Grazing-N addition interactions drive soil carbon priming and balance via bacterial assimilation in a meadow steppe
Data files
Oct 13, 2025 version files 212.62 KB
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Priming_effect_data.csv
56 KB
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Priming_effect_data.xlsx
148.87 KB
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README.md
4.26 KB
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Wangcl_et_al_data.csv
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Abstract
Grassland carbon storage depends on microbial-mediated interactions between grazing and nitrogen (N) addition, which regulates the balance between soil organic carbon (SOC) retention and priming effects. However, uncertainties regarding these interactive mechanisms constrain projections of SOC vulnerability under global change.
We conducted a factorial field experiment involving grazing and N addition in a Leymus chinensis meadow in northeastern China. In the fifth year of the experiment, we collected soil to conduct a 70-day soil incubation combined with labile carbon (glucose) addition to examine the effects of the grazing and N addition treatments soil carbon priming and carbon retention.
Grazing consistently increased priming effects regardless of N addition. In contrast, N addition strongly reduced priming by 41.0% in ungrazed plots but had minimal increase effects (3.2%) under grazing. Mechanistically, bacterial glucose assimilation capacity primarily mediated grazing-dependent N effects on priming, explaining 65.0% of the variation and correlating positively with priming intensity. Grazing notably decreased the net SOC balance (35.7 mg kg-1 soil) and diminished the beneficial effect of N addition on SOC (+79.6% in ungrazed vs. +12.3% in grazed plots). Priming effects and bacterial glucose assimilation were dominant drivers of SOC responses under grazing, exhibiting negative correlations with net SOC balance.
Synthesis and applications: Our results show that grazing-induced bacterial dominance in carbon assimilation alters priming effects and net soil carbon balance under N addition, offsetting potential carbon sequestration benefits by accelerating native organic matter decomposition. Thus, microbial carbon assimilation capacity, particularly bacterial substrate assimilation, may serve as an indicator of SOC vulnerability under global change.
Dataset DOI: 10.5061/dryad.w9ghx3g21
Description of the data and file structure
This dataset focuses on the soil priming effect and associated microbial dynamics under different grazing and nitrogen (N) addition treatments. It includes raw measurement data, derived ecological indices, and R code for data analysis, enabling the exploration of how grazing disturbance and N input regulate soil organic carbon (SOC) cycling and microbial activity.
Files and variables
File: Wangcl_et_al_data.csv
Description: Derived summary data of soil properties, microbial traits, and ecosystem C balance. Integrates key indices from the raw data (e.g., priming effect percentage, microbial carbon use efficiency) and additional measurements (e.g., soil enzyme activity, biomass, pH).
Variables
- Summarizes treatment-level averages of soil and ecosystem traits:
- Soil organic carbon (mg kg⁻¹ soil): Total SOC content.
- The contributions of microbial necromass carbon to soil organic (%): Percentage of SOC derived from microbial necromass carbon.
- Net SOC balance (mg kg⁻¹ soil): Net change in SOC storage (sequestration minus loss), reflecting ecosystem C sink/source status.
- Root:shoot ratio: Ratio of root biomass to aboveground biomass, indicating plant allocation to belowground C.
File: Priming_effect_data.csv
Description: Raw time-series data of soil microbial respiration and carbon (C) isotope dynamics under glucose addition (to induce priming effect) and no-glucose control. Includes measurements across 70 days of incubation, covering multiple treatment combinations (grazed/ungrazed, N addition/no N addition).
Variables
- All variables include units of measure in their headers. Key variables are highlighted below:
- ID: Unique identifier for each sample replicate (e.g., CK1, G1, N1).
- Treatments of grazing: Grazing status of the sample (Ungrazed = no livestock grazing; Grazed = livestock grazing).
- Nitrogen Addition Treatments: N input status (No N addition = no external N; N addition = external N added).
- ti: sampling time after add Glucose（Day）: Time point (in days) after glucose addition (0, 1, 2, 3, 4, 5, 6, 7, 14, 28, 42, 70).
- δ¹³CO₂ at ti: Carbon isotope ratio of respired CO₂ (per mil, ‰), used to distinguish C from glucose vs. native SOC.
- Microbial respiration rate at ti: Multiple units (e.g., μg CO₂ h⁻¹, μg C g⁻¹ soil h⁻¹) to reflect respiration intensity per unit volume, soil mass, or C.
- Priming effect from 0 to ti (%): The priming effect accumulated from the start of incubation (0 days) to time ti.
Priming_effect_data.xlsx is also provided to preserve heading formatting.
File: Calculation code in R.docx
Description: R code script for processing, analyzing, and visualizing the dataset. Includes steps for descriptive statistics, ANOVA, correlation analysis, and linear regression modeling to quantify relationships between variables.
Variables
- No variables (code-only). Key functions include:
- read_csv(): Import CSV files and handle missing values.
- aov(): Conduct analysis of variance (ANOVA) to test treatment effects.
- cor()/corrplot(): Calculate and visualize correlations between variables.
- lm(): Build linear regression models to quantify drivers of priming effect and SOC balance.
Missing Value Codes
n/a: Indicates not applicable. These occur in:
- Priming effect data.csv: Rows where cumulative values (e.g., Total amount of released soil carbon during ti to ti+1) cannot be calculated (e.g., at ti = 0 days, no prior time point exists to compute a "ti to ti+1" interval).
- Columns for 70-day cumulative data (e.g., The cumulative of released soil carbon from 0 to ti) where ti = 70 days (no subsequent time point to finalize the cumulative sum).
Rationale for Missing Data
Missing values are not due to measurement errors but to logical constraints or mathematical limitations. All missing values are consistent across treatment groups and do not bias the dataset.