中文摘要：

设置半封闭开顶式人工气候室,研究大气CO2浓度升高与不同施氮肥处理相互作用对新疆滴灌棉田土壤氮含量变化的影响。在不同CO2浓度（360、540μmol·mol-1和720μmol·mol-1）条件下,不同施N处理（0、150、300 kg·hm-2和450 kg·hm-2）对棉花花铃期0～20 cm和20～40 cm土壤NH＋4-N、NO-3-N和全N含量变化进行测定。结果显示：相对于对照CO2浓度处理,当CO2浓度为540μmol·mol-1时,各施氮水平下土壤NO-3-N含量降低,且高氮处理下降低更为显著,全N含量无显著变化;土壤NH＋4-N含量在N0、N150水平有小幅度增加,在N300、N450水平降低。当CO2浓度为720μmol·mol-1时,土壤NO-3-N、全N含量仍是降低的,但降低幅度低于CO2 540处理;而土壤NH＋4-N含量表现为显著增加。每个CO2浓度处理下,随着施氮肥水平增加,土壤NH＋4-N、全N含量呈增加趋势,但高N处理增加比例低于低N处理;土壤NO-3-N含量变化不大。总体比较,CO2 540-N300处理,土壤NO-3-N含量显著低于其他C、N组合。0～20 cm、20～40 cm两个土层之间,土壤中不同N素变化趋势基本一致,但0～20 cm土层土壤N养分含量变化更为明显。研究表明：大气CO2浓度升高为540μmol·mol-1时,在施N 300 kg·hm-2处理下,更有利于棉花对土壤N尤其是NO-3-N养分的吸收利用。

英文摘要：

This research, conducted in a semi-closed and top-open artificial climate chamber, investigated the impact of nitrogen （N） fertilizer application at varied CO2 levels on the soil nitrogen content in a drip irrigation cot- ton field. Total N, NH4 -N and NO3- -N in soil were monitored and measured when cotton blooming at different N fertilizer application levels under certain CO2 density. The results showed that NO3- -N in the soil decreased with the increase of N fertilizer applied when CO2 density was at 540 μmol· mol - 1 and the more the N fertilizer applied, the faster the decrease of NO3--N in the soil while there was no significant change the rate of decrease was less than under CO2 density was at 540 μmol · mol- 1, of the total N in the soil. Although NO3- -N and the total N in the soil decreased with the increase of the N fertilizer applied when CO2 density was at 720 μmol · mol- 1 while NH4 -N in the soil increased with the increase of the N fertilizer applied. NH4＋ -N in the soil increased with the increase of the N fertilizer applied at all CO2 density levels in general. There was no obvious difference in soil nitrogen between different soil layers. The study suggested that it was appropriate for cotton to absorb and utilize N particularly NO3- -N when CO2 density was at 540 μmol · mol-1 and the N fertilizer applied at 300 kg · hm-2.