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OSU Central Analytical Laboratory Soil Health Testing
Soil health has been defined as the "the continued capacity of soil to function as a vital living system, within ecosystem and land-use boundaries, to sustain biological productivity, promote the quality of air and water environments, and maintain plant, animal, and human health"
CAL is focused on providing Soil Health analyses using academically rigorous methods in accordance with various organizations that are working to advance the science. We have an educational project with the OR National Resources Conservation Service to allow our lab to participate in the development of a set of nationally adopted soil health metrics. We process samples for producers and researchers and are developing a soil health database to use as a tool to encourage producers to focus on how their land management may affect soil health.
The standard suite of tests available in our "Soil Health Package" are: pH, EC, total C and N, NO3-N, P, K, Mg, Ca, texture, potentially mineralizable nitrogen, active carbon, water stable aggregates, CO2 burst respiration, available water holding capacity, and moisture. We are not currently providing a soil healh score but are working on regionally appropriate metrics to help producers interpret the results.
For most of our agriculturally based soils analyses the focus has been on the chemical nutrients present in the soil in order to give a fertilizer application recommendation. While the nutrients available to the plant absolutely impact the overall productivity of the land, this focus has neglected the biological processes that maintain the soil functions and the long term capacity of the soil to sustain productivity. As we learn more about the ideal conditions for the function of biological communities in the soil we can get to the underlying mechanisms that maintain long term sustainable soil and plant productivity. The new focus on soil health uses parameters such as aggregate stability, active carbon, and potentially mineralizable nitrogen. Aggregate stability measurements give us a better idea about the spaces in the soil where the microbes function, water moves, and plants get their nutrients. Active carbon can tell us about the carbon in the soil available for the microbes to use for energy in order to carry out nutrient transformations. Potentially mineralizable nitrogen quantifies the microbial transformations of soil organic nitrogen to plant available nitrogen, nitrate and ammonium. As we continue to work with partners around the country we will adopt and develop a full set of metrics to analyze the health of soil systems.
Further resources for those interested in soil health:
Definitions of Soil Health from the Food and Agriculture Organization of the United Nations
A quick video from NRCS on soil health with Dr. Ray Weil
A 139 page report from the 2008 FAO International meeting titled: An international technical workshop, Investing in sustainable crop intensification, The case for improving soil health
Soil health has been defined as the "the continued capacity of soil to function as a vital living system, within ecosystem and land-use boundaries, to sustain biological productivity, promote the quality of air and water environments, and maintain plant, animal, and human health" (Pankhurst et al., 1997).
Two elements in this definition of soil health distinguish it from the definition of soil quality: (i) the inclusion of a time component (e.g. ''the continued capacity of'' - reflecting the importance of the soil in being able to continue to function over time); and (ii) recognition of soil "as a vital living system" (emphasizing the importance of the soil biota to soil functioning).
Building on this definition of Pankhurst and co-authors, members of an international workshop at FAO, have come up with this definition:
"Soil health is the capacity of soil to function as a living system, with ecosystem and land use boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and promote plant and animal health. Healthy soils maintain a diverse community of soil organisms that help to control plant disease, insect and weed pests, form beneficial symbiotic associations with plant roots; recycle essential plant nutrients; improve soil structure with positive repercussions for soil water and nutrient holding capacity, and ultimately improve crop production" (FAO, 2008).
To this definition one might want to add an ecosystem perspective: A healthy soil does not pollute its environment and does contribute to mitigating climate change by maintaining or increasing its carbon content.
The concept of soil health captures the ecological attributes of the soil, which have implications beyond its quality or capacity to produce a particular crop. These attributes are chiefly those associated with the soil biota; its biodiversity, its food web structure, its activity and the range of functions it performs. For example, soil biodiversity is not necessarily a soil property that is critical for the production of a given crop, but it is a property that may be important for the continued capacity of the soil to produce that crop.
FAO 2008. An international technical workshop Investing in sustainable crop intensification The case for improving soil health. Integrated Crop Management Vol.6-2008. FAO, Rome: 22-24 July 2008