CENTURY Soil Organic Matter Model Environment

Technical Documentation

Agroecosystem Version 4.0

Great Plains System Research Unit
Technical Report No. 4

USDA-ARS
Fort Collins Colorado

Alister K. Metherell

Laura A. Harding

C. Vernon Cole

William J. Parton

• ACKNOWLEDGEMENTS

Funding of CENTURY Agroecosystem Version 4.0 was provided by USDA-ARS Global Climate Change Research Program to the CRIS Project "Prediction of Long-term Changes in Carbon Storage and Productivity of U.S. Soils as Affected by Changes in Climate and Management". The New Zealand Ministry of Agriculture and Fisheries provided the support of Alister Metherell for Ph. D. studies. We also acknowledge the support of EPA Project AERL 91-01 to Colorado State University and Michigan State University and NSF grant No. 8605191 to Colorado State University.

We would like to acknowledge those who have contributed to the development of CENTURY. The model was developed as a project of the U.S. National Science Foundation Ecosystem Studies Research Projects "Organic Matter and Nutrient Cycling in Semiarid Agroecosystems" (DEB-7911988) and "Organic C, N, S, and P Formation and Loss from Great Plains Agroecosystems" (BSR-9105281 and BSR- 8406628). The original model was described by Parton, Anderson, Cole, and Stewart (1983), with computer programming done by Vicki Kirchner. Additional support for model enhancement was provided by the Tallgrass Ecosystem Fire project (BSR-82007015), the Central Plains Experimental Range-Long Term Ecological Research project (BSR-8605191), the NASA-EOS project "Carbon Balance in Global Grasslands" (NAGW-2662), and the Agriculture Research Service USDA. Collaboration with scientists involved in international projects such as the Tropical Soil Biology and Fertility (UNESCO- TSBF) Programme and the Scientific Committee On Problems of the Environment (SCOPE) Project on "Effect of climate change on production and decomposition in coniferous forests and grasslands" also was instrumental in the development of CENTURY. Version 3.0, released in April of 1991, continued the development of CENTURY with work done by W.J. Parton and programming by Rebecca McKeown. We also acknowledge Dennis Ojima as the originator of the conceptual framework for the EVENT100 scheduler interface.

The support of William Parton, Dennis Ojima, Rebecca McKeown, and William Pulliam was critical for development of this version of CENTURY.

• APPLICATION OF THE CENTURY MODEL

The CENTURY Model Version 4.0 embodies our best understanding to date of the biogeochemistry of Carbon, Nitrogen, Phosphorus, and Sulphur. The primary purposes of the model are to provide a tool for ecosystem analysis, to test the consistency of data and to evaluate the effects of changes in management and climate on ecosystems. Evolution of the model will continue as our understanding of biogeochemical processes improves. The identification of problem areas where processes are not adequately quantified is key to further developments. Ideally, model application will lead to the identification of needed research and new experimentation to improve understanding.

We value the responses and experiences of our collaborators in using CENTURY and encourage their feedback on problems in the current model formulation, as well as insight and suggestions for future model refinement and enhancement. It would be particularly helpful if users would communicate such feedback informally and where possible share with us documented model applications including manuscripts, papers, procedures, or individual model development.

• DISCLAIMER

Neither the Great Plains System Research Unit - USDA (GPSR) nor Colorado State University (CSU) nor any of their employees make any warranty or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference to any special commercial products, process, or service by tradename, trademark, manufacturer, or otherwise, does not necessarily constitute or imply endorsement, recommendation, or favoring by the GPSR or CSU. The views and opinions of the authors do not necessarily state or reflect those of GPSR or CSU and shall not be used for advertising or product endorsement.

i. TITLE
ii. ACKNOWLEGDEMENTS
iii. APPLICATION OF THE CENTURY MODEL
iv. DISCLAIMER

1. INTRODUCTION

2. CENTURY ENVIRONMENT
2.1. Overview of the CENTURY Environment
2.2. Files
2.3. Units of Major Parameters
2.4. Hardware Requirements for PC Version
2.5. Installation of PC Version
2.6. Version 4.0 Upgrade Information

3. CENTURY MODEL DESCRIPTION
3.1. Introduction
3.2. Soil Organic Matter Submodel
3.3. Water Budget, Leaching, and Soil Temperature
3.4. Nitrogen Submodel
3.5. Phosphorus Submodel
3.6. Sulfur Submodel
3.7. Plant Production Submodels
3.7.1 Grassland/Crop Submodel
3.7.2 Forest Submodel
3.7.3 Savanna Submodel
3.8. Fertilizer
3.9. Irrigation
3.10. Cultivation
3.11. Grazingv 3.12. Fire
3.13. Labeled C Simulation (14C and 13C)
3.14. Enriched CO2 Effects
3.15. Soil Incubation (Microcosms)
3.16. Weather Data
3.17. Event Priority
3.18. Model Parameterization

4. PARAMETERIZATION THROUGH FILE100
4.1. Introduction
4.2. Using FILE100
4.3. Reviewing All Options
4.4. Adding an Option
4.5. Changing an Option
4.6. Changing the .100 File
4.7. Deleting an Option
4.8. Comparing Options
4.9. Generating Weather Statistics
4.10. XXXX.100 Backup File

5. SCHEDULING EVENTS THROUGH EVENT100
5.1. Introduction
5.2. The Concept of Blocks
5.3. Defaults and Old Values
5.4. What EVENT100 Needs
5.5. Using EVENT100
5.6. Explanation of Event Commands
5.7. Explanation of System Commands
5.8. The -i Option: Reading from a Previous Schedule File
5.9. Examples of EVENT100 Sessions

6. EXECUTING CENTURY SIMULATIONS
6.1. Executing the PC VIEW Version
6.2. Executing the PC Stand-Alone Version
6.3. Executing the UNIX Stand-Alone Version
6.4. Using LIST100 with Stand-Alone Versions

7. WELD COUNTY, COLORADO HISTORICAL SCENARIO

8. LITERATURE CITED APPENDICES

Appendix 1. CENTURY Reprints

Appendix 2. Definitions for CENTURY Parameters

• Appendix 2.1. Crop parameters (crop.100)
• Appendix 2.2. Cultivation parameters (cult.100)
• Appendix 2.3. Fertilization parameters (fert.100)
• Appendix 2.4. Fire parameters (fire.100)
• Appendix 2.5. Fixed parameters (fix.100)
• Appendix 2.6. Grazing parameters (graz.100)
• Appendix 2.7. Harvest parameters (harv.100)
• Appendix 2.8. Irrigation parameters (irri.100)
• Appendix 2.9. Organic matter addition parameters (omad.100)
• Appendix 2.10. Tree parameters (tree.100)
• Appendix 2.11. Tree removal parameters (trem.100)
• Appendix 2.12. Site specific parameters (.100)
• Appendix 2.13. Output variables

Appendix 3. Sample Weather File and Atmospheric C14 Label File

• Appendix 3.1. Sample Weather File for Weld County, Colorado
• Appendix 3.2. Sample Atmospheric C14 Label File

Appendix 4. Flow Diagrams for the Subroutines and Model Output Variables

Appendix 5. CENTURY Data Files

• Appendix 5.1. CROP.100 Parameter Values
• Appendix 5.2. CULT.100 Parameter Values
• Appendix 5.3. FERT.100 Parameter Values
• Appendix 5.4. FIRE.100 Parameter Values
• Appendix 5.5. FIX.100 Parameter Values
• Appendix 5.6. GRAZ.100 Parameter Values
• Appendix 5.7. HARV.100 Parameter Values
• Appendix 5.8. IRRI.100 Parameter Values
• Appendix 5.9. OMAD.100 Parameter Values
• Appendix 5.10. TREE.100 Parameter Values
• Appendix 5.11. TREM.100 Parameter Values
• Appendix 5.12. Parameter Values

Appendix 6. Addendum

CENTURY Soil Orgainc Matter Model Environment Report any problems with this document via email century@nrel.colostate.edu

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