net N mineralization rate, microbial community structure, and extracellular enzyme activity. The second part was air-dried for determination of soil pH, soil organic carbon, total soil nitrogen, and extractable cations (Al3+, Ca2+, Mg2+, and Na+). A 20-g subsample of moist soil was oven-dried at 105 °C for 24 h to determine soil moisture. Soil pH was measured in a 1:2.5 (soil:water) suspension. Soil organic carbon content was determined using the dichromate oxidation method. Total soil nitrogen was determined by the micro-Kjeldahl digestion, followed by colorimetric determination on a 2300 Kjeltec Analyzer Unit.