Physical Soil Health Indicators

Soil health as capacity of soil to function as a vital living ecosystem and providing various services for terrestrial systems is endangered by intense land use and climate change. To assess the sol health status and its evolution of the time, adequate soil health indicators must be defined and quantified.
Healthy soils sustaining an intact ecosystem contain structural pores. Physical soil health indicators must be (i) sensitive to the presence of structures, (ii) relevant for the ecological processes in soils, (iii) integrate various soil hydraulic properties, and (iv) should be quantifiable at different scales. We propose characteristic times for the following processes as new physical indicators of soil health: ponding time limiting water infiltration, attainment of field capacity, and evaporative phase transition. These characteristic times can be measured in the field, predicted from soil hydraulic properties, and have the potential to be deduced from satellite data at national and global scale. These times are also sensitive to structure formation and structural properties that are important for chemical and biological soil health (soil organic content).