Harvest and nitrogen effects on bioenergy feedstock quality of grass-legume mixtures on Conservation Reserve Program grasslands

Cheng Hsien Lin, Nictor Namoi, Amber Hoover, Rachel Emerson, Marnie Cortez, Ed Wolfrum, Courtney Payne, Josh Egenolf, Keith Harmoney, Robert Kallenbach, Do Kyoung Lee

Research output: Contribution to journalArticlepeer-review

Abstract

Perennial grass mixtures established on Conservation Reserve Program (CRP) lands can be an important source of feedstock for bioenergy production. This study aimed to evaluate management practices for optimizing the quality of bioenergy feedstock and stand persistence of grass-legume mixtures under diverse environments. A 5-year field study (2008–2012) was conducted to assess the effects of two harvest timings (at anthesis vs after complete senescence) and three nitrogen (N) rates (0, 56, 112 kg N ha−1) on biomass chemical compositions (i.e., cell wall components, ash, volatiles, total carbon, and N contents) and the feedstock energy potential, examined by the theoretical ethanol yield (TEY) and the total TEY (i.e., the product of biomass yield and TEY, L ha−1), of cool-season mixtures in Georgia and Missouri and a warm-season mixture in Kansas. The canonical correlation analysis (CCA) was used to investigate the effect of vegetative species transitions on feedstock quality. Although environmental variations (mainly precipitation) greatly influenced the management effect on chemical compositions, the delayed harvest after senescence generally improved feedstock quality. In particular, the overall cell wall concentrations and TEY of the warm-season mixtures increased by approximately 7%. Additional N supplies improved the total TEY of both mixtures by ~1.6–4.2 L ha−1 per 1.0 kg N ha−1 input but likely lowered the feedstock quality, particularly for the cool-season mixture. The cell wall concentrations of cool-season mixture reduced by approximately 3%–6%. The CCA results indicated that the increased legume compositions (under low N input) likely enhanced lignin but reduced ash concentrations. This field research demonstrated that with proper management, grass-legume mixtures on CRP lands can provide high-quality feedstock for bioenergy productions.

Original languageEnglish (US)
Pages (from-to)283-302
Number of pages20
JournalGCB Bioenergy
Volume15
Issue number3
DOIs
StatePublished - Mar 2023

Keywords

  • bioenergy feedstock quality
  • canonical correlation analysis
  • conservation reserve program
  • cool-season mixtures
  • harvest management
  • nitrogen management
  • warm-season mixtures

ASJC Scopus subject areas

  • Forestry
  • Renewable Energy, Sustainability and the Environment
  • Agronomy and Crop Science
  • Waste Management and Disposal

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