USDA LTAR Cropland Common Experiment: Standardized primary metric protocols v1

A component of the USDA ARS Long-Term Agroecosystem Research (LTAR) network is a Common Experiment standardized across all sites. In this overview protocol we describe the development of standardized protocols for the biophysical metrics collected in the Common Experiment. Throughout this collection, we refer to “metric” as the physical sample that can be quantified and used to inform the status of performance indicators within production, environment, economic, and society domains. We refer to “protocol” as the methods used to collect that metric so that all experimental sites are compatible. This set of protocols were developed for the Cropland Sites although some are also usable for Grazingland and Integrated Common Experiment Sites. This collection allows the LTAR network to ensure research is scalable and robust. All Cropland Common Experiment Sites within the network started following these protocols with the 2024 growing season.