Trend and network analysis to reveal disciplinary position of soil science and its sub-disciplines

Soil science, a relatively young field of research with a history of fewer than two centuries, experienced an exponential expansion in scientific output in the last decades. While the output of all sub-disciplines is growing, research efforts in these sub-disciplines differ, reflecting the importance of the subjects. The broadening focus of soil science can be detected by the content of the increasing number and diverting thematic sessions of the World Soil Science Congresses, which are held every four years since the beginning of the 20th century. The structure of the current world congress is supposed to reflect the contemporary understanding of the internal structure of soil science, including its subdivision by major themes. Considering these soil themes/sub-disciplines, we assessed the evolution of soil science in the last three decades using scientific publications as indicators. Furthermore, we evaluated the inter-linkages of soil topics within soil research using network analysis and assessed the contribution of science to the broader fields of studies, from agriculture to engineering and environmental sciences. Results show that scientific interest towards all sub-disciplines is exploding, but environment-related topics, including subjects related to climate and contamination, show an even sharper increase. As far as the internal structure of soil science is concerned, research efforts are organised around the major topics of microbiology, soil contamination, nutrients, soil physics and water management. Our study reveals that currently the highest interest towards soil is coming from ecology and environmental sciences, followed by agriculture, engineering, geology and plant sciences, respectively.