Nitrogen is an essential element of agricultural productivity, but it has numerous mechanisms and opportunities for loss to the environment, which can threaten environmental quality.  Stabilization of N in soil can be achieved through its direct coupling with C in soil organic matter.  This presentation describes recent research on soil C and N changes under various pasture management systems.  Carbon and N cycle through different fractions of organic matter – particulate, microbial biomass, and aggregate-associated.  The influence of these different fractions on conservation of C and N in soil will be explored.