Aware and add missing concepts to the knowledge graph

[wbcbugfree]

As mentioned in the EEA's soil monitoring report, the report does not cover all main soil threats, e.g., wind erosion and salinization. So we need other (peer-reviewed) literature to complement these aspects.
Even more problematic is the fact that the aspects that are discussed in the report may not be in-depth, which means that the report does not (and is unlikely to) cover all of the key concepts under the topic of soil health. For instance, active carbon, also known as permanganate-oxidizable carbon (POXC), is a portion of soil organic carbon. Soil organic carbon is a very important factor of soil health and is discussed in reports, but these discussions do not address POXC. This is just one concept that we are aware of and believe that similar situations exist in other aspects. So we may need a mechanism to help us identify the missing concepts and add them to the knowledge graph. We also need some filtered literature for those missing concepts as the knowledge source for the knowledge graph.