Stage-specific biological nitrogen fixation depends on distinct carbon and nitrogen availability in long-term fertilized paddy fields

Industrial Haber-Bosch provides 32 Tg nitrogen (N) per year to global croplands. Such large amounts of N fertilization will reshape soil N cycles. One uncertainty is whether and how these long-term N inputs impact soil biological N2 fixation (BNF) associated with plant growth, a crucial microbial-driven process to decipher the balance between soil N and plant N in paddy fields. To fill this gap, we conducted a 10-year field experiment to systematically evaluate the impacts of three N fertilization rates (0, 75, and 150 kg N ha-1) on soil BNF activity, diazotrophic communities, and environmental dynamics at two typical rice growth stages (tillering and maturation) in paddy fields. Moderate N fertilization at a 75 kg N ha-1 rate significantly stimulated BNF activity and nifH gene abundance at the tillering stage, with increases of 20.9% and 49.7%, respectively. This enhancement was primarily due to the supply of available carbon (C) sources from organic acids, which promoted the BNF proce..., , # Data from: Stage-specific biological nitrogen fixation depends on distinct carbon and nitrogen availability in long-term fertilized paddy fields

Dataset DOI: [10.5061/dryad.xwdbrv1t7](https://doi.org/10.5061/dryad.xwdbrv1t7)

## Description of the data and file structure

This dataset contains soil biological nitrogen fixation (BNF) activity, basic soil physicochemical properties, and diazotrophic community composition summarized at the phylum and genus levels. The data were generated from a long-term nitrogen fertilization field experiment in paddy fields and were used to examine stage-specific drivers of BNF across rice growth stages. All analyses presented in the associated article were based on the data provided in the three files described below.

### Files and variables

#### File: Soil_BNF_and_physicochemical_properties.csv

**Description:** Soil biological nitrogen fixation (BNF) activity and basic soil physicochemical properties for all treatments and rice growth stages.

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