5 Conclusion
This
study demonstrated that 20 years of IM practice using MCM (combined
inorganic fertilizer and manure application) in Moso bamboo
plantation enhanced the content of SOC and available soil N, P, and K,
although fluctuations were observed. Soil pH was generally stable with
values between 5.0 and 5.5, indicating little acidification occurred.
Soil CO2 and N2 fixing bacteria
responded strongly to IM strongly in the short term and then gradually
recovered over time, indicating an inherent resilience. The abundance of
CO2-fixing bacteria eventually returned to their
original levels but their communities did not. In contrast, the
communities of N2-fixing bacteria recovered to their
initial state while their abundances did over after 20 years of IM. The
diversity of both groups of bacteria had a turning point after 10 years
of IM, as reflected by higher values for Shannon and Evenness indices
but lower values for the Simpson index compared with the remaining
treatments. Both CO2 and N2 fixation
bacterial groups had similar dominant species, but these differed in
their relative abundances among the treatments and also exhibited
different patterns in response to IM duration. The results indicated
that relationships between potential environmental drivers and measures
of abundance and community composition for both CO2- and
N2- fixing bacteria are complex. Nevertheless, IM
practice using MCM in Moso bamboo plantation appeared to have an
overall positive effect on these bacterial groups as well as on
associated soil properties.