period. However, the triple-fertili

period. However, the triple-fertilizer treatments usually had higher AWCD values than other treatments,
indicating that these three treatments had a higher microbial activity. The AWCD value at 72-h was
often used to describe the difference of soil microbial activities among the different treatments. In
this experiment, the AWCD value at 72-h increased in the following order for the different treatments:
control < NK < PK < NP < NPK < NPK2 < NP2K.
The principal component (PC) analysis results (Fig. 4) indicated that PC1 explained 32.5% of the
total variance in the 95 carbon source data, mainly due to substrates of amino acids, carboxylic acid, and
amine (Table II). PC2 explained 9.1% of the variance by mainly representing carbohydrate, polymer,
and miscellaneous substrates. The distribution of the different treatments in the PCA pattern was
almost random with considerable variation among their replicates. The tendency of different treatments
between PC1 and PC2 was not identified.