Understanding belowground carbon (C) and nitrogen (N) dynamics in differently managed ecosystems is essential for accurate modeling of C sequestration. A field project was initiated in 2004 with three different ecosystems: restored tallgrass prairie (PR) (Andropogon gerardii and Sorghastrum nutans), tilled (CT) grain sorghum (Sorghum bicolor), and no-till (NT) grain sorghum. The field had previously been under tilled wheat (Triticum aestivum) production. The objectives were to study C and N cycling as affected by level of disturbance and by altering the flow of C and N in the plant-soil system. Flow of C from plants to soil was altered by suppression of arbuscular mycorrhizal (AM) fungi. Measurements included soil C and N, soil CO₂ flux, soil aggregation, and soil biological parameters. Changes in soil C levels were also obtained by measuring incorporation of new C ₄ plant C into the C<sub>3</sub labeled soil organic matter. Soil biology measures included % AM fungal root colonization, microbial biomass, and biotic community composition. Topsin (thiophanate-methyl) or phosphorus (P) additions significantly decreased the % AM fungal root colonization in PR and NT by 50%, but did not affect the low levels of root colonization in CT. After two growing seasons, microbial biomass C was similar in each ecosystem, with an average value of 287 mg biomass C g^-1 soil. Ecosystem management resulted in significant changes in microbial community composition. The fungal biomass was approximately 75% higher in PR and NT, as compared to CT. Management-induced changes in soil biology may help explain changes in C flux that foster enhanced C sequestration in less disturbed ecosystems such as no-till or grass plantings. Soil C and N levels following the 2006 growing season, soil aggregation, along with soil CO₂ flux will be discussed.