Microbe-mineral interactions and the fate of soil carbon

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Information about Microbe-mineral interactions and the fate of soil carbon

Published on December 23, 2016

Author: NIFA_IBCE

Source: slideshare.net

1. Microbe-mineral interactions and the fate of soil carbon Courtney Creamer, Andrea Foster, Corey Lawrence, Jack McFarland, Marjorie Schulz, Mark Waldrop ccreamer@usgs.gov 2014-67003-22043

2. Importance of microbes & minerals for stable carbon (C) formation Cotrufo et al., 2015 Nature Geoscience Underlying research question: How does soil mineralogy and microbial community structure influence the stability of C with different chemistries across micro to regional scales?

3. Activities span µm to km scales Activity 1: Raman spectroscopy development Activity 2: Sterile and non- sterile experiments Activity 3: Soil mesocosms Activity 4: Climo-chronosequences Repeat Create microbial residues Quantify released residues Add plant- derived DOC Activity 5: Reactive transport modeling

4. Activities span µm to km scales Activity 1: Raman spectroscopy development Activity 2: Sterile and non- sterile experiments Activity 4: Climo-chronosequences 13C organics

5. Controls on C stabilization • Abiotic: Sorption, aggregation • Biotic: Efficiency of microbial processing • Influenced by C chemistry, microbes, mineralogy, soil depth

6. Raman spectroscopy development Non-destructive in-situ quantification of: Microbial 13C assimilation Carbon chemistry and spatial distribution

7. X X X X X X 13C CO2 3 weeks Does mineralogy affect stabilization of dead microbial residues? X X

8. Cumulative respiration 7.3% 0.73% Anabolism 94% 13C 4% 13C Dead microbes are stabilized on highly sorptive minerals

9. C stabilization affected by mineral and life status Aluminum hydroxide: Feldspar: Live E. coli Dead 13C Arthrobacter Live and dead 74% 58% 52% 0.8%

10. C stabilization affected by mineral and life status Aluminum hydroxide: Feldspar: Live E. coli Dead 13C Arthrobacter Live and dead 52% 0.8% 25% 10%Live microbes stabilized residues Live microbes destabilized sorbed residues

11. What is the fate of added C with depth? • Glucose – Efficient biotic processing, low sorption • Oxalate – Inefficient processing, high sorption CarbonC/N % Clay SSA m2∙g-1 Soil specific surface area (SSA) and % clay

12. Photo: Corey Lawrence Construction of in situ incubation units

13. Recovered in soil (%) Oxalate-derived C not stabilized long-term A A/B B 100806040200

14. Recovered in soil (%) Glucose-derived C stabilized through profile A A/B B 100806040200

15. Vulnerability of stabilized C with depth -27% -53% -81% A A/B B 100806040200 Recovered in soil (%)

16. Conclusions: • Efficient biotic processing is an important driver of the stabilization of added C – Live microbes > dead residues – Glucose > oxalic acid • No simple rule for C stabilization on minerals – Microbes can destabilize or stabilize C depending on mineralogy – Deep carbon was vulnerable to oxidation

17. Future directions Activity 1: Raman spectroscopy development Activity 2: Sterile and non- sterile experiments Activity 3: Soil mesocosms Activity 4: Climo-chronosequences Repeat Create microbial residues Quantify released residues Add plant- derived DOC Activity 5: Reactive transport modeling

18. Future directions Activity 1: Raman spectroscopy development Activity 2: Sterile and non- sterile experiments Activity 3: Soil mesocosms Activity 4: Climo-chronosequences Repeat Create microbial residues Quantify released residues Add plant- derived DOC Activity 5: Reactive transport modeling • Raman applications: • Generate parameters for microbially explicit models • Extrapolation to larger regions • Mechanisms of C stabilization and loss • Applied questions on land use change • Increase soil carbon and understanding vulnerability

19. Thank you! Tim Hyland and the Staff at Wilder Ranch State Park USGS Colleagues: Marjorie Schulz Sabrina Sevilgen Sharon Mehlman Andrea Foster Funding: USDA (2014-67003-22043)

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