A biogeochemical analysis of Miscanthus x giganteus under nitrogen fertilizer treatments and across multiple soil types

Davis, Morgan

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https://hdl.handle.net/2142/46575 Copy

Description

Title

A biogeochemical analysis of Miscanthus x giganteus under nitrogen fertilizer treatments and across multiple soil types

Author(s)

Davis, Morgan

Issue Date

2014-01-16T17:54:39Z

Director of Research (if dissertation) or Advisor (if thesis)

David, Mark B.

Department of Study

Natural Res & Env Sci

Discipline

Natural Res & Env Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Miscanthus x giganteus
• Bioenergy
• Biogeochemistry
• soil organic matter greenhouse gas emissions
• inorganic nitrogen leaching

Abstract

The U.S. Department of Energy has mandated the production 16 billion gallons of renewable biofuel from cellulosic feedstocks by 2022. To reach production goals, large areas of land in the eastern U.S. will need to be dedicated to cellulosic feedstocks. Miscanthus x giganteus (M. x giganteus) is a perennial grass that is a potential candidate for cellulosic biofuel production because it has been shown to be highly productive with minimal inputs. Nitrogen (N) fertilization is being studied to see if M. x giganteus productivity is increased as well as potential environmental impacts. It is important to understand the effects of N fertilizer on M. x giganteus across a range of soil types and climatic factors. The objective of this study was to determine the effect of three different fertilizer treatments (0, 60, and 120 kg N ha-1 yr-1 annually as urea in spring) on biomass production, soil organic matter (SOM), and inorganic N leaching at five sites in the eastern U.S., and nitrous oxide (N2O) and carbon dioxide (CO2) emissions at one site (Illinois). Miscanthus x giganteus was planted during the spring of 2008 at Urbana Illinois, Lexington Kentucky, Mead Nebraska, and Adelphia New Jersey in 10 x 10 m plots, each replicated four times. The Gretna Virginia site was established a year later in 2010 replicating the same plot layout as the other sites. Site locations covered three different soil orders including two Mollisols (Illinois and Nebraska), two Ultisols (New Jersey and Virginia), and one Alfisol (Kentucky). There were no observed yield responses to fertilizer treatments, except at the Illinois site in 2012. In 2012 the 60 and 120 kg N ha-1 yr-1 treatments were significantly greater than the 0 kg N ha-1 yr-1 plots, which was likely due to extreme weather conditions. A late frost killed back emerged M. x giganteus, which was followed by extreme drought conditions during the summer months. The fertilized treatments likely benefited from supplemental N during the second emergence, but yield was reduced in all treatments from the previous year. Changes in labile SOM were determined by measuring potentially mineralizable N and permanganate oxidizable carbon (POX-C) in soil samples collected in 2008 and 2012. Potentially mineralizable N was found to increase across all fertilizer treatments and sites in the 0 – 10 cm soil depth, but not at 10 – 30 cm. Permanganate oxidizable carbon was driven by site history. An increase in POX-C in the 0 – 10 cm soil depth was found at both the Illinois and New Jersey sites; these sites were regularly tilled during the years preceding M. x giganteus planting. Decreases in POX-C were observed at the Kentucky and Nebraska sites in the 0 – 10 cm soil depth. These sites were both highly managed in turf grass production prior to M. x giganteus planting. Inorganic N leaching (at 50 cm soil depth using resin lysimeters) was measured at the Illinois site beginning in 2009, and at all sites in 2012. The fertilized plots had significantly greater nitrate leaching compared to the unfertilized plots every year after 2009 in Illinois and across all sites in 2012. The 120 kg N ha-1 plots had the greatest amount of nitrate leaching every year and across all sites during the study period (ranging from 10 to 39 kg N ha-1 yr-1). The 0 kg N ha-1 plots all stayed under 10 kg N ha-1 yr-1. The unfertilized plots had decreasing nitrate leaching as M. x giganteus established at the Illinois site. Nitrous oxide emissions measured from 2009-2013 at the Illinois site and were greater on fertilized plots. The 60 and 120 kg N ha-1 plots ranged in annual N2O emissions from 0.5 to 4.3 kg N ha-1 yr-1, and the 0 kg N ha-1 plots ranged from 0.1 to 0.5 kg N ha-1 yr-1. Carbon dioxide emissions were not found to be affected by fertilizer treatments. Miscanthus x giganteus altered SOM composition in only four years of production by increasing the amount of potentially mineralizable N at every site, regardless of N fertilization. However, N fertilization was found to increase both nitrate leaching at 50 cm soil depth and N2O emissions without increasing biomass production. This analysis demonstrates the negative environmental effects from N fertilized M. x giganteus across five soil types, and highlights the importance of future work on M. x giganteus N cycling, particularly in understanding why potential soil N mineralization rates were increased.

Graduation Semester

2013-12

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http://hdl.handle.net/2142/46575

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Copyright 2013 Morgan Davis

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