大气CO_2浓度升高和施氮对棉田土壤理化性质及微生物区系的影响

Influence of elevated CO_2 and nitrogen supply on cotton field soil properties and microbial flora

为明确大气CO2浓度升高和不同施氮水平对新疆棉田土壤理化性质和土壤微生物区系状况的影响，基于滴灌棉田管网系统，对背景CO2浓度（360μmol．mol-1）和高CO2浓度（540μmol．mol-1和720gmol·mol-1）条件下不同施氮处理（0kgN／hm2、150kgN／hm2、300kgN／hm2和450kgN／hm2）的0～20cm和20-40cm土壤有机碳、全氮、碳酸氢根和pH值以及土壤中细菌、真菌、放线菌等指标的影响进行了评价。结果表明：在各施氮水平上，当CO2浓度升高到720lμmol．mol-1时，0—40cm土壤有机碳、全氮含量趋于减少，土壤pH值趋于降低，土壤碳酸氢根及总盐含量无明显变化；在各施氮水平上，当CO2浓度升高到540gmol·mol-1和720μmol．mol-1时，0-40cm土壤中细菌和0～20cm土壤中放线菌数量均呈增加趋势，20～40cm土壤中真菌的数量则呈减少趋势。研究表明，棉田土壤理化性质和微生物区系对大气CO2浓度升高和施氮水平有一定的响应。

To illuminate influence of elevated CO2 and nitrogen supply on cotton field properties and microbial flora in the plot experiment, this study investigated organic carbon, total nitrogen, bicarbonate ion, pH, total salt and soil bacteria, soil fungi, soil actinomycetes under ambient CO2 （360 μmol.mol-1） and elevated CO2 （540 and 720 μmol＇mol-t） at 4 nitrogen levels （0, 150, 300 and 400 kgN/hm2）. The results showed that, organic carbon, total nitrogen and pH at a soil depth of 0-40 cm tended to decrease elevated CO2 （720 μmol.mol-1） at different nitrogen levels, but less effects on soil bicarbonate ion and total salt were found. Both bacteria population at a soil depth of 0-40 cm and actinomycetes population at 0-20 cm were enlarged, but fungi population at 20-40 cm soil depth tended to decrease under elevated CO2 concentration （540 and 720 μmol.mol-1 at different nitrogen levels.