Abstract: Based on a 25-year long-term fertilization experiment, the effects of different fertilizing treatments on labile organic carbon and carbon pool management index in cinnamon soil were analyzed. The results showed that compared with no fertilizer application (CK), the treatments of different fertilizer applications increased the contents of WSOC and LFOC in cinnamon soil. The contents of WSOC in the treatments of manure combined with chemical nitrogen and phosphorus fertilizer applications (M₁NP, M₂NP) were 93% and 99% higher than that of CK, respectively. The effect of higherrate manure applications with chemical fertilizer (M₂N, M₂NP) on LFOC were more significant, increasing the content of LFOC by 240% and 360% compared to CK, respectively. After longterm application of single chemical and manure fertilizer, the content of EOC kept no significant change, while it increased significantly under the treatment of applying manure combined with chemical fertilizer. The distribution proportion of WSOC increased under the application of single manure fertilizer but decreased in the other treatments. Compared with CK, the proportion of LFOC in SOC decreased significantly under the single nitrogen fertilization but increased significantly under higherrate manure application chemical fertilizer. The distribution proportion of EOC decreased under single chemical fertilizer application. Single chemical fertilizer application had a lower soil organic carbon pool management index (CPMI) compared with CK. Longterm application of manure alone or combined with chemical fertilizer were effective measures to promote CPMI. In these treatments, M₂N and M₂NP had the most significant effect, and the CPMI increased by 145% and 180% compared with CK, respectively. The correlation analysis indicated that under the longterm fertilization application, the contents of WSOC, LFOC and EOC were significantly positively correlated to each other, and had a strong positive correlation with the total organic carbon content.

Key words: crop growth, ammonia volatilization, straw-derived biochar, biochar-C loss, successive incorporation