# Developmental History of Soil Concepts from a Scientific Perspective
## 3 Results
### Quantitative Trends in Soil Concepts  
Soil concepts were introduced and popularized at different times. [PERSON]'s test was conducted to find the change point in the number of publications for soil concepts over time (Table 6). The test shows that all soil concepts, except for soil care and soil security, experienced statistically significant shifts in the number of citations between 1900 and 2018. Results from the Mann-Kendall test showed that all soil concepts had positive tau values (\(p\) < 0.00), indicating that the trend of citing the soil concepts overall has statistically increased. Soil care and soil security did not observe a statistically significant change point (\(p\) > 0.05). A possible reason could be the low number of publications found in the literature analysis. We found that soil care did appear in published articles at low frequency, but more prominently on websites. Soil security was introduced in soil science journals more recently, which is likely the reason that it had the lowest frequency of citations. The differences between the year when each soil concept appeared for the first time in all journals (A) and the soil science journals (B) and the change points (C) were calculated in detail (Table 7). Many soil concepts appeared in soil science journals 20 years or more after they appeared in non-soil-science journals for the first time (B-A in Table 7). Soil fertility was an exception, with a nine-year difference. Soil resilience and soil sustainability concepts had a value of zero because they appeared in soil science journals first. Many soil concepts reached their change point almost 40 years or more after appearing in all journals (C-A in Table 7). However, change points for soil quality, soil health, and soil care came almost immediately after the soil science journals published articles with those soil concepts (C-B in Table 7). The number of publications for each soil concept overall increased over time, particularly since 1990 (Figure 1). Soil concepts differed in the speeds at which their publication rates increased. Most journals experienced visibly upward trends in publications up to 2018, except for soil care. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Soil Concepts**} & \multicolumn{3}{c}{**Petttit’s Test**} & \multicolumn{3}{c}{**Mann–Kendall Test**} \\ \cline{2-7}  & **U Statistics** & \(p\)**-Value** & **Change Point (Year)** & **Kendall Score** & **Kendall’s Tau Statistic** & \(p\)**-Value** \\ \hline Soil Conservation & 3296 & <0.01 & 1967 & 4437 & 0.77 & <0.01 \\ Soil Fertility & 3203 & <0.01 & 1971 & 4462 & 0.70 & <0.01 \\ Soil Quality & 2676 & <0.01 & 1979 & 3423 & 0.69 & <0.01 \\ Soil Productivity & 2943 & <0.01 & 1981 & 3867 & 0.70 & <0.01 \\ Soil Protection & 2548 & <0.01 & 1991 & 3039 & 0.64 & <0.01 \\ Soil Sustainability & 1840 & <0.01 & 1992 & 2013 & 0.52 & <0.01 \\ Soil Health & 2208 & <0.01 & 1992 & 2478 & 0.59 & <0.01 \\ Soil Resilience & 1953 & <0.01 & 1993 & 2058 & 0.52 & <0.01 \\ Soil Care & 564 & 0.65 & 1994 & 540 & 0.25 & <0.01 \\ Soil Security & 678 & 0.39 & 2013 & 680 & 0.31 & <0.01 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Statistics summary of Pettitt’s test and Mann–Kendall test for soil concepts. Figure 1: Number of publications citing the 10 different pre-selected soil concepts over time from soil science journals (black circles with a solid black line) and all journals (orange triangle with a dashed orange line) available on the Web of Science.