鄱阳湖区不同围垦年限稻田土壤碳氮变化

Soil organic carbon and total nitrogen in reclaimed paddy fields vary with reclamation duration in Poyang Lake region

在鄱阳湖围垦典型区测定了6个不同围垦年限稻田的土壤有机碳（SOC）、全氮（TN）含量,以阐明鄱阳湖区湿地开垦为稻田后有机碳、全氮的变化规律。结果表明：土壤0~10、10~30、30~50 cm有机碳含量变化范围分别为13.7~28.5、7.1~15.3和5.1~10.4g·kg^-1,相应土层全氮含量变化范围分别为1.2~3.6、0.9~2.0、0.7~1.3 g·kg^-1,有机碳与全氮之间呈极显著正相关（P〈0.01）。土壤层次与围垦年限以及二者之间的交互作用均显著影响有机碳及全氮含量,表现为表层土壤有机碳与全氮含量均显著高于底层,且表层有机碳与全氮含量随围垦年限呈显著增加趋势,土壤碳氮比（C/N）相对稳定。

Wetland conversion to reaches of Yangtze River. As the cropland was a typical land use change in the middle and lower largest freshwater lake of China, there were 1466.9 km^2 re- claimed croplands in Poyang Lake region. To clarify the dynamics of soil organic carbon （ SOC ） and total nitrogen （TN） contents in the reclaimed croplands in Poyang Lake region, we collected soil samples from paddy fields that were reclaimed during six different periods in typical reclama- tion area. Subsequently, SOC and TN were measured. Our results showed that SOC content ranged from 13.7 to 28.5 g ·kg^-1 for 0-10 cm soil layer, 7.1 to 15.3 g ·kg^-1 for 10-30 cm soil layer, and 5.1 to 10.4 g·kg^-1 for 30-50 cm soil layer, respectively. TN contents in the corre- sponding soil layers varied from 1.2 to 3.6, 0.9 to 2.0 and 0.7 to 1.3 g ·kg^-1 , respectively. SOC contents were significantly positively correlated with TN contents （P〈 0.01 ）. Soil layers, recla- mation periods and their interactions had significant impacts on SOC and TN contents. SOC and TN contents decreased with soil depth. Moreover, SOC and TN contents in top soils showed a sig- nificantly increasing trend with increasing reclamation duration. The soil C/N ratios were main- tained relatively stable.