晋南典型丘陵沟壑区不同土地利用类型对土壤碳氮含量影响研究

Study on the Effect of Different Land Use Types on Soil Carbon and Nitrogen Content in Typical Hilly and Gully Region of Southern Shanxi Province

探讨了晋南典型丘陵沟壑区4种土地利用类型(刺槐(Robinia pseudoacacia)林地、侧柏(Platy⁃cladus orientalis)林地、退耕荒草地、农田玉米地)不同土层深度的碳氮含量变化,为该地区生态恢复与重建提供科学依据.以晋南典型丘陵沟壑区退耕年限、坡度、坡向等相近的4种不同土地利用类型为研究对象,采用稀释热--重铬酸钾容量法和半微量凯氏定氮法测定其不同土层深度的碳氮含量,结果发现,随着土层深度的增加,土壤有机碳和总氮含量逐渐降低;在0 cm~45 cm的土层深度范围内,土壤有机碳含量最高的是侧柏林地,总氮含量最高的为刺槐林地;各土地利用类型土壤有机碳和总氮含量在45 cm~90 cm和90 cm~150 cm土层间无显著差异.林草地的有机碳、总氮含量最高,农田最低.由此可见,土地利用方式从农田到林草地的转变提高了有机碳和总氮的储量.

To explore the changes in carbon and nitrogen content of 4 land use types(Robinia pseudoacacia woodland,Platycladus orientalis woodland,abandoned grassland,farmland corn land)in the typical hilly and gully regions of the Loess Plateau in southern Shanxi Province,And provide a scientific basis for ecological resto⁃ration and reconstruction in this region.Four different land use types with similar length,slope,and aspect,etc.of the typical hilly and gully area in southern Shanxi were studied,and the dilution heat⁃potassium dichromate volumetric method and semi⁃micro Kjeldahl method were used to determine the carbon and nitrogen content of soil at different depths,With the increase of soil depth,the content of soil organic carbon and total nitrogen showed a decreasing trend;at the range of 0 cm~45 cm soil depth,the largest content of soil organic carbon was Platycladus orientalis forest land,and the largest content of total nitrogen was Robinia pseudoacacia forest land;of various land use types there were no significant difference between 45 cm~90 cm and 90 cm~150 cm soil layers on the soil organic carbon and total nitrogen content among different land use types.Conclusion:Forest and grassland organic carbon and total nitrogen content were the largest in forest and grassland,and they were the lowest in farmland.It can be concluded that the content of organic carbon and total nitrogen increased with the transformation from farmland to forest.