Discrepant responses of soil organic carbon dynamics to nitrogen addition in different layers: a case study in an agroecosystem  

作　　者：Hualing HU Liang ZHAO Wenbing TAN Guoan WANG Beidou XI 

机构地区：[1]Technical Centre for Soil,Agriculture and Rural Ecology and Environment,Ministry of Ecology and Environment,Beijing 100012,China [2]State Key Laboratory of Environmental Criteria and Risk Assessment,Chinese Research Academy of Environmental Sciences,Beijing 100012,China [3]College of Resources and Environmental Sciences,China Agricultural University,Beijing 100193,China

出　　处：《Frontiers of Agricultural Science and Engineering》2024年第2期314-325,共12页农业科学与工程前沿（英文版）

基　　金：financially supported by the National Key Research and Development Program of China (2017YFA0605003)。

摘　　要：Empirical research indicates that heightened soil nitrogen availability can potentially diminish microbial decomposition of soil organic carbon(SOC).Nevertheless, the relationship between SOC turnover response to N addition and soil depth remains unclear. In this study, soils under varying N fertilizer application rates were sampled up to 100 cm deep to examine the contribution of both new and old carbon to SOC across different soil depths,using a coupled carbon and nitrogen isotopic approach. The SOC turnover time for the plot receiving low N addition(250 kg·ha^(-1)·yr^(-1) N) was about 20-40 years. Conversely, the plot receiving high N(450 kg·ha^(-1)·yr^(-1) N) had a longer SOC turnover time than the low N plot, reaching about 100 years in the upper 10-20 cm layer. The rise in SOC over the entire profile with low N addition primarily resulted from an increase in the upper soil(0-40 cm)whereas with high N addition, the increase was mainly from greater SOC in the deeper soil(40-100 cm). Throughout the entire soil layer, the proportion of new organic carbon derived from maize C_4 plant sources was higher in plots treated with a low N rate than those treated with a high N rate. This implies that, in contrast to low N addition agricultural practices, high N addition predominantly enhances the soil potential for fixing SOC by transporting organic matter from surface soils to deeper layers characterized by more stable properties. This research offers a unique insight into the dynamics of deep carbon under increased N deposition, thereby aiding in the formulation of policies for soil carbon management.

关 键 词：^(13)C natural abundance nitrogen addition soil depth organic carbon turnover 

分 类 号：S153.6[农业科学—土壤学]