Abstract: We took restoration lands using alfalfa pastures as research objects and determined contents of total organic carbon (C),total nitrogen (N),and total phosphorous (P) in soil,as well as stoichiometric ratios across different ecological restoration years.Five sampling lands were selected,which were restored naturally for 3 years (CK1),restored using alfalfa pasture for 3 years,8 years,20 years,and local cropland (CK2),respectively. Results showed that:The contents of C and N increased and the content of P was not changed considerably in the restoring process. The contents of C and N decreased with the increase of soil depth in alfalfa pasture for 20 years and CK2. The contents of C and N in alfalfa pasture for 20 years in 0~10cm were 30.1% and 28.8% higher than CK2,respectively. And in 0~40cm they were similar to CK2.The ratios of C:P and N:P tended to increase with the increase of restored years,the ratios of C:N tended to increase at the beginning and then decrease;The ratios of C:P,N:P and C:N in alfalfa pasture for 20 years were close to that in CK2. C content and N content,C:P,N:P and C content,N content were in positive correlation,but C:N had no significant correlation with C content and N content.Long-term alfalfa restoration is of great significance for restoration of soil C content and N content. Soil C:P and N:P were mainly restricted by soil C and N content in soil restoration process,respectively. It suggests that C and N is more sensitive to vegetation recovery at this restoration soil.

Key words: Soil nutrients, stoichiometry, vertical variation, ecological restoration, Alfalfa

摘要： 对山西安太堡露天矿排土场不同复垦年限苜蓿地（3年、8年、20年），自然恢复地和耕地不同深度土壤总有机碳（C）、全氮（N）、全磷（P）及其化学计量比进行分析，结果表明：土壤C、N随复垦年限延长递增，P相对稳定；耕地和20年苜蓿地，C、N随土层深度增加递减。20年苜蓿地0～10 cm土壤C、N分别较耕地提高30.1%和28.8%；0～40 cm与耕地接近，说明复垦能提高，特别是提高表层土壤C、N质量分数。C∶P，N∶P随复垦年限增加而上升，C∶N呈先增加、后降低的趋势；20年苜蓿地0～40 cm土壤C∶N，C∶P，N∶P均与耕地接近。土壤C和N极显著相关，C∶P，N∶P与C、N极显著相关，C∶N与C、N相关性不显著，说明C∶P，N∶P分别由碳、氮控制，C∶N受碳、氮共同控制，生物措施对复垦土壤C、N的提升作用比P明显。

关键词: 土壤养分, 化学计量特征, 复垦年限, 垂直变异, 苜蓿