Management approaches have considerable influence on soil organic matter (SOM) dynamics. A four-year study was designed to evaluate the SOM dynamics of organic, reduced-input, and conventional approaches in cash-crop and beef-calf forage production in high plains of Wyoming. This study constitutes a part of an interdisciplinary long-term project evaluating economic and environmental sustainability of organic, reduced input and conventional production approaches in crop-range-livestock farming. Six production systems (3 approaches x 2 systems) on four replicated plots were established at James C. Hageman Sustainable Agriculture Research & Extension Center near Lingle, Wyoming, in 2009. Soil samples were collected in spring, early and late summer, and fall seasons of 2009 and 2010, and were analyzed for soil organic carbon, total nitrogen, mineral nitrogen, and potentially mineralizable carbon and nitrogen. Result from first and second year revealed that carbon and nitrogen parameters have started responding to the management approaches applied in the plots. Further investigation will lead to better understanding of differences among these management approaches in high dry condition of Wyoming crop-range-livestock farming.