Fig. 3. Isotopic character of N2O in labeled jars at the end of incubations (with ambient N2O for reference). Filled and open symbols represent long-wet and short-wet treatments, respectively; shape corresponds to replicate. Points lying on or near the equilibrium curve indicate samples approximately in isotopic equilibrium with respect to 15N distribution among molecular masses, suggesting derivation from an isotopically uniform pool. Higher effective enrichment of successional soils relative to cropped soils reflects a smaller contribution from native soil NO-3.
