Variability in soil nitrogen retention across forest, urban, and agricultural land uses
Results/Conclusions: Stable 15N formed within 15 minutes in all land uses, with retention greatest (14% of added 15N) in forest systems, followed by urban and agricultural systems. Stable 15N made up a greater proportion of the retained 15N pool as time increased, in contrast to labile 15N, which decreased over time. The form in which 15N was added impacted partitioning between the soil N pools. When injected as 15NH4+ the stable 15N pool formed within 15 minutes and remained fairly constant over time. For 15NO3- enriched sites stable 15N did not form quickly, and small accumulations were seen in forest and urban systems. Results suggest that the magnitude of the stable 15N pool varies among forest, urban, and agricultural ecosystems, but the rate of change over time is similar among the three land-use types.