The evolution of Journal Impact Factors and related scientific output in Soil Science (1997–2022)

Abstract

The Journal Impact Factor (JIF), calculated as the number of citations received by an indexed journal in a specific year, divided by the number of citable items (articles) published in the previous two years, is the most used bibliometric index across multiple scientific disciplines. There is a general perception about the growth in JIFs and scientific output (number of journals, authors, articles and citations) across most disciplines during the last decades, but the actual numbers are not widely known. Here, we assessed the evolution of JIFs, and data used in their calculation, during a 26-yrs interval in Soil Science, either as averages, or as actual data for some selected journals. Data for the area of Agronomy were also compiled, due to its affinity to Soil Science, as a meaningful comparison. Between 1997 and 2022, the number of indexed Soil Science journals grew from 24 to 45 (ca. 87%), whereas the number of articles and citations increased, respectively, from 2,158 to 6,346 (+194%) and 41,890 to 395,115 (+843%). In consequence, the average JIF for Soil Science increased from 0.788 to 3.578 (+354%). Such growth was higher than for Agronomy, which varied from 0.724 to 1.999 (+176%) in the same period, despite this area presenting a much larger output in number of journals, articles and citations. Some of the highest JIF growth rates in Soil Science occurred for traditional journals published by commercial scientific publishers, whereas non-profit journals maintained by scientific societies presented a much lower but still relevant growth rate. Finally, even when the highest JIFs were not ascribed to traditional Soil Science journals, their bibliometric footprint – understood as a combination of the number of articles published and the total number of cites – were clearly more indicative of relevance and leadership in the discipline than the JIF itself.