摘要
利用中国唯一的稻麦轮作FACE(free-air carbon dioxide enrichment,开放式空气CO2浓度增高)试验平台,研究大气CO2浓度升高对稻季土壤中小麦秸秆降解速率及其氮素分趋的影响。试验设置Ambient(目前空气对照)和FACE(Ambient+200μmol.mol-1)两个CO2浓度以及低氮处理(LN,150 kg.hm-2)和高氮处理(HN,250 kg.hm-2)两个氮肥水平,在稻季之初按标记麦秸/土壤重量比0.3%添加15N标记小麦秸秆,根据水稻生长时期依次采样测定秸秆降解速率,并通过分析土壤全氮、植株全氮及其15N丰度来观察已降解秸秆的氮素分趋情况。结果发现,大气CO2浓度升高对高氮处理土壤中小麦秸秆降解速率没有显著影响,但显著促进了低氮处理土壤中小麦秸秆的降解(p<0.05),使其提高到与高氮处理土壤相当水平;大气CO2浓度升高显著增加了已降解秸秆中氮素的流失,在高氮处理土壤中尤为严重,而对植物吸收已降解秸秆中的氮素没有显著影响。结果表明,大气CO2浓度升高在土壤氮素相对不足时会加速土壤中小麦秸秆的降解,而在土壤氮素相对充足时又会加大降解秸秆中氮素的流失。
The effects of elevated atmospheric CO2 concentration on the rate of wheat straw decomposition and nitrogen distribution of decomposed straw in paddy soil was investigated under a FACE （ Free air Carbon dioxide Enrichment） system in Yangzhou, Jiangsu, China. This experiment included two levels of atmospheric CO2 concentration and application rate of N fertilizer with the amendment of 15 N-labelled wheat straw at a 0.3 % ratio of straw to soil. Periodically, soil samples were collected for the analysis of straw decomposition rate, total nitrogen content, as well as ^15N abundance in soil and plant. The elevated atmospheric CO2 concentration had no significant effect on the decomposition rate of wheat straw under high soil N level while significantly increased the decomposition rate under low soil N level. The elevated atmospheric CO2 concentration increased more N loss from decomposed wheat straw, especially under high soil N level, but did not affect plant N uptake of the decomposed wheat straw. Our results suggest that elevated atmospheric CO2 concentration could increase straw decomposition in N-limited soil, while result in significant N loss from the decomposed straw in N-saturated
出处
《生态学报》
CAS
CSCD
北大核心
2009年第5期2535-2540,共6页
Acta Ecologica Sinica
基金
国家自然科学基金资助项目(40571156)
中国科学院知识创新工程重要方向资助项目(KZCX-SW-440)
关键词
大气CO2浓度升高
秸秆降解
氮素分趋
氮肥水平
free air carbon-dioxide enrichment
straw decomposition
nitrogen distribution
nitrogen application level
