Nitrogen is one of the most important plant nutrients and often its availability is the limiting factor for primary production.  Nitrogen enters an ecosystem from the atmosphere and can be cycled via many different pathways before it is either stored in the soil, returned to the atmosphere or leached into ground water.  Recent realizations that most nitrogen stored in soil is in labile, organic forms rather than recalcitrant compounds have led to a re-evaluation of how it is sequestered for extended time periods.  The long-term (centuries to millennia) storage of nitrogen in soils is influenced by many interacting factors.  Adsorption to mineral particles, physical protection and microbial processing are now thought to be the primary controls governing the transfer of nitrogen to the long-term storage pool.  The rate of durable nitrogen storage is an important term in critical loads equations, and better understanding of the factors influencing it will provide more accurate estimates for this term.  This new understanding can also have important implications for models of nitrogen cycling as well as policies governing anthropogenic emissions.