1. General Model Information

Name: A model for the turnover of carbon in soil

Acronym: ROTHC-26.3

Contact:

Author(s):

Abstract:

RothC-26.3 is a model for the turnover of organic carbon in non-waterlogged topsoils that allows for the effects of soil type, temperature, moisture content and plant cover on the turnover process. It uses a monthly time step to calculate total organic carbon (t ha^-1), microbial biomass carbon (t ha^-1) and \Delta¹⁴C (from which the equivalent radiocarbon age of the soil can be calculated) on a years to centuries timescale. (Coleman and Jenkinson, 1999; Jenkinson et al. 1987; Jenkinson, 1990;Jenkinson et al. 1991; Jenkinson et al. 1992; Jenkinson and Coleman, 1994) It needs few inputs and those it needs are easily obtainable. It is an extension of the earlier model described by Jenkinson and Rayner (1977) and by Hart (1984).

A version replacing the monthly time steps by continuous processes has been published by Parshotam (1995). King et al (1997) have incorporated RothC into a much larger model for global C cycling. A comparative study of C turnover models, including RothC-26.3, has recently been published (Smith et al, 1997). RothC-26.3 is designed to run in two modes: forward in which known inputs are used to calculate changes in soil organic matter and inverse , when inputs are calculated from known changes in soil organic matter. RothC-26.3 was originally developed and parameterized to model the turnover of organic C in arable topsoils from the Rothamsted Long Term Field Experiments - hence the name. Later, it was extended to model turnover in grassland and in woodland and to operate in different soils and under different climates. It should be used cautiously on subsoils, soils developed on recent volcanic ash (but see Parshotam et al 1995, Tate et al 1996 and Saggar et al 1996), soils from the tundra and taiga and not at all on soils that are permanently waterlogged.

II. Technical Information

II.1 Executables:

II.2 Source-code:

II.3 Manuals:

II.4 Data:

III. Mathematical Information

III.1 Mathematics

III.2 Quantities

III.2.1 Input

1. Weather data used to run the model
   1. Data type
      • Rainfall - essential
      • Air temperature - essential
      • Evaporation over water - essential
   2. Temporal resolution of weather data
      • Monthly - essential
2. Soil data used to run the model
   • Clay content - desirable
   • Inert carbon composition - desirable
   • Sampling depth, bulk density, % carbon: all used to calculate total carbon insoil layer for input to model.
3. Plant and animal inputs used to run the model
   • Carbon in plant components desirable
   • Crop yield - desirable
4. Land-use and management inputs used to run the model
   • Crop rotation - timing - essential
   • Crop rotation - type - essential
   • Organic manure - timing - essential
   • Organic manure - amount - essential
   • Organic manure - type - essential
   • Residue incorporation - timing - essential
   • Residue incorporation - amount - essential
   • Residue incorporation - type - essential

III.2.2 Output

1. Soil outputs
   • Total carbon
   • Biomass carbon
   • Carbon dioxide
   • As well as total carbon, also carbon content of individual fractions.Radiocarbon content of individual fractions is expressed as a delta 14C value. The radiocarbon content of the biomass carbon can also be derived.

IV. References

Hart PBS (1984) Effects of soil type and past cropping on the nitrogen supplying ability of arable soils.
PhD thesis, University of Reading, UK

Jenkinson DS (1990) The turnover of organic carbon and nitrogen in soil.
Philosophical transactions of the Royal Society, B. 329, 361-368

Jenkinson DS, Adams DE and Wild A (1991) Model estimates of CO₂ emissions from soil in response to global warming.
Nature, 351(6322), 304-306

Jenkinson DS and Coleman K (1994) Calculating the annual input of organic matter to soil from measurements of total organic carbon and radiocarbon.
European Journal of Soil Science, 45, 167-174

Jenkinson DS, Harkness DD, Vance ED, Adams DE and Harrison AF (1992) Calculating net primary production and annual input of organic matter to soil from the amount and radiocarbon content of soil organic matter.
Soil Biology & Biochemistry 24(4), 295-308

Jenkinson DS, Hart PBS, Rayner JH and Parry LC (1987) Modelling the turnover of organic matter in long-term experiments at Rothamsted.
INTECOL Bulletin 15, 1-8

Jenkinson DS and Rayner JH (1977) The turnover of soil organic matter in some of the Rothamsted classical experiments.
Soil Science 123, 298-305

King AW, Post WM and Wullschleger SD (1997) The potential response of terrestial carbon storage to changes in climate and atmospheric CO2.
Climatic Change, 35, 199-227

Parshotam A, Tate KR and Giltrap DJ (1995) Potential effects of climate and land use change on soil carbon and CO2 emissions from New Zealand's indigenous forests and unimproved grasslands.
Weather and climate 15,3-12.

Saggar S, Tate KR, Feltham CF, Childs CW and Parshotam A (1996) Carbon turnover in a range of allophanic soils amended with 14C-labelled glucose.
Soil Biology and Biochemistry 26, 1263-1271

Smith P, Smith JU, Powlson DS, McGill WB, Arah JRM, Chertov OG, Coleman K, Franko U, Frolking S, Jenkinson DS, Jensen LS, Kelly RH, Klein-Gunnewiek, Komarov AS, Li C, Molina JAE, Mueller T, Parton WJ, Thornley JHM & Whitmore AP (1997) A comparison of the performance of nine soil organic matter models using datasets from seven long-term experiments.
Geoderma 81, 153-225

Tate KR, Giltrap DJ, Parshotam A, Hewitt AE, Ross DJ, Kenny GJ and Warrick RA (1996) Impacts of climate change on soils and land systems in New Zealand.
In: Greenhouse: coping with Climate Change (Eds: Bouma WJ, Pearman GI & Manning MR) pp. 190-204, CSIRO Publishing, Melbourne.

V. Further information in the World-Wide-Web

• Rothamsted Carbon Model download page
• GCTE SOMNET Soil Organic Matter Network Database

VI. Additional remarks

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