The lab's current research fits into 4 main themes.
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Interactions between soil moisture and organic carbon |
Related publications and products: Shabtai et al. 2022, Das et al., 2018
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Soil moisture controls soil organic carbon turnover and storage by regulating biotic activity, solute transport, gaseous exchange, and mineral weathering. However, long-term differences in moisture are not well understood, and may either stimulate or decrease SOC losses by changes to vegetation, mineral composition, carbon chemical composition and resultant organo-mineral interactions. As climate change is expected to drastically alter soil moisture conditions globally, a better understanding of the effects of soil moisture on soil organic carbon is needed. By studying a long-term soil moisture gradient we found that greater moisture enhanced microbial transformation of plant inputs and their interactions with reactive mineral surfaces, which resulted in soil organic carbon accumulation.
Currently, we are exploring how long-term soil moisture and soil moisture fluctuations, perceived by microbes as water potential, impacts microbial carbon use efficiency (CUE) and conversion of biomass into the mineral association organic matter (MAOM). Preliminary results using stable isotope tracing experiments show that extreme moisture values decrease CUE and the amount of new MAOM-C. |
Plant root exudation as a carbon input and a driver of biogeochemical cycling |
Related publications and products: EMSL Exploratory Research, Talk 2023 Tri-Societies meeting
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Plant root exudates constitute a significant source of soil organic carbon. They also activate microbial activity and community shifts, impact plant-water relations, and drive elemental cycling within the rhizosphere. However, exudates are stealthy - they are rapidly consumed by microbes and adsorb to mineral surfaces - making it a challenge to collect them, and to study their composition, and transformation. We are using several approaches to sample root exudates, such as with micro dialysis probes, or in hydroponic setups and analyze their molecular composition. We also pulse-label plants with 13-C CO2 and trace the labeled C as it cycles between soil C pools. We then investigate how exudates interact with mineral surfaces using (micro)spectroscopy to piece together a fuller picture of how exudates drive C cycling in the rhizosphere.
Another challenge is determining how plant growing conditions (e.g., drought stress) affect exudation patterns and rhizosphere processes. We are currently collaborating with EMSL to test the hypotheses that under drought exudation rate and composition are coupled to water use strategy. Cutting edge analytical techniques such as laser ablation-IRMS and MALDI-FTICR will be combined with isotope labeling and tracing to explore these exciting questions. |
Evaluating calcium and calcium amendments as tools for managing soil organic carbon |
Related publications and products: Shabtai et al. 2023,
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Agricultural benefits of organic amendments |
Related publications and products: CT DoAG Specialty Crops Block Grant 2024-2026.
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Sustainable management of soil and soil organic matter should aim to achieve agricultural and environmental benefits. As part of this project we will evaluate the use of organic amendments to enhance soil water storage, increase soil carbon stocks, and reduce plant stress during drought conditions.
We will ask questions about the mechanisms through which organic amendments alter the soil water retention properties, and do these changes translate to greater plant available water, and reduced plant stress. We are looking for undergrad research assistants! See the opportunities page to get involved in this project! |