Root traits of contrasting crop genotypes and their influence on soil biogeochemical cycles

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The long-term objective of my research program is to investigate the link between plant roots and soil biogeochemical cycles. Roots directly interact with the soil to alter the physical and biochemical environment to support plant growth. However, our knowledge on how roots indirectly affect soil processes vital to agroecosystem functioning beyond crop production, including nutrient cycling, soil organic matter formation, and structural stability, is relatively limited. Addressing the gap in our knowledge on root interactions with soil processes is especially important in agricultural systems as farmers across Canada are abandoning monocultures for increasingly diverse crop rotations due to changing global market and climate conditions. Predicting the effects of growing a diversity of different crop genotypes in our agricultural systems on ecosystem function requires better characterization of their root traits and how those traits affect soil biogeochemical cycles. ***My program will take a plant traits based approach to understand root influences on nutrient cycles important to plant productivity as well as on carbon dynamics that affect soil quality and global climate. The specific objectives of my research program are to investigate the influence of root chemical and structural traits and their interactions on: (1) root decomposition rates and soil phosphorus and nitrogen bioavailability; (2) the fate of root-derived carbon in soil aggregates and the soil microbial community; and (3) the spatial profile of rhizosphere chemistry and microbial community structure. I will use crop species known a priori to differ markedly in the structure of their root systems and cultivars that have been genetically selected to vary in plant tissue chemistry throughout a series of studies that examine the root-soil interface with increasing complexity over the course of the five-year program. Stable isotope labeling of plants will be used to investigate the fate of root-derived inputs in soil, molecular biological techniques will characterize root-driven structuring of soil microbial communities, and novel techniques in imaging extracellular enzyme activities will be used to elucidate the influence of roots on potential nutrient bioavailability. Understanding the microbial processing of structurally and chemically diverse root inputs will improve our predictions of plant nutrient supply and the fate of carbon in the soil under changing agronomic and climate conditions. By taking a trait-based approach to understanding root influences on soil biogeochemical processes, this work can inform the design of cropping systems that exploit desirable root traits to enhance crop productivity and ecosystem function.**