不同氮水平下秸秆和活性碳对土壤不同粒级碳的影响

利用采集自FACE(Free Air Carbon Dioxide Enrichment)技术平台上田间培养的土壤样品，通过温室培养的方法，研究不同CO₂浓度下导致作物生物量增加和更多碳输入对土壤含碳量的影响. 结果表明， CO₂浓度高(即通过秸秆还田和根系进入土壤的含碳量增加)时，其显著影响碳在不同粒级土壤中的转化，粒径>53 μm土壤的含碳量增加，粒径<53 μm土壤的含碳量降低；在没有秸秆加入的常规氮水平下与有秸秆加入的低氮水平下，含碳量变化幅度较大；单位土壤各粒级的含碳量均有增加，有秸秆加入，活性碳(葡萄糖)量越大，含碳量增加幅度越大；没有秸秆加入，活性碳量越大，总碳含量增加幅度越小. 而不同氮水平下秸秆的分解代谢对土壤不同粒级碳的影响还不明确，有待继续研究. 

Effects of Straw and Active Carbon on Soil Carbon in Different Sized Particle under Different N Levels

To study the change of soil carbon affected by increase of crops biomass and more carbon input in soil due to elevated CO₂ concentration, a culture experiment on soil from field under Free Air Carbon Dioxide Enrichment (FACE) platform with two CO₂ levels (Ambient CO₂ and Elevated CO₂) and two N levels (NormalN and Low N) was conducted in greenhouse at the same N treatments with field. Results indicated that compared to soil from ambient CO₂ concentration, turnover of different soil particle in soil from Elevated CO₂ concentration was increasedsignificantly and resulted in an increase of soil carbon amount in >53 μm and decrease in <53 μm. The change was larger at Normal N with no straw and at Low Nwith straw added. Carbon amount in bulk soil was increased and it increased morein treatment with increasing of active carbon into soil from root with straw; it was reverse with no straw treatment. However, the effects of decomposition of straw on carbon in different particle-size were dependent on it at different N levels and this was known poor and need more work to carry out.