2007 Annual Report 1a.Objectives (from AD-416) The objective is to study the roles of arbuscular mycorrhizal (AM) fungi in carbon sequestration in conventional, chemical-based, and organic agricultural systems and the contribution of an enhanced AM fungus population upon the composition and nutritional quality of food. 1b.Approach (from AD-416) Results of The Rodale Institute Experimental Farm's Farming Systems Trial has showed the potential of organic farming to sequester large amounts of carbon in the soil relative to the minimal net carbon holding capacity of soils farmed via conventional methods. ERRC scientists will collaborate to test the hypothesis that the production of glomalin and hyphal biomass by the large population of AM fungi in organically farmed soils contributes significantly to the observed carbon sequestration in these soils. 3.Progress Report This report serves to document research progress under Cooperative Agreement 58-1035-5-524 with The Rodale Institute. Additional details of this research can be found in the report of the parent project 1935-12000-010-00D: Development of efficient and practical methods for producing arbuscular mycorrhizal fungi. This project utilizes the resources of the Rodale Farming Systems Trial to study the contribution of glomalin (a carbon-containing compound believed to have an important role in stabilizing soil aggregates and to be very resistant to degradation) deposited by arbuscular mycorrhizal [AM] fungi to the observed increase in soil organic matter in organically-farmed soils relative to conventionally-farmed soils. This research contributes to Milestones of Objective 3 of the parent project. Field sampling for this experiment began in autumn 2006. Results available to date show higher levels of organic matter and soil carbon to a depth of 30 cm in the organically than conventionally farmed soils. Populations of AM fungus propagules were distributed in a similar pattern as soil organic matter both among farming systems and through the soil profile, indicating at least a correlation between levels of AM fungi and carbon sequestration in agricultural soils. Confirmation of this hypothesis awaits the data on glomalin levels in the soil, currently being conducted by K. Nichols (ARS, Mandan, ND), and another round of sampling in the autumn of 2007. Activities are monitored by the ADODR via site visits and active participation in the project. (NP 202 Action Plan component Understanding and Managing Soil Biology and Rhizosphere Ecology, Performance Measures in the ARS Strategic Plan, 5.2.2 and 5.4.2).