Reference number : GC-2017-Q1-02936, amendment number : , agreement type : G, recipient legal name : Walley, Frances (University of Saskatchewan), recipient country : CA, recipient province : nan, recipient city : Saskatchewan, recipient postal code : nan, program name english : Discovery Grants Program - Individual, program name french : Programme de subventions à la découverte - individuelles, program purpose english : Nitrogen (N) is a key ecosystem nutrient controlling net primary production in both agricultural and unmanaged ecosystems. During microbial decomposition of soil organic matter, bioavailable inorganic N is released to the environment, with implications for agricultural and environmental sustainability. Despite the importance of this nutrient, our understanding of the many factors controlling N-cycling processes, including the protection (and release) of N from soil organic matter remains incomplete. It has long been recognized that calcium (Ca) plays a role in the protection of soil organic N through ionic associations with soil organic matter (i.e., Ca bridging) and encapsulation of organic matter in Ca minerals precipitated from the soil solution. These physical protection mechanisms typically are attributed to abiotic processes, whereby Ca reacts with organic matter as a consequence of changing soil conditions, such as the wetting and drying cycles that influence Ca solubilization in the soil solution. What remains largely unexplored, however, is the contribution of biotic processes&mdash;specifically the action of soil microorganisms&mdash;to the precipitation of Ca minerals such as calcite, and the consequent protection of soil organic N. Although the role of microbes in the precipitation of calcite has been investigated in a range of aquatic and terrestrial environments, the significance and contribution of microbially-induced precipitation of calcite (MICP) to the physical protection of soil organic N has not been addressed. It has been hypothesized that MICP occurs in Ca-rich environments as a mechanism to protect microbial cells from self-calcification. Moreover, MICP is often associated with the enhanced production of extracellular polymeric substances (EPS) by these same microbes, also as a protection mechanism in Ca-saturated environments. The proposed program explores the possibility that MICP together with the associated production of EPS plays a significant role in soil aggregate stabilization and thus soil organic N protection in Ca-rich soil environments typical of the Canadian prairies. Cutting edge techniques, such as synchrotron-based examinations of soil microaggregate structures, together with molecular identification of the microorganisms responsible for aggregation, will be used to shed light on physical processes at the microscale that contribute to N bioavailability at the macroscale. Ultimately, we need to understand microscale processes before we can successfully develop macroscale strategies to manage N in agroecosystems., program purpose french : Nitrogen (N) is a key ecosystem nutrient controlling net primary production in both agricultural and unmanaged ecosystems. During microbial decomposition of soil organic matter, bioavailable inorganic N is released to the environment, with implications for agricultural and environmental sustainability. Despite the importance of this nutrient, our understanding of the many factors controlling N-cycling processes, including the protection (and release) of N from soil organic matter remains incomplete. It has long been recognized that calcium (Ca) plays a role in the protection of soil organic N through ionic associations with soil organic matter (i.e., Ca bridging) and encapsulation of organic matter in Ca minerals precipitated from the soil solution. These physical protection mechanisms typically are attributed to abiotic processes, whereby Ca reacts with organic matter as a consequence of changing soil conditions, such as the wetting and drying cycles that influence Ca solubilization in the soil solution. What remains largely unexplored, however, is the contribution of biotic processes&mdash;specifically the action of soil microorganisms&mdash;to the precipitation of Ca minerals such as calcite, and the consequent protection of soil organic N. Although the role of microbes in the precipitation of calcite has been investigated in a range of aquatic and terrestrial environments, the significance and contribution of microbially-induced precipitation of calcite (MICP) to the physical protection of soil organic N has not been addressed. It has been hypothesized that MICP occurs in Ca-rich environments as a mechanism to protect microbial cells from self-calcification. Moreover, MICP is often associated with the enhanced production of extracellular polymeric substances (EPS) by these same microbes, also as a protection mechanism in Ca-saturated environments. The proposed program explores the possibility that MICP together with the associated production of EPS plays a significant role in soil aggregate stabilization and thus soil organic N protection in Ca-rich soil environments typical of the Canadian prairies. Cutting edge techniques, such as synchrotron-based examinations of soil microaggregate structures, together with molecular identification of the microorganisms responsible for aggregation, will be used to shed light on physical processes at the microscale that contribute to N bioavailability at the macroscale. Ultimately, we need to understand microscale processes before we can successfully develop macroscale strategies to manage N in agroecosystems., agreement title english : Microscale controls on soil organic matter stabilization and impacts on nitrogen cycling in Canadian prairie agroecosystems, agreement title french : Microscale controls on soil organic matter stabilization and impacts on nitrogen cycling in Canadian prairie agroecosystems, agreement number : RGPIN, agreement value : 135000.0, agreement start date : 2017-05-10, agreement end date : nan, description english : nan, description french : nan, expected results english : nan, expected results french : nan, additional information english : Grant or Award spanning more than one fiscal year. (2017-2018 to 2022-2023), additional information french : Subvention ou bourse octroyée s'appliquant à plus d'un exercice financier. (2017-2018 à 2022-2023), owner organization : nserc-crsng, owner organization title : Natural Sciences and Engineering Research Council of Canada | Conseil de recherches en sciences naturelles et en génie du Canada