中文摘要：

通过气体原位采集系统对稻麦轮作体系下土壤剖面不同层次N2O浓度动态变化进行了两年田间原位监测。共设4个处理：对照（N0S0）、施氮无秸秆（N1S0）、配施低量秸秆（N1S1）以及配施高量秸秆（N1S2）。结果表明,土壤剖面N2O浓度具有明显的时空分布特征：各处理在小麦和水稻生长前期均出现明显的浓度峰值,施加氮肥加大峰值,添加高量秸秆降低峰值。水稻生长季N2O主要产生在近表层土壤（7 cm和15 cm）,N2O浓度两年均为15 cm≥7 cm≥30 cm≥50 cm;小麦生长季N2O主要产生在下层土壤（30 cm和50 cm）。与N0S0相比,施加氮肥3个处理均显著增加土壤剖面各层次的N2O浓度（p〈0.05）,其中N1S0处理各土层N2O浓度是N0S0处理对应土层的2倍~3倍。配施高量秸秆（N1S2）能显著减少近表层土壤N2O浓度。

英文摘要：

Innovative management practices are required to increase soil fertility and to reduce nitrous oxide （N2O） emission from agricultural soils. Spatial heterogeneity of N2O flux is attributed to various soil properties associated with dif- ferent management practices. N2O flux is the result of integration of N2O production, consumption, and transport proces- ses within soil profiles. N2O production, consumption, and transport processes varied markedly with depth near the soil surface. Variations of N2O concentration were monitored at 7 cm, 15 cm, 30 cm, and 50 cm in depth along a soil profile （ each monitoring point covering a range of 5 cm of soil layer） using an in-situ gas collection system under the rice-wheat annual rotation cropping system. The experiment was designed to have 2 levels of N application and 3 levels of straw incor- poration, i.e. NO IN0 kghm^-2crop^-1） and NI （N250 kghm^-2crop^-1）, and SO （straw0 thm^-2crop^-2）, Sl（straw 3 t hm^-2 rice crop^-1） , and S2 （straw 6 t hm^-2 rice crop^-2） , forming four treatments, i.e. NOS0, N1S0, NIS1 and NI S2, and each treatment had 3 replicates. The observations, once a week over the two cycles of rice and wheat rotations from June 2010 to May, 2012 found that N2O concentrations in soil profiles demonstrated a significant feature of spatiotemporal distribution for all the treatments. N2O concentration peaked during the early growth stages of both wheat and rice, and then fluctuated slightly during the rest of the growth season ; N fertilization significantly boosted the peak, while incorporation of rice straw, particularly in Treatment NI S2, lowered the peak. However, neither N fertilization nor straw incorporation affected seasonal dynamics of N2O concentrations in various soil layers of a profile. During the wheat seasons, distinct N2O concentration distributions were observed in the soil layers at 30 cm and 50 cm in depth. During the first wheat season, N20 concentration in soil profile displayed a decreasing order of 30 cm t〉 50 c