Nitrogen fertilization, yield components, and species selection of perennial grass bioenergy cropping systems across eastern North America

Biomass;Bioenergy;Perennial grass;Miscanthus;Switchgrass;Prairie

Wycislo, Andrew Paul

关键词: Biomass;    Bioenergy;    Perennial grass;    Miscanthus;    Switchgrass;    Prairie;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/95439/WYCISLO-DISSERTATION-2016.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Perennial grasses are being studied as a fuel source and potential replacement for fossil fuels.Perennial grasses are a versatile group of potential bioenergy crops that have the ability to produce large yields on relatively low-quality land or with lower inputs than traditional annual row crops such as maize.Grasses can be directly combusted to produce heat and/or electricity or can be processed to produce cellulosic ethanol similarly to corn grain ethanol that is combined with gasoline for use as a liquid transportation fuel.Miscanthus x giganteus (Miscanthus), Panicum virgatum (switchgrass), and recreated, multi-species tallgrass prairies are possible perennial systems for high-yield production in crop-growing regions of North America.However, past research has reported mixed findings regarding species selection and responses of perennial energy crops to nitrogen fertilization.This dissertation examines several of these aspects in three studies:1) An in-depth look at the effects of N fertility rates on biomass yield and individual yield components of Miscanthus across several seasons.Results demonstrated that applying 60 or 120 kg N ha-1 provides a 2x yield increase compared to unfertilized Miscanthus in a long-term study at Urbana, IL, USA.Total tillers per m2 were strongly correlated with increasing biomass yield, with tiller height, diameter, and phytomer number also correlating well with yield.2) The productivity of side-by-side plots of Miscanthus and switchgrass was evaluated over two years in 11 locations in eastern North America.Results showed Miscanthus to be a greater producer of biomass than switchgrass across all sites, and showed variability among sites on the effect of applied nitrogen fertilizer.Most yield components were correlated with yield changes, but in some cases were affected differently by added fertility.Overall, proper selection of species or switchgrass cultivar played a role in biomass production at a given site.3) A long-term field-scale comparison of three perennial grass systems: Miscanthus, switchgrass, and a high-diversity recreated tallgrass prairie.Monoculture stands of Miscanthus and switchgrass produced more biomass than the prairie system while the stands were young, but yields of monoculture crops declined with stand age.The monoculture stands produced more biomass than the prairie stand during the drought year of 2012, indicating that diverse systems are not necessarily more resistant to drought.Application of nitrogen fertilizer to declining Miscanthus stands starting in year six generated a nearly 2x yield increase over unfertilized plots, which still produced more biomass than the prairie.In addition, average annual energy production was greater in switchgrass and Miscanthus stands than in a corn-corn-soybean rotation system, due to the inconsistency of corn yields and the low energy potential of soybean.Finally, as a sidebar, harvest results using a plot-scale combine and a commercial harvest system were strongly correlated, which indicates that the plot-scale combine is a good estimator of overall yields.These results show that applied nitrogen fertilizer increases yields of bioenergy crops in certain situations, and measuring certain yield components may provide a good estimate of total biomass yield.Perennial grass systems are at least comparable to annual row-crop systems, and in many cases may exceed them in overall energy production.