. Opportunities and limitations for C sequestration in European agricultural soils through changes in management. In: Management of carbon sequestration in soil. (ed R. Lal, J.M. Kimble, R.F. Follett, & B.A. Stewart) Advances in Soil Science: 143-152.
  12. Smith, P., Powlson, D.S., Smith, J.U., and Falloon, P. 1997c. SOMNET. A Global Network and Database of Soil Organic Matter Models and Long-Term Experimental Datasets. The Globe 38: 4-5.
  13. Smith, P., Smith, J.U., Powlson, D.S., McGill, W.B., Arah, J.R.M., Chertov O.G., Coleman, K., Franko, U., Frolking, S, Jenkinson, D.S., Jensen, L.S., Kelly, R.H., Klein-Gunnewiek, H., Komarov, A., Li, C., Molina, J.A.E., Mueller, T., Parton, W.J., Thornley, J.H.M. & Whitmore, A.P. 1997d. A comparison of the performance of nine soil organic matter models using seven long-term experimental datasets. In: Evaluation and comparison of soil organic matter models using datasets from seven long-term experiments. (Eds: P. Smith, D.S. Powlson, J.U. Smith & E.T. Elliott) Geoderma 81: 153- 225.
  14. Smith, P, Powlson, D.S., Smith, J.U. & Elliott, E.T., 1997e. Evaluation and comparison of soil organic matter models using datasets from seven long-term experiments. Geoderma 81: 1-225.
  15. Smith, P., AndrÆn, O., Brussaard, L., Dangerfield, M., Ekschmitt, K., Lavelle, P. & Tate, K. 1998a. Soil biota and global change at the ecosystem level: describing soil biota in mathematical models. Global Change Biology 4: 773-784.
  16. Smith, P., Powlson, D.S., Glendining, M.J. & Smith, J.U. 1998b. Preliminary estimates of the potential for carbon mitigation in European soils through no-till farming. Global Change Biology 4: 679-685.
  17. Smith, P., Falloon, P., Coleman, K., Smith, J.U., Piccolo, M., Cerri, C.C., Bernoux, M, Jenkinson, D.S., Ingram, J.S.I., Szabó, J. & Pásztor, L. 1999. Modelling soil carbon dynamics in tropical ecosystems. In: Global Climate Change and Tropical Soils. (ed R. Lal, J.M. Kimble, R.F. Follett, & B.A. Stewart) Advances in Soil Science: 341-364.
  18. Falloon, P. & Smith, P. 2000. Modelling refractory organic matter - a review. Biology and Fertility of Soils 30: 388-398.
  19. Smith, P., Powlson, D.S., Smith, J.U., Falloon, P.D. & Coleman, K. 2000a. Meeting the UK's Climate Change Commitments: Options for carbon mitigation on agricultural land. Soil Use and Management 16: 1-11.
  20. Smith, P., Goulding, K.W., Smith, K.A., Powlson, D.S., Smith J.U., Falloon, P.D. & Coleman, K. 2000b. Including trace gas fluxes in estimates of the carbon mitigation potential of UK agricultural land. Soil Use and Management 16: 251-259.
  21. Smith, P., Milne, R., Powlson, D.S., Smith, J.U., Falloon, P.D. & Coleman, K. 2000c. Revised estimates of the carbon mitigation potential of UK agricultural land. Soil Use and Management 16: 293-295.
  22. Smith, P., Powlson, D.S., Smith, J.U., Falloon, P.D. & Coleman, K. 2000d. Meeting Europe's Climate Change Commitments: Quantitative Estimates of the Potential for Carbon Mitigation by agriculture. Global Change Biology 6: 525-539.
  23. Smith, P., Powlson, D.S., Smith, J.U., Falloon, P.D., Coleman K. & Goulding, K.W. 2000e. Agricultural carbon mitigation options in Europe: improved estimates and the global perspective. Acta Agronomica Hungarica 48: 209-216.
  24. Smith, P., Goulding, K.W., Smith, K.A., Powlson, D.S., Smith J.U., Falloon, P.D. & Coleman, K. 2001. Enhancing the carbon sink in European agricultural soils: Including trace gas fluxes in estimates of carbon mitigation potential. Nutrient Cycling in Agroecosystems (in press).

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