The second main challenge, which is also a research frontier, was that of scale. Several of the speakers addressed the topic, introducing the need to consider both spatial scale (from the molecular level to landscape and beyond) and temporal scale (across time and also across processes that operate at different speeds). For example, Session 2 included discussion on using microscopic and spectroscopic techniques to elucidate physical, chemical, and biological processes at the microscopic level to understand impacts at the “field scale.” Session 5, “Upscaling to a Regional Level,” considered the roles of landscape structure and remote sensing in translating soil processes from the laboratory to the field and regional scales. Both sessions addressed the issue of temporal scale. At one end of the scale, Don Sparks noted in Session 2 that there are processes that happen within nanoseconds and cannot be measured. At the other end of the spectrum, César Izaurralde and others noted that some landscape processes occur over geologic scales beyond human perception.
Scaling up of processes, rather than simply scaling up of properties, by soil scientists is particularly understudied, and soil scientists are often uncomfortable in doing so, as noted by one of the breakout groups. Soil scientists must focus on research at multiple scales ranging from nanometers to watersheds. While small-scale research is often interesting and more likely fundable, large-scale research is needed to translate small-scale research to appropriate societal and global issues. The ability to “scale down” is also needed and tractable by soil scientists. For example, the effects of global climate change on specific regions or landscapes can be translated at a scale that society and managers can understand and act on. The notion of a coordinated “grand experiment” was discussed to facilitate soil scientists in addressing the issue of scaling.