长期施肥对水稻土土壤有机碳矿化的影响

以湖南省3个国家级稻田肥力变化长期定位监测点的土壤为材料，通过室内分析和培养试验，研究了不同施肥处理下土壤有机碳矿化特征及土壤总有机碳、微生物量碳和水溶性有机碳对土壤有机碳矿化的影响.结果表明：3个监测点各施肥处理的土壤CO₂累积排放量为448.64～1 516.77 μg·g^-1，CH₄累积排放量为15.60～33.34 μg·g^-1，在58 d的培养期内土壤有机碳矿化量占总有机碳的3.59%～5.57%；不同处理CO₂的产生速率均在前期保持较高水平，之后迅速下降，后期较慢并趋于平稳，CH₄的产生速率表现为先缓慢升高后迅速降低的变化趋势；化肥配施有机肥处理显著增加了CO₂和CH₄的累积排放量；不同施肥处理土壤有机碳矿化量与总有机碳、微生物量碳和水溶性有机碳含量之间的相关性达到了极显著水平，而与矿化量所占土壤总有机碳的比例无明显相关关系.

Effects of long-term fertilization on paddy soil organic carbon mineralization.

An incubation test was conducted with the paddy soil samples collected from three national long-term experiment stations in Hunan Province to study the characteristics of organic carbon mineralization under different fertilization treatments and its relationships with organic carbon fractions, i.e., total organic carbon (TOC), microbial biomass carbon (MBC), and water-soluble organic carbon (WSOC). The results showed that in all fertilization treatments, the cumulative amounts of CO2 and CH4 ranged from 448.64 to 1516.77 microg x g(-1) and from 15.60 to 33.34 microg x g(-1), respectively. In the 58 days of incubation, the mineralized carbon accounted for 3.59%-5.57% of TOC. The CO2 production rate was higher in the early phase of incubation, decreased rapidly then, and tended to stable afterwards; while the CH4 production rate had a slow increase first and declined rapidly then. A combined application of chemical fertilizers and manure or straw increased the cumulative amounts of CO2 and CH4 significantly. In all fertilization treatments, the cumulative mineralized C had significant correlations with TOC, MBC and WSOC, but less correlation with its percentage in TOC.