不同施肥措施下亚热带稻田土壤碳、氮演变特征及其耦合关系

在湖南省稻田生态系统长期定位监测点研究了不同施肥措施下稻田土壤碳、氮演变及其耦合特征.结果表明：1986—2003年，无肥处理（对照，CK）稻田土壤有机碳和全氮含量略呈下降趋势；化肥（NPK）处理有机碳和全氮含量基本保持稳定，而有机 无机肥配施处理有机碳和全氮含量均呈增加趋势.与对照相比，化肥处理的土壤有机碳和全氮含量分别提高13%和18%，低量有机肥（LOM）处理分别提高54%和45%，高量有机肥（HOM）处理分别提高89%和67%.统计分析表明，土壤有机碳和全氮含量呈显著正相关（P<0.01）.稻田土壤C/N为8.5～12.9，多数分布在10左右.研究表明，有机-无机肥配合施用能在一定程度上促进稻田土壤碳、氮的固定与积累；稻田土壤碳、氮具有较好的耦合关系.

Evolvement characteristics and coupling relationship of soil organic carbon and total nitrogen in subtropical paddy field ecosystem under different fertilization practices.

Soil samples were collected from long-term monitoring plots of paddy field ecosystem in Hunan Province to study the evolvement characteristics and coupling relationship of soil organic carbon and total nitrogen under different fertilization practices. The results showed that in 1986-2003, the contents of soil organic carbon and total nitrogen had a slight decrease under no fertilization (CK), basically remained stable under chemical fertilization (NPK), and increased under the combined application of organic manure and chemical fertilizers. Compared with those in CK, the contents of soil organic carbon and total nitrogen in treatments NPK, low application rate organic manure, and high application rate organic manure were increased by 13% and 18%, 54% and 45%, and 89% and 67% respectively. There was a significant positive correlation (P < 0.01) between soil organic carbon and total nitrogen. The soil C/N was around 10, with the majority ranged from 8.5 to 12.9. It was suggested that a combined application of organic manure and chemical fertilizers on paddy field could increase the sequestration and accumulation of soil carbon and nitrogen to a certain extent, and there existed a better coupling relationship between soil organic carbon and total nitrogen in paddy field ecosystem.