3.5. Microbial biomass carbon (MB-C)
The tillage treatments reduced soil MB-C significantly, but the
reduction was the highest in the frequent till and the lowest in the
long term zero till treatment (Table 3 and Fig. 2e). The seasons also
affected the MB-C significantly (Table 3). Across the seasons, it was
the highest during the post-wet season and the lowest during the
wet season in all tillage treatments (Table 4). MB-C was positively
correlated with the net soil N mineralization rate (r = 0.746–0.859,
P < 0.01–0.001) and the net nitrification rate (r = 0.750–0.906,
P < 0.01–0.001) in all tillage treatments. The MB-C, being a labile
fraction, was positively correlated to the SOC (r = 0.961, P < 0.01)
across the tillage treatments. MB-C/SOC ratio was the highest
(0.06) in the short term zero till and the lowest (0.03) in the long
term zero till treatment.