The Natural Capital of Soils and the Contributions Soil Physics Must Make.

The unknown consequences and potential impacts of mankind’s ability to destroy, alter or manipulate ecosystems on a vast scale drives our need to better understand the earth system. Soil physics has important contributions to make toward this goal. A fundamental challenge for soil science in the 21^st century is to understand the role of soil processes in relation to the function of the earth system. Natural Capital and Ecosystem Services are concepts developed in ecology based on the premise that we value 'things' based on their perceived value to human well-being. As a consequence, ignorance of the value of a resource, or system, may lead to its neglect and omission from policy decision making. Therefore, there is a need to develop a comprehensive definition of soil natural capital, fitting within a broad framework, which can be used to assess the stocks and services that contribute to the function of the earth system.
            Though various definitions of soil natural capital have been proposed, it still remains a nebulous and ill-defined term. This talk gives an overview on a new definition of soil ‘natural capital’ focusing on 1) mass, 2) energy and 3) organization/entropy. Mass is further subdivided into solid, liquid and gas phases, and organization into physico-chemical, biotic and spatio-temporal structure. We differentiate between two aspects of capital, the quantity and the quality. As a result of our definition, soil moisture, temperature and structure emerge as valuable stocks, alongside the more traditionally viewed stocks such as inorganic (mineralogy, texture) and organic materials (OM content).