大气CO_2浓度升高对稻田土壤Ca、Mg含量的影响

为了研究稻田生态系统中土壤钙、镁元素生物地球化学循环对大气CO2浓度升高的响应。利用中国稻/麦轮作FACE（Free Air Carbon-dioxide Enrichment）试验平台,研究大气CO2浓度升高（比周围大气高200μmol mol-1）对2007年稻季各生育期不同深度土壤溶液ρ（Ca）、ρ（Mg）的影响。结果表明,大气CO2浓度升高降低了5 cm处土壤溶液ρ（Ca）、ρ（Mg）,有增加稻季30、60和90 cm处土壤溶液ρ（Ca）的趋势,其增幅分别为18.3%、12.4%和15.3%;大气CO2浓度升高会增加稻季Ca淋溶损失风险;稻季不同深度土壤溶液ρ（Ca）、ρ（Mg）对大气CO2浓度升高的响应有所不同。稻田生态系统不同深度土壤Ca、Mg循环对大气CO2浓度升高的响应值得深入研究。

Effect of CO2 enrichment on Ca and Mg concentration in soil solution in the rice season

To understand the response of soil Ca and Mg geochemical recycle in rice paddy ecosystem to elevated atmospheric CO2,field experiment was carried out at Experiment Station of FACE（free-air carbon dioxide enrichment） in China.There were two treatments,including ambient（the CO2 concentration was approximately 370 μmol·mol？1） and FACE（the target CO2 concentration was 200 μmol·mol？1 higher than that of ambient）.Concentrations of Ca and Mg in soil solution at different depth in the rice season in 2007 were determined.The results showed that elevated CO2 decreased ρ（Ca） andρ（Mg） in soil solution at 5cm depth,and increased Ca concentration in soil solution at 30,60 and 90cm depth in the whole rice growth period,with 18.3%,12.4% and 15.3%,respectively.This indicates that elevated atmospheric CO2 can increase the Ca loss via leaching from soil.The responses of Ca and Mg in soil solution at different layers to elevated atmospheric CO2 were different.