Assessing corn stover composition and sources of variability via NIRS

Abstract

Corn stover, the above-ground, non-grain portion of the crop, is a large, currently available source of biomass that potentially could be collected as a biofuels feedstock. Biomass conversion process economics are directly affected by the overall biochemical conversion yield, which is assumed to be proportional to the carbohydrate content of the feedstock materials used in the process. Variability in the feedstock carbohydrate levels affects the maximum theoretical biofuels yield and may influence the optimum pretreatment or saccharification conditions. The aim of this study is to assess the extent to which commercial hybrid corn stover composition varies and begin to partition the variation among genetic, environmental, or annual influences. A rapid compositional analysis method using near-infrared spectroscopy/ partial least squares multivariate modeling (NIR/PLS) was used to evaluate compositional variation among 508 commercial hybrid corn stover samples collected from 47 sites in eight Corn Belt states after the 2001, 2002, and 2003 harvests. The major components of the corn stover, reported as average (standard deviation) % dry weight, whole biomass basis, were glucan 31.9 (2.0), xylan 18.9 (1.3), solubles composite 17.9 (4.1), and lignin (corrected for protein) 13.3 (1.1). We observed wide variability in the major corn stover components. Much of the variation observed in the structural components (on a whole biomass basis) is due to the large variation found in the soluble components. Analysis of variance (ANOVA) showed that the harvest year had the strongest effect on corn stover compositional variation, followed by location and then variety. The NIR/PLS rapid analysis method used here is well suited to testing large numbers of samples, as tested in this study, and will support feedstock improvement and biofuels process research.

Distribution of Structural Carbohydrates in Corn Plants Across the Southeastern USA

“…Conversely, as precipitation increased in AL, lignin content increased in the Pioneer hybrid. These variations could be attributed to genetic differences between corn hybrids [2] and/or differences in environmental conditions [16]. These results suggest that the differences in biomass composition can affect the amount of biofuel produced due to seasonal and regional climate variations.…”

“…A 2009 study [15] suggested that stover from above the ear had a higher quality for fermentation and that the lower portion (below the ear) was wetter and likely to have soil contamination (i.e., increased ash content). This vertical heterogeneity may also be influenced by genetic differences [2] and yearly environmental variations [16].…”

High throughput determination of glucan and xylan fractions in lignocelluloses

“…Past attempts to address the time-consuming nature of compositional analyses have considered spectroscopic methods, such as near-infrared (NIR), Molecular Beam Mass Spectroscopy (MBMS), and NMR with some success (Hames et al 2002(Hames et al , 2003Hames 2009;Templeton et al 2009;Labbe et al 2005;Ye et al 2008;Kelley et al 2004). The limited nature of these methods, however, requires extensive analysis of samples using more traditional (standard) methods in order to build models for determining compositional information from the various spectra.…”

From Tiny Microalgae to Huge Biorefi neries

“…Ground aboveground switchgrass samples were scanned using a nearinfrared spectrometer to predict cell wall and soluble carbohydrate biomass composition [30]. Ground corn stover samples were analyzed using a near-infrared spectrometer-based calibration equation developed by the National Renewable Energy Laboratory to predict corn stover cell wall composition [31]. Switchgrass and corn stover cell wall conversion to ethanol was based on composition components of glucan, xylose and arabinose [30,31].…”

“…Ground corn stover samples were analyzed using a near-infrared spectrometer-based calibration equation developed by the National Renewable Energy Laboratory to predict corn stover cell wall composition [31]. Switchgrass and corn stover cell wall conversion to ethanol was based on composition components of glucan, xylose and arabinose [30,31]. Glucan to ethanol conversion was assumed to be 85.5%, and xylose and arabinose was estimated to have 85% ethanol recovery efficiency [29].…”