Switchgrass harvest time management can impact biomass yield and nutrient content

Authors: Serapiglia, Michelle; Boateng, Akwasi; LEE, D - University Of Illinois; Casler, Michael

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2016
Publication Date: 4/29/2016
Publication URL: http://handle.nal.usda.gov/10113/62424
Citation: Serapiglia, M., Boateng, A.A., Lee, D.K., Casler, M.D. 2016. Switchgrass harvest time management can impact biomass yield and nutrient content. Crop Science. 56:1-11.

Interpretive Summary: Switchgrass is a major energy crop native to much of North America. While high-biomass yield is of significant importance for the development of switchgrass as a bioenergy crop, nutrient content in the biomass as it relates to biofuel conversion efficiency is also critically important for sustainable energy production. In order to evaluate biomass yield and nutrient uptake/cycling in switchgrass, replicated trials across three sites in the mid-west were established in 2009. The switchgrass were harvested once annually at peak crop, after killing frost, or post-winter in the spring for each growing season. Switchgrass biomass yield was greatest at the peak crop harvest with biomass decreasing as harvest was delayed. Similarly, nutrient content was greatest in the biomass at the peak crop harvest. The results show that the majority of the N, P and K removed from the soil and accumulated in above-ground biomass was relocated to belowground storage in the post-frost harvest in October. The lower levels of nutrient content and total ash content in the biomass at the post-harvest biomass are beneficial for the sustainability of the switchgrass crop and for downstream conversion processes to bioenergy. Harvesting post-frost can be advantageous to switchgrass producers to improve biomass yield and quality for sustainable bioenergy production.

Technical Abstract: Switchgrass (Panicum virgatum L.) is a dedicated energy crop native to much of North America. While high-biomass yield is of significant importance for the development of switchgrass as a bioenergy crop, nutrient content in the biomass as it relates to biofuel conversion efficiency is also critically important for sustainable energy production. In order to evaluate biomass yield and nutrient uptake/cycling in switchgrass cultivars, replicated trials across three sites, Arlington, WI, Marshfield, WI, and Urbana, IL, were established in 2009. The switchgrass cultivars were harvested once annually at peak crop, after killing frost, or post-winter in the spring for each growing season. Switchgrass biomass yield was greatest at the peak crop harvest averaging 9.9 Mg ha-1 with biomass decreasing as harvest was delayed. Similarly, nutrient content was greatest in the biomass at the peak crop harvest with N, P, K removal at 69, 77, and 23 kg ha-1, respectively. The results show that the majority of the N, P and K removed from the soil and accumulated in above-ground biomass was relocated to belowground storage in the post-frost harvest in October. The lower levels of nutrient content and total ash content in the biomass at the post-harvest biomass are beneficial for the sustainability of the switchgrass crop and for downstream conversion processes to bioenergy.