Herbaceous perennials represent a considerable portion of potential biomass feedstocks available for the growing bioenergy industry. Their chemical composition and biomass yields, which are important in determining ethanol potential on an area and mass basis, vary with plant variety and type, environment, and management practices. Therefore, a study was conducted to assess the variability of lignin and carbohydrate content, biomass yields, and theoretical ethanol yields on an area basis among different herbaceous perennial species combinations grown in Minot (2008) and Williston (2008, 2009, and 2010), North Dakota (ND). After wet chemistry compositional analysis was done, the carbohydrate contents were used to determine theoretical ethanol potential on a mass basis. Using the dry-matter yield, the theoretical ethanol yield on an area basis was also calculated for these biomass species. Total carbohydrate content for the biomass samples in Williston and Minot varied from 45 to 61% dry basis. Analysis of Variance (ANOVA) at a= 0.05 showed that carbohydrate content varied between years and environments. Also an interaction plot shows that no biomass species had consistently higher or lower carbohydrate content in the different environments. Switchgrass (Panicum vigatum L.) grown as single species or together with other perennial grasses had higher dry-matter yield and theoretical ethanol yield potential in Williston irrigated plots while mixtures containing intermediate or tall wheatgrass species (Thinopyrum spp.) produced better yields in Minot non-irrigated plots. Variability in theoretical ethanol yield on a mass basis (3.7% coefficient of variation (CV) in Williston and 9.7% CV in Minot) was much less than the variability in dry-matter yields (27.5% CV in Williston and 14.8% CV Minot). Therefore, biomass production is much more important than composition in choosing species to grow for ethanol production. Recently, many studies have focused on developing faster methods to determine biomass composition using near infrared (NIR) spectroscopy. Other NIR models have been developed on single biomass feedstocks but a broad-based model for mixed herbaceous perennials is yet to be developed. Therefore, NIR calibration models for lignin, glucan, and xylan were developed with 65 mixed herbaceous perennial species using a DA 7200 NIR spectrometer (950 - 1,650 nm) and GRAMS statistical software. The models for lignin and xylan had R(2) values of 0.844 and 0.872, respectively, upon validation and are classified as good for quality assurance purposes while glucan model had an R(2) of 0.81 which is considered sufficient for screening. The R(2) and the root mean square error of prediction (RMSEP) results showed that it is possible to develop calibration models to predict chemical composition for mixed perennial biomass when compared with results for models developed for single feedstock by Wolfrum and Sluiter (2009) and Liu et al. (2010). Studying the variability in predicting constituents using NIR spectroscopy over time (hours and days), it was observed that the average CV was between 1.4 to 1.6%. The average CV due to repacking (presentation) alone was 1.3%. The CVs for NIR predictions ranged between 1.4 to 5.7% while for wet chemistry ranged between 3.8 to 13.5%; hence, NIR predictions were more precise than wet chemistry analysis.

Aphthona spp. flea beetles were released in the Little Missouri National Grasslands (LMNG) in western North Dakota in 1999 to control leafy spurge (Euphorbia esula L.). The changes in soil seed bank composition and leafy spurge density were evaluated on two ecological sites five (2004) and ten years (2009) after Aphthona spp. release to monitor the effectiveness of the insects on weed control and associated change in plant communities. In 2009, leafy spurge stem density averaged 2 and 9 stems m-2 in the loamy overflow and loamy sites, respectively, compared to 110 and 78 stems m-2, respectively, in 1999 and 7 and 10 stems m-2, respectively, in 2004. Leafy spurge constituted nearly 67% of the loamy overflow seed bank in 1999 compared to 17% in 2004 and 2% in 2009. In the loamy seedbank, the weed represented nearly 70% in 1999 compared to approximately 11% in 2004 and 15% in 2009. As leafy spurge was reduced, native species diversity and seed count increased ten years following Aphthona spp. release. High-seral species represented 17% of the loamy overflow seedbank in 2009, an increase from 5% in 1999. However, Kentucky bluegrass, a non-target weedy species, increased over 250% in the loamy overflow seedbank from 2004 to 2009. The reestablishment of native plant species has often been slow in areas where leafy spurge was controlled using Aphthona spp. A bioassay was completed to evaluate native grass establishment when grown in soil from Aphthona spp. release and non-release sites throughout North Dakota. Native grass production was not affected when grown in soil collected from established Aphthona spp. sites (1.5 g per pot) compared to soil without insects (1.6 g per pot). The cause of reduced native grass production in sites with Aphthono spp. previously observed is unknown but may have been due to a chemical inhibition caused by the insects within the soil that no longer exists. The native warm-season switchgrass (Ponicum virgotum L.) may be an alternative to corn for efficient biofuel production; however, control of cool-season grassy weeds has been a problem in switchgrass production. Various herbicides were evaluated for smooth bromegrass (Bromus inermis Leyss.) and quackgrass [Elymus repens (L.) Gould] control in an established switchgrass stand near Streeter, ND and a weed-infested field in Fargo, ND. Switchgrass yield was higher than the control 14 mo after treatment (MAT) when aminocyclopyrachlor or sulfometuron were applied early in the growing season, but no treatment provided satisfactory long-term grassy weed control. Herbicides were reevaluated at increased rates for smooth bromegrass or quackgrass control in Fargo. Sulfometuron provided 99% smooth bromegrass control when applied at 280 g ha-1 in the fall but injured other grass and forb species as well. Sulfometuron would likely be injurious to switchgrass and could not be used for biofuel production. Aminocyclopyrachlor did not injure other grass species but only reduced smooth bromegrass control by 76% when applied at 280 g ha-1 in the fall. No treatment provided satisfactory long-term quackgrass control.

A mixed integer programming model is developed to determine a logistical design for maximizing rates of return to harvest, storage, transportation, and bioreflning of herbaceous crop residue for production of biofuels and feed for ruminant animals. The primary objective of this research is to identify the optimal location, scale, and number of pretreatment and biorefinery plants in northeastern North Dakota. The pretreatment and biorefinery plants are modeled under the assumption that they utilize recent technological advancement in AFEX and Simultaneous Saccharification and Fermentation, respectively. Potential feedstocks include wheat straw, barley straw, Durum straw, and com stover. Results indicate that the minimum ethanol rack price that will effectively trigger the production of cellulosic ethanol is $1.75 per gallon.