Biochar modulation of the soil nitrogen cycle: a Cite Space-based bibliometric study

To identify proactive areas in biochar modulation of the soil nitrogen cycle, Cite Space was applied to Web of Science and CNKI, to analyze total number of publications, countries of origin, author home institution, highly-cited authors and keywords, from 1998-2019．The total number of articles in both Chinese and foreign languages gradually increased, those in foreign languages increased at a higher rate．Most published papers were found to be from China and the United States, but the latter showed a high proportion in top 20 (TOP20) highly cited papers．Top institutions with most published articles written in Chinese include Henan Agricultural University, Shanxi Academy of Agricultural Sciences, and Chinese Academy of Agricultural Sciences．Of the 10 top institutions with the most numerous articles published in international journals, seven were located in China．However, author group analysis revealed limited academic exchange among different research groups．Analysis of keyword clustering and burst terms identified research areas that will need to be addressed more extensively in the future: soil quality improvement by biochar, biochar modulation of soil nitrogen cycling (mineralization, nitrification and denitrification), and nitrogen cycle-related microbe modulation of biochar addition．