好气与淹水条件下水稻土各粒级团聚体有机碳矿化量

Organic carbon mineralization in various size aggregates of paddy soil under aerobic and submerged conditions

采用室内恒温培养法观测了好气和淹水处理下水稻土不同粒级团聚体中有机碳矿化的动态变化.结果表明:两种处理下,各粒级团聚体中有机碳矿化量都表现为培养前期快速下降,培养后期保持相对稳定的趋势.不同粒级团聚体之间有机碳矿化速率存在明显差异,在整个培养过程中,均以1～2mm粒级团聚体最高,以<0.053mm粒级团聚体最低.统计分析表明,不同粒级团聚体中有机碳矿化量变化与有机碳和微生物生物量碳含量呈显著线性相关.好气和淹水处理下对土壤总有机碳累计矿化量贡献最大的是0.25～1mm粒级团聚体,分别达41.77%和34.11%;好气处理下贡献最小的是<0.053mm粒级团聚体,淹水处理下贡献最小的是1～2mm粒级团聚体,分别仅为7.8%和6.6%.

With incubation tests in laboratory, the mineralization of organic carbon in various size aggregates of paddy soil was investigated under aerobic and submerged conditions. The results showed that the organic carbon mineralization in various size aggregates decreased quickly at the beginning of the incubation, but remained stable during the late period of incubation. The mineraliza- tion rate varied significantly with the size of the aggregates. Through the incubation time, the organ- ic carbon in 1-2 mm aggregates had the highest mineralization rate, while that in 〈 0. 053 mm ag- gregates had the lowest one. Statistic analyses indicated that the mineralization rate of organic car- bon in various size aggregates was significantly and linearly correlated with the contents of organic carbon and microbial biomass carbon in the aggregates. 0. 25-1 mm aggregates had the highest con- tribution to the cumulative mineralization of soil organic carbon, accounting for 41.77% under aero- bic condition and 34. 11% under submerged condition, while 〈 0. 053 mm and 1-2 mm aggregates had the lowest contribution under aerobic and submerged conditions, accounting for 7.8% and 6.6% , respectively.