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Beth Drewniak

Soil organic carbon response to harvested crops: a comparison between biogeochemistry model versions. Beth Drewniak. Background/Motivation. CLM4.5 – harvest puts grain into litter pools Microbes = Happy Farmers = Sad But, removing grain has a big impact on the carbon cycle.

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Beth Drewniak

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  1. Soil organic carbon response to harvested crops: a comparison between biogeochemistry model versions Beth Drewniak

  2. Background/Motivation • CLM4.5 – harvest puts grain into litter pools • Microbes = Happy • Farmers = Sad • But, removing grain has a big impact on the carbon cycle http://www.sipcamadvanblog.com/wp-content/uploads/2013/03/corn_harvest.jpg CLM Working Group Meeting, February 24-27, 2014

  3. First: Calculate Yields • Calculate grain yield (adapted from Agro-IBIS): Yield = grainc * fyield * convfact / cgrain • grainc = grain carbon (g/m2) • fyield = adjustment factor for portion of grain that is actually harvested • convfact = conversion to get from g/m2 to bu/acre • cgrain = amount of carbon in grain (0.45) CLM Working Group Meeting, February 24-27, 2014

  4. Harvesting Grain • Grain carbon and nitrogen pushed into product pool • Decays over 1-yr • Can be coupled to atmosphere as respiration • Option to put leaves and stems into product pool, currently not used CLM Working Group Meeting, February 24-27, 2014

  5. Yields when crops are harvested CLM Working Group Meeting, February 24-27, 2014

  6. PTCLM: Bondville, ILAmeriflux siteBGC vs. CN Photo Courtesy of David Cook CLM Working Group Meeting, February 24-27, 2014

  7. Gross Primary Productivity at Bondville, ILunder a corn-soybean rotation • 1997 1999 2001 2003 2005 2007 CLM Working Group Meeting, February 24-27, 2014

  8. Net Ecosystem Exchange at Bondville, IL • 1997 1999 2001 2003 2005 2007 CLM Working Group Meeting, February 24-27, 2014

  9. Corn at Bondville, IL CLM Working Group Meeting, February 24-27, 2014

  10. Soybean at Bondville, IL CLM Working Group Meeting, February 24-27, 2014

  11. What about Soil Carbon?…and other crazy plots CLM Working Group Meeting, February 24-27, 2014

  12. At Bondville, IL Year CLM Working Group Meeting, February 24-27, 2014

  13. Crazy corn yields – increasing, and huge variabilityOther crops are OK Year CLM Working Group Meeting, February 24-27, 2014

  14. A global perspective CLM Working Group Meeting, February 24-27, 2014

  15. Conclusions • Harvest does have an effect on plant productivity • BGC works great for corn, CN works better for soybean • Harvest results in a decrease in SOC for CN, but not for BGC • Increases in SOC result in increasing yield • Model needs to be properly spun up with crops CLM Working Group Meeting, February 24-27, 2014

  16. Future Directions • CSI (Corn Scenario Investigation) to resolve the corn yield • Run with other atmospheric forcing data? • Calibrate parameters – in progress for soybean • Start testing residue harvest • Incorporate other management practices CLM Working Group Meeting, February 24-27, 2014

  17. Thanks Acknowledgements This work was supported by the Office of Biological and Environmental Research, U.S. Department of Energy, under Contract DE-AC02-06CH11357. Numerical simulations were performed with resources provided by “Fusion,” a 320-node computing cluster operated by the Laboratory Computing Resource Center at Argonne National Laboratory and the National Energy Research Scientific Computing Center, supported by the Office of Science and US Department of Energy Contract No. DE-AC02-05CH11231. CLM Working Group Meeting, February 24-27, 2014

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