The GLBRC Switchgrass Nitrogen Rate Experiment was established in 2008 at the KBS GLBRC Intensive Field Site to examine the effects of nitrogen fertilization levels and harvest frequencies (once versus twice per year) on switchgrass productivity and greenhouse gas emissions. The experiment was established as a randomized split block design with harvest frequency comprising the split. The harvest frequency treatment was terminated in 2012, after which all plots were harvested once per year (with yields recorded separately). Eight N applications levels range from 0 to 196 kg N/ha and began in 2009. Split plots are 4.5 x 7.6 m (15 x 25′) arranged in each of 4 replicate blocks, for a total of 8 x 4 = 32 plots for each original harvest frequency treatment. A 0.5 m deep aluminum barrier now separates plots within the discontinued double harvest treatment plots (only), installed for a mycorrhizal experiment.
Lysimeters (soil water samplers) are installed in various plots.