An analysis on research trend of soil aggregates based on CNKI in the past 30 years

In order to analyze the research progress on soil aggregates published in Chinese journals, the advanced retrieval function of China National Knowledge Infrastructure (CNKI) was employed to retrieve related topics from 1990 to 2019.Bibliometric analysis was conducted using the metrology visual analysis function of CNKI.According to the number of publications, the research progress of soil aggregates was divided into two stages: the slow development stage from 1990 to 2004 and the rapid development stage from 2005 to 2019.According to the published papers, Northwest A&F University and Nanjing Agricultural University were with strong research forces in the field of soil aggregates.The institutes of the Chinese Academy of Sciences (CAS) were with the highest average citation rate, indicating a relatively higher research level.The analysis of related research subjects and keywords of soil aggregates found that soil organic matter, soil fertility, agronomic practices and soil physical property were the important subjects in soil aggregates research, which showed a rapid increase trend.This trend was consistent with the core research content based on the bibliometric analysis of Web of Sciences.However, studies concerning influences of land use and soil erosion on soil aggregates showed a decline trend in recent years.Notably, the study of soil improvement and soil microorganisms presented an explosive growth in 2015-2019.In general, the research of soil organic matter/carbon remains the most important subject.Meanwhile, researches on soil aggregates related to environment and ecological science have been popular, and soil improvement and biological processes involved in soil aggregation have been a new hotspot.