Moving Toward a Common Core of Soil Health Indicator Methods.

As protocols for soil health assessment move beyond measurements currently associated with standard soil testing for fertility evaluations and fertilizer recommendations, it is increasingly important to determine how chemical, physical and biological components of the soil system are interacting and if a specific type of soil is functioning at its fullest potential for the desired use (i.e., productivity, filtering and buffering, waste remediation, structural stability, etc.). As discussed previously in this session, the concept of soil health is not new, but during the past five years there has been a tremendous increase in public awareness of soil health and its importance, led in part by the Soil Renaissance project (a multi-organizational effort initiated by the Noble and Farm Foundations). One major outcome of that project has been a coordinated effort to develop a common set of standardized soil health indicator methods that can be used by public and private laboratories to quantitatively assess soil health. This effort has involved close to one hundred people from universities, USDA/ARS and NRCS, non-governmental organizations, and commercial soil testing laboratories. Several critical soil processes or functions including soil organic matter cycling, nutrient availability, chemical reactivity, water infiltration, root penetration, microbial activity (respiration and enzyme activity), microbial community structure, microbial food source quality, and bioavailable nitrogen were targeted as critical initial indicators for assessment. Methods chosen through consensus among participants representing the multi-organizational teams and agreed upon as being the best currently available indicators were based on several interacting criteria. This included ease of use by soil testing laboratories, sensitivity to changes in agricultural management practices, ability to detect short-term changes, repeatability, and representation of diverse processes of agronomic and environmental relevance. Furthermore, it was agreed that one of the next steps would be to develop a process to allow for changes to the core methodologies as new and improved measurements and tools become available. To prevent the perfect from derailing the good, the core methods will be used for an upcoming national soil health assessment (NSHA) that will be conducted jointly by the Soil Health Institute and the Noble Foundation. The recommended indicators and their measurement protocols will also be made available to the public through publication of a methods manual. These will also be used, at least initially, by the USDA/NRCS efforts to monitor and assess soil health over time and thus contribute to improved conservation planning.