• 关键词：δ¹³C  玉米  土壤有机碳  根际碳沉积  碳汇

• 基金项目：中国科学院知识创新工程重大项目(No.KZCX1-SW-01-05);国家杰出青年基金项目(No.40125004)

• 杨兰芳
• 1. 土壤与农业可持续发展国家重点实验室, 中国科学院南京土壤研究所, 南京 210008; 2. 湖北大学资源环境学院, 武汉 430062; 3. 中国地质大学环境学院, 武汉 430074

• 蔡祖聪
• 土壤与农业可持续发展国家重点实验室, 中国科学院南京土壤研究所, 南京 210008

• 摘要：设置了两种土壤施氮水平(150和300 mg·kg^-1),3个生长时期(喇叭期、开花期和成熟期)收获玉米植株的土壤盆栽试验,采用同位素质谱法测定玉米植株和土壤有机碳的δ¹³C值,以研究玉米植株生长和施氮水平对土壤有机碳更新的影响.结果表明,玉米植株的δ¹³C值为-12.9‰～-13.2‰,受玉米生长时期和施氮水平的影响不显著;种植玉米后,土壤有机碳含量增加,说明在供试土壤上,玉米生长促进了土壤碳汇的作用;玉米生长和施氮水平显著影响土壤有机碳的δ¹³C值和土壤有机碳的更新.根据土壤有机碳δ¹³C变化计算,玉米根际碳沉积对土壤有机碳的贡献为4%～25%,随玉米生长时间的延长,玉米根际碳沉积对土壤有机碳的贡献增大.种植一季玉米后,低氮处理的土壤有机碳的δ¹³C值大于施用高氮的处理,但土壤总有机质含量低于高氮处理.由此说明,在养分不足的条件下,玉米根分泌物可能更能激发土壤原有机质的矿化,从土壤中获得更多的养分.

• Abstract：In order to understand the effect of growing maize and N application on the renewal of soil organic carbon (SOC), a pot experiment with two N application rates (150 and 300 mg·kg^-1) and harvesting maize at three growing stages (trumpeting, flowering, and ripening stage, respectively) was conducted and the values of δ¹³C in maize plant and SOC was determined by mass spectrometer. The results showed that the values of δ¹³C in maize plant were -12.9‰～-13.2‰, which were not affected by growing stages and N application rates. The SOC content was increased after maize planting, but decreased in the bare soil, indicating that growing maize enhanced the function of soil as a carbon pool. And growing maize and N application rates influenced obviously the value of δ¹³C and renewal of SOC. Based on the changes in δ¹³C, the contribution of rhizodeposition to SOC was calculated to be from 4% to 25%, increased with the maize growing time. After the maize harvesting, the contribution of rhizodeposition to SOC was larger in low N application rate than in high N application rate, but the total content of SOC was higher in high N application rate than in low N application rate. The results indicated that the mineralization of the original SOC was accelerated by maize root exudations more significantly in low N application rate than in high N application rate, which was probably due to more N demands from soil organic matter in the case of low N application rate.

• Key words：δ¹³C  maize  soil organic carbon  rhizodeposition  carbon pool

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