摘要
为明确不同土地利用方式土壤中无机氮转化的过程速率,深入理解土地利用方式改变对土壤氮循环和生态环境的影响,以云贵高原草海自然保护区的湿地、旱地、菜地和林地土壤为对象,通过室内培养试验,采用^(15)N同位素成对标记技术和FLUAZ数值优化模型研究不同利用方式土壤氮初级转化速率的差异。结果表明,土地利用方式对土壤氮初级转化速率具有显著影响。湿地土壤的氮初级矿化速率(11.95 mg·kg^(−1)·d^(−1),以N计,下同)和固定速率(6.13 mg·kg^(−1)·d^(−1))最高,林地土壤的氮初级矿化速率最低(2.39 mg·kg^(−1)·d^(−1)),但是氮初级固定速率(2.09 mg·kg^(−1)·d^(−1))与旱地土壤(2.29 mg·kg^(−1)·d^(−1))和菜地土壤(1.52 mg·kg^(−1)·d^(−1))没有显著差异。林地土壤的初级硝化速率(0.77 mg·kg^(−1)·d^(−1))显著低于湿地土壤(2.68 mg·kg^(−1)·d^(−1))、旱地土壤(6.33 mg·kg^(−1)·d^(−1))和菜地土壤(5.39 mg·kg^(−1)·d^(−1))。旱地土壤和菜地土壤的初级硝化速率与铵态氮固定速率之比以及氮初级矿化速率与初级固定速率之比均大于1,而湿地土壤和林地土壤的初级硝化速率与铵态氮固定速率之比均小于1,且林地土壤的氮初级矿化速率与初级固定速率之比接近1。结果表明,林地土壤相对于其他三种土壤而言,土壤中氮素矿化和固定过程耦合更为紧密,从而减少了硝化作用的发生及硝态氮的淋溶风险。本研究结果可为草海自然保护区土地利用方式的合理布局及生态修复工程的环境效应评价提供科学依据。
【Objective】To understand the effects of land use type change on soil N cycle and eco-environment,this study aimed to elucidate the gross N transformation rates in soils under different land use types.【Method】A laboratory incubation experiment was conducted using a ^(15)N labeled technique and the numerical FLUAZ model to study the difference of gross Ntransformation rates among soils under different land use types such as wetland, dryland, vegetable land, and forest land in theCaohai nature reserve located in the Yunnan-Guizhou Plateau. 【Result】 The results showed that land use type significantlyaffected gross N transformation rates in the soils. Wetland soil had the highest rates of gross N mineralization (11.95 mg·kg^(−1)·d^(−1))and immobilization (6.13 mg·kg^(−1)·d^(−1)) while the forest soil had the lowest gross N mineralization rate (2.39 mg·kg^(−1)·d^(−1)), but thegross N immobilization rate (2.09 mg·kg^(−1)·d^(−1)) was comparable to that of dryland soil and vegetable soil (2.29 and 1.52mg·kg^(−1)·d^(−1), respectively). The gross nitrification rate of forest soil (0.77 mg·kg^(−1)·d^(−1)) was significantly lower than that ofwetland soil, dryland soil, and vegetable soil(2.68, 6.33 and 5.39 mg·kg^(−1)·d^(−1), respectively). The ratios of gross nitrification toNH4+ immobilization and gross N mineralization to the immobilization of dryland soil and vegetable soil were both >1, whereasthe ratio of gross nitrification to NH4+ immobilization rate was <1 in wetland soil and forest soil, and the ratio of gross Nmineralization to the immobilization rate was close to 1 in forest soil. The gross N mineralization rate was significantly positivelycorrelated with soil organic carbon (SOC), total nitrogen (TN), C/N ratio, and soil pH, and significantly negatively correlated withsilt content. Also, the gross N immobilization rate and ammonium immobilization rate were significantly positively correlatedwith SOC, TN, water-soluble organic C(SOCw), and soil pH, and significantly negatively correlated with silt content. The grossnitrification rate was significantly negatively correlated with SOCw and clay content and significantly positively correlated withsand content. 【Conclusion】 The results indicate that in comparison with the wetland soil, dryland soil, and vegetable soil, themineralization and immobilization processes in forest soil were more tightly coupled, thereby decreasing the occurrence ofnitrification and subsequent NO3- loss to the environment. The results of this study can provide a scientific basis for the rationallayout of land use and the evaluation of the environmental effects of ecological restoration projects within the Caohai NatureReserve.
作者
郎漫
聂浩
朱四喜
李平
LANG Man;NIE Hao;ZHU Sixi;LI Ping(School of Ecology and Applied Meteorology,Nanjing University of Information Science&Technology,Nanjing 210044,China;School of Eco-Environmental Engineering,Guizhou Minzu University,Guiyang 550025,China)
出处
《土壤学报》
北大核心
2025年第3期705-715,共11页
Acta Pedologica Sinica
基金
中央土壤污染防治资金项目(新集采单[2021]1468)
国家自然科学基金项目(41301345)资助。
关键词
土地利用方式
氮初级转化速率
矿化
固定
硝化
Land use type
Gross N transformation rates
Mineralization
Immobilization
Nitrification
