增温条件下不同土壤粒级有机碳和全氮的分布

目的]分析气温上升后土壤养分的变化情况,为今后应对全球变暖提供数据支持。方法]以中国华北平原的耕地褐土为材料,采用沉降虹吸法,研究在增温条件下土壤3个粒级有机无机复合体组成以及有机碳和全氮的变化情况。结果]土壤有机无机复合体分布在增温条件下没有明显变化。有机碳含量增加而全氮含量降低。从不同粒级来看,3种粒级的有机碳含量都有增加,而全氮含量在个别小粒级会有所增加而砂粒的全氮含量变化不明显。土壤碳氮比比较稳定。有机碳分配有往大粒级转移的趋势,而全氮分布未表现出明显规律。结论]增温在一定程度上加速有机质分解使得土壤有机碳含量上升,在较小粒级上更加明显。而全氮含量因为反矿化等作用会出现下降,但是相比对照组有增长。

Distribution of Organic Carbon and Total Nitrogen in Different Soil Grain Under Temperature Increase

Objective] To analyze the changes of soil nutrients after temperature increase, in order to provide data support for responses to global warming in the future.Methods] The brown soil of cultivated land in North China plain was taken as study material. Sedimentation Siphon method was used to study the composition of three granular organic-inorganic complexes and the variation of organic carbon and total nitrogen in soil under increasing temperature.Results] The distribution of soil organic and inorganic complexes showed no significantly change under the condition of increasing temperature. Organic carbon content increased while total nitrogen content decreased. In terms of different grain levels, the content of organic carbon in all three grain grades increased, while the content of total nitrogen only increased in some small soil grain. No significant change was fond in the content of total nitrogen in sand grains. The soil carbon nitrogen ratio was relatively stable. The distribution of organic carbon tended to shift to large grain size, while the distribution of total nitrogen showed no obvious pattern.Conclusion] Temperature increase accelerated the decomposition of organic matter, and increased the content of soil organic carbon, especially in smaller grain size. In contrast, the total nitrogen content decreased as a result of anti-mineralization, but it showed a relative increase trendcompared with the control group.