The LTAR Common Experiment: Vision, Framework and Status.

Long-term research is essential to evaluate the efficacy of management to achieve sustainable intensification goals. Such research should provide a mechanistic understanding of the underlying processes affecting ecosystem services, be scalable to provide useful predictions for a range of management scenarios, and be translated in such a way that it effectively supports both adoption of best practices/systems by producers and informed decision making by policymakers. In response to these needs, the Long-term Agroecosystem Research (LTAR) network includes a Common Experiment in its portfolio of coordinated research activities. Objectives of the LTAR Common Experiment include: 1) Develop and evaluate production systems that increase production and/or reduce use of resources while enhancing delivery of ecosystem services, 2) Employ a coordinated array of ecosystem service measurements, 3) Identify, quantify, and understand mechanisms underlying tradeoffs and synergies among ecosystem services, and 4) Use long-term measurements and experimental observations to model ecosystem service outcomes under future projections of climate variability and change in order to develop management recommendations for adapting to these changes. Comprising both cropland and rangeland sites across the U.S., the Common Experiment will include long-term observations of production and site-selected ecosystem services. To maximize participation, longevity, and comparability, the Common Experiment uses a simple design, contrasting ‘Business as Usual’ and ‘Aspirational’ treatments over a 30-year timeline at two scales (plot and field). To maintain relevance, treatments will be periodically revisited and adjusted based on adoption rates, new technology/innovation, and socioeconomic change. Deployment of the Common Experiment is site-specific, aligning with available resources, land access, and on-site personnel. Accordingly, starting times, measurement scales, and design features of the Common Experiment are tailored to site realities – that in aggregate – represent a mosaic of research efforts collectively addressing critical issues of agricultural sustainability.