Introducing SOils DAta Harmonization tools (SoDaH)

Coordinated activities and network science are expanding the scope and breadth of information measured across sites. Wrapping these initiatives into combined databases presents opportunities to deepen our general understanding of ecological processes, specifically related to factors controlling the persistence and vulnerability of soil organic matter. Here we present an open-source set of tools than can be used to harmonize diverse soil datasets. Specifically, we used SoDaH to harmonize data from the Long-Term Ecological Research Network (LTER), Critical Zone Observatory (CZO), National Ecological Observatory Network (NEON), Detritus Input and Removal Treatments (DIRT), and Nutrient Network (NutNet). The perspectives and historical legacies of each network afford distinct insights into understanding aspects of SOM dynamics. For example: LTER, DIRT, and NutNet sites generally contribute long-term datasets focusing on ecosystem responses to manipulative experiments (especially for surface soils); meanwhile CZO sites tend to contribute more information on soil mineralogical properties and a focus on deeper soil horizons; finally, NEON contributes standardized data collection procedures that span continental-scale edaphic and ecoclimatic gradients. Our team created SoDaH to bring these diverse data streams together into a harmonized dataset that can be used for synthesis activities and model development. The R package, that is publicly available, includes tools to read and harmonize user-provided raw data that is mapped to a template with controlled vocabulary and standard units. We also provide a suite of QC tools, additional notes associated with each harmonized dataset, a function that can re-harmonize the entire database when additional information is provided, as well as sample scripts that can be used to query the database. Moving forward we encourage further contributions to the database and use of the harmonized data product for synthesis and modeling studies.