Soil nitrogen pools, forms, and losses in mature miscanthus x giganteus under nitrogen fertilization treatments

Miscanthus x giganteus is temperate climate dedicated energy crop with high biomass yield potential cultivated in the United States and Europe. Previous studies in young stands of Miscanthus x giganteus have shown little effect of nitrogen (N) fertilizer on yield production but have shown increased nitrate leaching and nitrous oxide (N2O) emissions. The effect of this crop on soil organic matter, mineralization of N, and available carbon has not been fully determined, especially after many years of production. This study monitored 10x10 m plots of Miscanthus x giganteus replicated four times across a range of soil types (Mollisols, Ultisols and Alfisols) in Illinois, Kentucky, Nebraska, and New Jersey that were established in 2008. Some of the sites were replanted in 2009 after a severe winter and Virginia was planted in 2010. Urea fertilizer was added annually (0, 60, and 120 kg N ha-1 yr-1) each spring. Above-ground biomass yields, nitrate and ammonium leaching, soil labile carbon (POX-C), soil potential mineralization of N (AnaN), and soil microbial activity (FDA) were evaluated during 2013 and 2014, building on previous work on these sites during the establishment phase. Biomass yields were generally large at all sites (15 to 20 Mg ha-1 yr-1) with greatest yields at Illinois and Nebraska (the two sites with Mollisols). Nitrogen fertilizer improved yields, however, it also greatly increased nitrate losses through leaching at all sites each year of the study. These losses were still increasing in the 6th and 7th years at 3 of the 5 sites and were higher with the 120 kg N ha-1 yr-1 treatment compared to the 0 or 60 kg N ha-1 yr-1. Potential soil mineralization of N and labile carbon were not affected by fertilization treatments in this study but sites with greater potential mineralization and labile carbon showed a greater microbial activity according to FDA results. However, it would be necessary to compare results of this analysis periodically to document changes in microbial community composition. Finally, there were few significant changes in soil total C and N at either depth, suggesting no major changes in soil organic matter after 6 years of production. Mature stands of Miscanthus x giganteus showed improvements in biomass production with the application of N fertilizer in this study but did not have an effect on POX-C or potential mineralization of N. In addition, a negative environmental impact of fertilization was shown as N losses through leaching which increased with fertilization rate.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Natural Resources and Environmental Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2017

Author dc:creator

• Molina, Miriam G

Contributors dc:contributor

• David, Mark B.
• Wander, Michelle M.
• Voigt, Thomas B.

• Miscanthus
• nitrogen
• fertilization
• leaching
• mineralization

Statement dc:rights

• Copyright 2016 Miriam Molina

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/95406

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/95406