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

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, wepresent the technical details and the performance of the JKI-FACE facility based on thee-year data (2022–2024) regardingtemporal and spatial carbon dioxide distribution. Our results indicated that high-frequency (1-min) data of CO 2 concentra-tion was within 10% and 20% of the target concentration (600 ppm) for 84.2% and 95.8% of the time, respectively. Althoughthe rings are relatively close together in our experimental setup, CO 2 drift measurements suggest no significant interferencebetween the rings. These results suggest that JKI-FACE is a suitable field infrastructure for studying the effects of increasingCO 2 concentrations in cereals. With this FACE facility, we focus on the intraspecific variation of the response of crop yieldand quality to elevated CO 2 to make an important contribution to the adaptation of crops and cropping systems to changingclimate conditions