The benefit of soil free-living N2 fixation to grassland primary productivity is suppressed by nitrogen enrichment: NH4+–N:NO3––N ratios matter

Data_Description.csv Includes detailed explanations of the research context and initial parameters for the raw datasets.Initial data Folder Contains the original measurements and initial data files as recorded prior to any statistical processing.Figure_data Folder Consists of processed data that has undergone cleaning, aggregation, and mathematical transformation for figure generation.Code_lijuanliu2026.R Provides the complete source code used to perform data analysis and generate all publication-quality graphics.