1. Coastal soils are prone to salinity intrusion. However, the response and resiliency of soil microbial communities to this environmental perturbation is a complex interplay of hydrobiogeochemical processes. I am evaluating the impact of salinity intrusion on microbe-mediated biogeochemistry of soil carbon and furthering conceptual understanding of coupled feedbacks on the soil microbial communities themselves.

Coastal inundation dynamics impact carbon biogeochemistry and soil microbial ecology (Sengupta et al., 2019)

2. The evolution of a fertile soil, either from parent rock material or from a degraded system, is a function of abiotic and biotic processes with microbe-mediated processes occurring at fine scales of pores and aggregates, and impacting processes over multiple scales of space and time.

I am investigating spatiotemporal heterogeneity of microbial community structure and function in basalt soils. My work focuses on understanding effects of coupled hydrogeochemical forcings on microbial community composition and function, and how this affects organic carbon sequestration and cycling in incipient soil systems. This work has pushed the boundaries of identifying incipient soil systems capable of harboring heterogeneous microbial life and influencing early soil ecology. Results thus far reveal the presence of significant heterogeneity in predicted functions and ecologically deterministic shifts in community composition in a homogeneous soil system.

Interestingly, community diversity was found to be strongly correlated with soil depth, irrespective of whether sampling was carried out in  2m x 0.5m or 30m x 11m lysimeters housed at Landscape Evolution Observatory, Biosphere 2. This comparative assessment is unique to the question of scaling in microbial ecology studies, where spatial variability was evaluated while controlling for other edaphic variables (including parent material, temperature, precipitation, and topography). The evidence of conserved spatial trends in microbial community composition in the incipient basalt soil will allow predictive estimates to be developed when investigating microbial community movement and establishment in landscapes.

      2m x 0.5 m x 1m soil lysimeter, miniLEO         

                                          30 m x 11m x 1m soil lysimeter, LEO

3. Fertile top soil is being lost at unprecedented rates. FAO estiamtes that about 60 years of arable land is left globally if we continue to use our soils in the current manner to grow food and fiber. With this problem in mind, I am evaluating the capacity of marginal soils to support plant growth. While not all marginal soils can be used for food production, the ability to vegetate marginal soils will improve the overall quality of any ecosystem. Particularly, I am researching the efficacy of native plants to grow and sustain in marginal soils. Going back in history and using native knowledge stands to preserve culture heritage as well.

Greenhouse experiment evaluating ability of incipient soil to support growth of plansts native Southwestern Arizona

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