The list in Table 2 and Figure 3 provides a snapshot of the most prolific authors in the field of biochar research. Each of these researchers has made significant publications, as demonstrated by the large number of papers they've published on the subject. At the top of the list is Yong Sik Ok from Korea University, who has an impressive count of 535 publications. Following Ok is Dan Tsang from Hongkong Polytechnic University with 269 publications, and Hailong Wang from Foshan University with 222 papers.
The remaining authors, including Joerg Rinklebe from Wuppertal in Germany, Bin Gao from University of Florida, Nanthi Sirangie Bolan from University in Western Australia, and others, have each published over 100 papers, underlining their active roles in publishing biochar research.
The results are in line with previous bibliometric studies who hailed Yong Sik Ok as the most prolific researcher in Biochar followed by Gao Bin and Dan Tsang (Abdeljaoued et al. 2020; Li et al. 2020).  Qin et al. (2022) already revealed closely collaborating clusters of authors with strong subgroup connections, with Yong Sik Ok, Daniel C.W. Tsang and Bin Gao at their core. It's worth noting that the presence of these authors with high publication counts indicates a concentrated effort by a group of collaborating researchers in this field.  
 

Highly cited authors

Table 2 lists profilic  authors who have published more than 10 highly cited papers on biochar. Highly cited papers are scientific papers that have received a large number of citations from other papers in the scientific literature or top 1% based on the number of citations received when compared to other papers published in the same field in the same year. They are from the last 10 years of publications (from 2013 to April 2023).
 
Table 2. Profilic  authors who have published more than 10 highly cited papers (HCP) on biochar based on Web of Science.
Author Affiliation HCP Group
Ok, Yong Sik Korea University, Korea 92 Ok
Tsang, Dan Hongkong Polytechnic, China 66 Tsang
Gao, Bin University of Florida, USA 46 Gao
Rinklebe, Joerg Wuppertal University, Germany 46 Ok
Zeng, Guangming Hunan University, china 46 Zeng
Bolan, Nanthi Sirangie University of Western Australia, Australia 31 Ok
Wang, Hailong Foshan University, China 28 Ok
Tan, Xiaofei Hunan University, china 19 Zeng
Shaheen, Sabry M. Kafrelsheikh University, Egypt 19 Ok
Zhang, Chen Hunan University, china 17 Zeng
Cao, Xinde Shanghai Jiao Tong University 16 Ok, Gap
Huang, Danlian Hunan University, china 16 Ok
Zhang, Zengqiang Northwest A&F University - China 14 Ok
Hou, Deyi Tsinghua University 14 Ok
Tao, sun Korea University, Korea 14 Ok
Lai, Cui Hunan University, china 13 Zeng
Cheng, min Hunan University, china 13 Zeng
Zimmerman, Andrew R. University of Florida, USA 13 Gao
Sun, Yuqing Sun Yat Sen University 13 Tsang
Lam, Su Shiung Universiti Malaysia Terengganu, Malaysia 12 Ok
Ali, Shafaqat China Medical University (Taiwan) 12 Ok
Vithanage, Meththika University Sri Jayewardenepura, Si Lanka 12 Ok
Rizwan, Muhammad Government College University Faisalabad 12 Ok
Wang, Shengsen Yangzhou University 11 Gao, Ok
Ye, Shujing Guangxi University 11 Zeng
Sarkar, Binoy University of South Australia 11 Ok
 
 Yong Sik Ok tops the list with a remarkable 92 highly cited papers, further solidifying his position as a leading figure in biochar publication. Following Ok, Dan Tsang with 66 highly cited papers and Bin Gao, Joerg Rinklebe, and Guangming Zeng, each with 46 highly cited papers, have also made substantial contributions to the field that have resonated with their peers.
Even authors toward the bottom of the list from the third world countries, such as Su Shiung Lam from Malaysia, Shafaqat Ali from China, Meththika Vithanage from Sri Lanka, and Muhammad Rizwan from Pakistan, each with 12 highly cited papers, have made to the citations list. The high citation counts indicate that these authors' work is not only prolific but also of highly cited by others. Johannes Lehmann, the biochar expert from Cornell, hailed as a top scientist was dethroned by Yong Sik Ok in terms of highly cited paper (Kumar et al. 2023).
Additionally, this study conducts a network analysis of co-authorship among the authors of highly cited papers. The findings using VOSviewer, presented in Figure 4 using VosViewer analysis, indicate that with there were 4 main groups of researchers dominating the highly cited papers. They are:
(1)   Red group led by Yong Sik Ok from Korea University
(2)   Purple group led by Dan Tsang from Hongkong Polytechnic
(3)   Yellow group led by Gao Bin from Florida University
(4)   Green group led by Guangming Zeng from Hunan  University
A small Blue group led by Yauyu Zhou from  Hunan Agricultural University is actually in the Green group.