关键词: 哈尼梯田系统, 土壤有机碳, 土壤全氮, 碳氮比, 时空分布

Abstract: 【Objective】 The contents and changes of soil carbon,nitrogen and C/N were studied in Hani terrace of Honghe,and to provide scientific basis for water and fertilizer utilization and management of Hani Terrace in Honghe,Yunnan Province.【Method】 Xiaozhai village,a typical Hani terrace system with "four elements isomorphism" was selected and divided into Hani terrace and forest grassland,0-20 cm soil layer of forest and grassland (divided into arbor forest,shrub forest and grassland) and terrace (divided into upper,middle and lower sampling points along the main irrigation canal) were sampled and measured monthly.【Result】 The organic carbon content in the study area was 35.67-66.40 g/kg,the average value was 50.69 g/kg,the total nitrogen content was 1.97-2.373 g/kg,the average value was 2.31 g/kg.The average organic carbon content of forest and grassland was 66.06 g /kg,the terraced field is 37.72 g/kg; the average total nitrogen content of forest land is 2.37 g/kg,and the terraced field is 2.25 g/kg.The soil organic carbon content in different months is 20.62-82.64 g/kg,and the nitrogen content is 1.65-2.81 g/kg.There is no obvious regularity in the change of soil organic carbon content between months,most of which belong to medium variation and the difference is not significant.Total nitrogen has monthly regularity,with the front value appearing in April to June and the trough value appearing in August to November.The soil organic carbon content and total nitrogen content have moderate to weak variation in space and time,and the significant differences are mainly manifested in space.The C/N of different land uses in Hani terrace system is 15.67-28.14,the average C/N of forest and grassland is 28.06,and the average C/N of terraces is 16.99.The C/N law is opposite to the temporal and spatial distribution of nitrogen.【Conclusion】 The soil organic carbon and total nitrogen content in the study area are relatively high,among which the forest grassland is higher than the terraced fields; the farmland is more conducive to the release and supply of nitrogen than the forest grassland soil.The nitrogen content of the farmland decreases from August to October and C/N increases,nitrogen needs to be supplemented in time.

Key words: Hani terrace system, soil organic carbon, soil total nitrogen, carbon-nitrogen ratio, spatial and temporal distribution