This dataset contains data for exploring the legacy effects of biochar addition on soil nitrous oxide emissions and their effects on functional gene abundance associated with soil nitrogen cycling. The dataset contains two data files, one is a data table on the impact of biochar application on soil nitrous oxide emissions, which contains the coordinates of the study site, climate, basic physical and chemical properties of the soil, biochar characteristics and study duration, crop type and management. The other is the data table on the effect of biochar application on the abundance of functional genes related to soil nitrogen cycling, which contains information such as test site coordinates, climate, biochar characteristics, crop type and management. This data can be referenced and reused without any legal or ethical considerations.

We compiled and updated the datasets of several existing meta-analysis studies. The literature collection cut-off date is March 2022. Our database contained only field and pot studies and excluded laboratory incubation experiments because of its underrepresentation of in situ environments. In addition, we referred to the search terms and screening criteria used in previous meta-analyses when updating the literature. In total, we obtained 747 pairs of observations from 96 articles, of which 398 were for N₂O emissions, 166 were for genes related to ammonia oxidation processes, and 183 were for genes related to denitrification processes.