Towards assessing climate sensitivity of microbial processes and its effect on greenhouse gas fluxes in subtropical pastures

Towards assessing climate sensitivity of microbial processes and its effect on greenhouse gas fluxes in subtropical pastures

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  Stefan Gerber, SaroopSandhu, Dipti Rai, Kanika Inglett, Patrick Inglett, Ryan Penton, and Maria Silveira [email protected] Towards assessing climate sensitivity of microbial processes and its effect on greenhouse gas fluxes in subtropical pastures
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  Site location: USDA-LTAR- UF IFAS Range and Cattle Research and Education Center, Ona Florida
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  • Characterize thesoil microbial community across different management practices and measure the corresponding greenhouse gas fluxes. • Determine the adaptation and acclimation of the soil microbial community climate change. • Improve a soil greenhouse gas emission model to predict greenhouse gas emissions under global change scenarios Project start was August, 2016 Project Objectives
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  Consistently managed sites
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  Native Rangeland Improved Pasture
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  Preliminary Laboratory Analyses
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  Initial Soil Characterization
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  • Management hasno impact on bulk density of soil. However, bulk density is significantly different for soil horizons. • Bh horizon has lower bulk density compared to E2 probably be due to more organic carbon present. • Soil pH is higher in managed grassland might be due to the addition of manure from cattle grazing. • Also, soil pH increases with depth. Preliminary results
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  • Management hasno impact on moisture content of soil. However, moisture content is significantly different for soil horizons. • Managed grassland has higher aerobic respiration rate which may be due to extra nitrogen source available by manure and chemical fertilizer additions. Preliminary results
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  • Enzymes –β-glucosidase –Cellobiose Dehydrogenase –N-Acetyl-β-DGlucosaminidase –Leucyl aminopeptidase • Microbial biomass carbon and nitrogen • Total carbon and nitrogen • Anaerobic respiration • Isotope analysis • Carbon fractions Analyses in progress
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  Future steps Adressing MicrobialResponse • 3 Key responses - Kinetic response (e.g. Vmax) - fast - molecular analysis to address functional (gene expressions) slower - community response – slowest • Incorporation of key responses into a new microbial-based decomposition and greenhouse gas production module in DNDC
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  Conceptual/Numerical Model Functional and communityresponse Kinetic Response Sihi et al., 2016, Biogeoscience
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  Expect different climateresponse Sihi et al., 2016
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  Laboratory experiment andfield data – Assessing of CO2, N2O fluxes In the field: take advantage of seasonal and interannual cycle
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  We’ll go outsome more!