Strengthening the Science of Soil Health through Standardized Indicator Methods.

Identification of specific soil health (SH) constraints that impact a variety of soil resource concerns can be done with a combination of field observations and laboratory tests. While qualitative or semi-quantitative field observations can be used for preliminary identification of these concerns, identifying the specific underlying causes and management practices to address them, may require further quantitative laboratory analysis. There is a critical need for standardization of laboratory methods for measuring SH indicators. Currently SH indicators and the methods used to measure them, as well as sampling and preparation protocols, vary significantly between laboratories. There are five general soil processes or ecosystem services beyond the traditional fertility suite of measurements that are considered important for an initial set of soil indicators and methods: soil structural stability, microbial activity, bioavailable carbon, bioavailable nitrogen, and microbial community composition and diversity. For each process, we considered several indicators and methods. By standardizing methods, we will be able to compare data sets and provide consistent interpretations and recommendations. Standardization will facilitate enhanced data quality and interpretability for use in SH assessments. Without standardization, variations between methods may mask actual SH changes as well as spatial and temporal differences