Net N mineralization was calculated as the change in total inorganic N content from the start until the end of incubation. The changes in NH4+−N and NO3−−N concentrations over one month were obtained by subtracting the initial concentration from the corresponding final concentration, and the resultant values are referred to as net ammonification and net nitrification rates. Net N mineralization was calculated as the sum of ammonification and nitrification rates over one month (Evans et al., 2001)