ASSESSING THE IMPORTANCE OF FREE-LIVING NITROGEN FIXATION IN ORGANIC SYSTEMS

Goals:1. Advance scientific understanding of asymbiotic dinitrogen fixation in organic production systems.2. Improve or maintain soil health, sustainability, and productivity in organic production systems.Objectives:1. Modify and optimize the 15N2 assay method of Smercina et al. (2019) for estimating free-living N2 fixation (FLNF) in rhizospheric soil, with (potential) or without (baseline) the use of a C cocktail, relative to:1a. Incubation period; and1b. C cocktail composition.2. Compare different phases of organic rotation regarding:2a. Diazotrophic abundance and diversity using targeted genes for N2 fixation, nitrification, denitrification, and mineralization; and2b. Functional capacity of FLNF assayed using 15N2.3. Ascertain the potential of liming and the use of gypsum for increasing FLNF under organic management with respect to:3a. The abundance and composition of functional genes targeting N-cycle genes;3b. 15N2-measurements of potential and baseline (no C cocktail) FLNF; and3c. Cereal yields and N accumulation.