Experimental Design and Performance of a Free Air Carbon Dioxide Enrichment Facility in Northern Germany

ABSTRACT Free air carbon dioxide enrichment (FACE) offers a unique approach to study the response of crops to rising carbon dioxide (CO 2 ) concentrations under field conditions. We have established a Miglietta‐type FACE facility in Northern Germany (JKI‐FACE) consisting of four rings with CO 2 fumigation and four rings without fumigation with diameters of 15.5 m. Here, we present the technical details and the performance of the JKI‐FACE facility based on thee‐year data (2022–2024) regarding temporal and spatial carbon dioxide distribution. Our results indicated that high‐frequency (1‐min) data of CO 2 concentration was within 10% and 20% of the target concentration (600 ppm) for 84.2% and 95.8% of the time, respectively. Although the rings are relatively close together in our experimental setup, CO 2 drift measurements suggest no significant interference between the rings. These results suggest that JKI‐FACE is a suitable field infrastructure for studying the effects of increasing CO 2 concentrations in cereals. With this FACE facility, we focus on the intraspecific variation of the response of crop yield and quality to elevated CO 2 to make an important contribution to the adaptation of crops and cropping systems to changing climate conditions.