【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。更多还原

【Abstract】 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 15N-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 soil.更多还原