Soil cores were harvested at the end of preincubation
period and thereafter every two weeks in
order to compare changes over time. Total carbon (TC)
was detected by a LECO 2000 CN analyzer. The
particle size distribution was determined by the
Pipette method (Gee and Bauder, 1986). Soil pH was
measured in 1:2.5 (soil/0.01 M CaCl
2
) using glass
electrode pH meters. Soil mineral N (NH4
+
and NO3
-
)
was extracted in a 1 mol/l KCl solution (soil/liquid
ratio 1:5 w/w) as reported by Keeney and Nelson,
(1982). The filtrates were then analyzed on an
automated flow injection analysis (Brann en Luebbe
TrAAcs 800 Auto analyzer).
Net nitrogen nitrification (NNN) m