易利用态有机物质对水稻土甲烷排放的激发作用

为探讨外源有机物质对淹水稻田土壤CH4排放的激发作用,对比不同外源有机物质对土壤CH4排放的贡献差别,本研究选取3种标记的易利用态有机物(葡萄糖、乙酸和草酸)分别加入水稻土,进行了为期1个月的培养。结果表明:培养30 d后不同处理CH4的累计排放量差异显著(P0.05),其中,乙酸葡萄糖草酸对照;双因素方差分析结果显示,外源有机物质的添加加速了土壤易利用态有机质的矿化(即产生正激发效应);不同处理条件下激发作用产生的CH4分别占各处理CH4总累计排放量的73.3%(葡萄糖处理)、71.5%(乙酸处理)和40.9%(草酸处理),且CH4排放量与CH4激发效应之间极显著正相关关系说明土壤CH4排放主要要来自于土壤原有机质的分解,外源有机物质可能主要对土壤微生物活性及代谢途径有影响。

Priming Effects of Labile Organic Substances on Methane Emission in Flooded Paddy Soil

In order to clarify the priming effect and contribution of exogenous organic matter on CH₄ emissions, an incubation experiment was carried out with three ¹³C-labeled organic substances (glucose, acetic acid, and oxalic acid) in a paddy soil for one month. The results showed that cumulative CH₄ emissions were significantly different among different treatments, in an order of acetic acid > glucose > oxalic acid > control (P<0.05). Two-way ANOVA indicated that the decomposition of soil native organic matter was accelerated with the addition of exogenous organic matter (positive priming effect). The percentages of priming effect (PE) CH₄ from soil were about 73.3% (glucose), 71.5% (acetic acid) and 40.9% (oxalic acid) of total CH₄, respectively. Different PEs and the significantly positive correlations between CH₄production and PE demonstrated that exogenous organic matter can promote soil CH₄ emission, mainly because of their PE on original soil organic matter. The major role of exogenous organic matter on soil native organic matter decomposition may be due to their effects on soil microbial activity metabolism.