Long-Term Field Experiments Overview Map: An interactive open-access metadata platform to enhance networking and data reuse

• LTE-Map offers open-access to global metadata on long-term experiments, enabling discovery and reuse. • It consolidates metadata from 688 LTEs, with 82% related to arable land practices. • Access to FAIR LTE (meta)data for researchers and practitioners is promoted. • Regular updates ensure trial status tracking, supporting collaboration among agricultural LTE holders. Agricultural long-term experiments (LTEs) are infrastructures for understanding the long-term impacts of agricultural practices on soil health, crop productivity, and environmental sustainability. Some spanning over 150 years, they generate essential data on crops, fertilization, tillage, irrigation, and land management. However, the fragmented landscape of LTEs leading to data accessibility challenges have limited their full research potential. We introduce an overview map for LTEs (LTE-Map) (https://lte.bonares.de) , an open-access and interactive platform that centralizes and provide valuable information (metadata) from LTEs. Developed with LTE institutions and data users, its structured model standardizes experimental and organizational data for global interoperability. It enables researchers to efficiently access LTE metadata, aligning with FAIR principles, and serves as a user-friendly gateway to key experimental and environmental information. Currently, the LTE-Map documents 688 trials globally including the earliest experiment established in 1843. While most sites are in Europe (621), more than 60 are located outside, underlining the potential for global expansion. The map shows that LTEs are predominantly focused on arable land and crop rotation studies. The LTE-Map provides a flexible framework for exploring trials, supporting both data providers and researchers based on relevant criteria. It stands as a cornerstone of data management, fosters collaboration and reuse, and has already enabled multiple studies, demonstrating its value as proof of concept for advancing experimental research.