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

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

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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.yr1 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 C4 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.

13C natural abundancenitrogen additionsoil depthorganic carbon turnover

Hualing HU、Liang ZHAO、Wenbing TAN、Guoan WANG、Beidou XI

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Technical Centre for Soil,Agriculture and Rural Ecology and Environment,Ministry of Ecology and Environment,Beijing 100012,China

State Key Laboratory of Environmental Criteria and Risk Assessment,Chinese Research Academy of Environmental Sciences,Beijing 100012,China

College of Resources and Environmental Sciences,China Agricultural University,Beijing 100193,China

2024

10.15302/J-FASE-2024565

农业科学与工程前沿(英文版)

农业科学与工程前沿(英文版)

ISSN：
年,卷(期)：2024.11(2)