*2.3. Inorganic Soil Nitrogen Production*

We defined inorganic N production as the rates of production of NH4-N (mineralization) and NO3-N (nitrification). Mineralization is the microbial process whereby organic N is converted to mineral N, while nitrification is the process whereby ammonium N is converted to NO3 −N by aerobic bacteria. Both soil net mineralization and nitrification rates were determined after methods described by Raciti et al. [15]. Briefly, 10 g field moist soil was incubated in Erlenmeyer flasks for 14 days with a 12:12 light/dark cycle and at lab ambient temperature (approximately 22 ◦C). Flasks were loosely covered with parafilm, and DI water (<2 mL) was periodically added to the soils as needed to maintain field capacity moisture conditions during the incubation. At the conclusion of the incubation period, soils were extracted with 50 mL 2 M KCl and analyzed for NO3 − and NH4 <sup>+</sup> as above. A separate set of flasks and soils was likewise analyzed but without incubation and taken as the time zero, or initial, measurements. At the conclusion of the incubation period, net mineralization was calculated as the accumulation of total inorganic N (NH4 <sup>+</sup> + NO3 −) and nitrification was calculated as the accumulation of NO3 −. Results were expressed in mg N kg soil−<sup>1</sup> day−1, after using the initial gravimetric soil water content to base calculations on the equivalent dry mass of soil in each flask. Results were examined for each landscape patch by depth as well as on a whole-core basis [15].
