The Switchgrass Nitrogen Fixation Experiment was established in 2016 after conversion of the historically tilled plots (1-16) of the KBS LTER Interactions Experiment from the annual crop rotation of the LTER Main Cropping System Experiment (MCSE) to switchgrass (Cave-in-rock). The experiment maintained the fertilizer treatments (fertilized and not fertilized) of the original interactions experiment, however, since switchgrass is a perennial crop, all plots became no-till. Although the tillage treatment was discontinued in 2016, the tillage treatment legacy is depicted on the plot map. From 2018-2022, a rainout shelter experiment that also used buried mesocosms was conducted in the historically no-till, no fertilizer plots (3, 6, 8, 9) to examine the effect of soil wetting/drying regimes on the relationship between associative nitrogen fixation (ANF) and switchgrass phenology, diazotroph communities, and nifH expression. The Switchgrass Nitrogen Fixation Experiment was retired after the 2022 growing season when switchgrass was terminated in spring 2023 in order to establish the Switchgrass Biodiversity Experiment.
Maps: