2.3 Effect of soil microbial biomass carbon and nitrogen on
enzyme activity unde different water and fertilizer optimal management
The Mantel analysis method was used to obtain correlation and
explanation values for the relationship between soil microbial biomass
carbon and nitrogen and soil enzyme activity under different water and
fertilizer optimal management conditions. It could be seen from Fig.2a
that the Mantel significant values of soil acid phosphatase, catalase,
and microbial carbon were the smallest (Mantel’s p<0.01). Soil
sucrase, acid phosphatase, catalase, and microbial nitrogen had the
least Mantel’s p<0.01, while sucrase (Sue) had less than 0.05,
and urease had less than 0.05. The maximum interpretation values of soil
microbial biomass C and N by acid phosphatase and catalase (Mantel’s
r≥0.5) indicated that soil microbial biomass C and N content determined
soil acid phosphatase and catalase activities, and the maximum
interpretation value of soil microbial biomass N by sucrase (Mantel’s
r≥0.5) indicated that soil microbial biomass N content determined soil
sucrase (Sue) activity. However, Mantel significant and interpreted
values of urease and soil microbial biomass carbon and nitrogen were
(Mantel’s p<0.05, Mantel’s r = 0.25~0.5), which were
important factors affecting microbial biomass carbon and nitrogen. The
results in Fig.2b showed that soil enzyme activities and soil microbial
biomass C and N had different degrees of correlation. The correlation
coefficient of soil acid phosphatase and catalase activity to soil
microbial biomass carbon and nitrogen were between 0.90 and 1.00,
indicating that there was a very significant positive correlation
between soil acid phosphatase and catalase activities and soil microbial
biomass carbon and nitrogen content (p<0.01), which was
consistent with that results in Fig.2a. The correlation coefficient of
urease and sucrase activities to soil microbial biomass c and n were
0.80~0.95, indicating that urease and sucrase activities had a
significant positive correlation with soil microbial biomass c and n
(p<0.05).