氮输入对小叶章不同生长阶段土壤CH_4氧化的影响

用盆栽法对小叶章不同生长阶段土壤CH_4氧化能力随时间变化进行了研究.结果表明,氮输入后,植物各生长阶段的CH_4氧化率均随时间推移发生了明显的波动变化.从生长季(6月7日～8月24日)CH_4氧化率均值来看,只有12g/m~2处理对CH_4氧化起促进作用,且12g/m~2和24g/m~2处理之间存在显著性差异(n=4,P0.05).不同氮输入水平对植物不同生长阶段CH_4氧化率影响明显.第一阶段(6月7日～7月2日)适量(6g/m~2)氮输入对CH_4氧化起促进作用,但过量(12g/m~2)氮输入则起抑制作用.第二阶段(7月2日～7月20日)只有12g/m~2处理起促进作用.第三(7月20日～8月7日)、四(8月7日～8月24日)阶段氮输入对CH_4氧化起抑制作用.氮输入后,土壤微生物量碳(MBC)、土壤微生物量氮(MBN)、土壤基础呼吸(BR)、土壤代谢熵(qCO_2)、土壤诱导呼吸(SIR)、铵态氮(NH_4~+-N)、硝态氮(NO_3~--N)和植物地上生物量与土壤CH_4氧化的动态关系存在差异.土壤CH_4氧化仅与MBC呈极显著负相关(P0.01),与其他影响因子相关性较小.

Effects of exogenous nitrogen on methane oxidation at different plant growth phase from Deyeuxia angustifolia marsh

The abilities of CH4 oxidation changing with time were studied by using pot-culture method at different growth stages of D.angustifolia. The time variation of CH4 oxidation rate showed smart volatility after nitrogen input at each growth phase. From the perspective of the mean CH4 oxidation rate of growing season (June 7~August 24), only the medial nitrogen level promoted CH4 oxidation, and there existed significant differences between medial and high nitrogen level (n = 4, P < 0.05). The effect of different nitrogen input level on the CH4 oxidation rate was obvious at different growth stages. The first stage, moderate nitrogen input promoted CH4 oxidation, but excessive nitrogen input suppressed CH4 oxidation. The second phase, only medial nitrogen level promoted CH4 oxidation. The third and fourth stages, nitrogen input both suppressed CH4 oxidation. After nitrogen inputted, there were differences in dynamic relationships between soil microbial biomass C and N (MBC, MBN), soil basic respiration (BR), soil metabolic quotient (qCO2), soil induced respiration (SIR), ammonium nitrogen (NH4+-N), nitrate nitrogen (NO3--N), plant biomass and CH4 oxidation. Through correlative analysis, CH4 oxidation was significantly related to MBC (P < 0.01).