5. Conclusion
Our result showed that N, P and NP addition could significantly affect
the decomposition of litter matter, and P addition could alleviate the
inhibitory effect of litter decomposition by high N concentration. N and
P had an interactive effect on the decomposition of litter matter. The
lignin remaining rate of litter was slightly enriched in the late stage
of decomposition, which was most obvious in high N treatment, while the
cellulose remaining rate decreased continuously with decomposition time.
Litter C, N and P basically showed a continuous release pattern, with
the strongest promoting effect in NP treatment. All additive treatments
significantly increased soil invertase, cellulase, polyphenol oxidase,
urease, and phosphatase activities, which were generally higher in the
NP treatment than the other treatments. The rate of litter decomposition
was significantly influenced by nutrient content as well as soil enzyme
activity, where cellulose content and invertase activity may be a key
factor controlling the rate of litter decomposition.