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In humid tropical environments, where soils are characteristically acidic and low in organic matter, lime and organic residues have been used to improve soil quality. A systematic consideration of their interaction is, therefore, crucial for land-based ecosystem management. A 28-day incubation pot study was carried out to investigate the main and interactive effects of lime and organic residue type (corn stover and vermicompost) on aggregate stability under rapid wetting (WSAr), saturated hydraulic conductivity (Ksat), and soil water repellency (SWR) on three acidic soils with contrasting clay content from Trinidad: Cunupia (Aquic Hapludalfs), Sangre Grande (Fluvaquentic Endoaquepts), and Talparo (Aquertic Eutrudepts). Organic residue had a significant (P ≤ 0.001) increasing effect on WSAr and Ksat for all three soils, this being highest for corn stover and lowest for no residue. Lime and organic residue interactive effects were only significant (P ≤ 0.05) for WSAr in the Cunupia soil, where lime significantly reduced WSAr in the vermicompost and no residue, but not in the corn stover treatment. Soil water repellency increased with clay content and was highest in the lime–corn stover treatment of the Talparo soil. Overall, our results suggest that applying crop residue with lime may help minimise the short-term deleterious effects of lime on the structural and hydraulic properties of humid tropical soils. Nonetheless, future experiments with a wider range of soils and organic residues need to be carried out for a longer term to validate our results.

Chemical pretreatment of lignocellulosic biomass is a critical step in the conversion of lignocellulose to biofuels and biochemical. The main drawback of this pretreatment process is the formation of inhibitors which exhibit combined toxicity to microorganisms and result to low product concentrations and yields. In this study, the selection of microbial consortia by enrichment on hydrolysate of H2SO4-pretreated corn stover (pre-CS) without detoxification has been investigated as an efficient way to develop new strategies for lignocellulose utilization. The analysis of cattle stomach-dervied microbial consortia domesticated to degrade hydrolysate of pre-CS to produce lactic acid (LA) at different temperatures was investigated. Bacterial 16S rRNA gene amplicon sequencing analyses indicated that the three microbial consortia were taxonomically distinct and Enterococcus became dominant at high temperature. The highest glucose consumption rate was observed at 45 °C, while the three microbial consortia showed similar consumption rates of xylose and arabinose. The selected microbial consortia DUT37, DUT45 and DUT47 showed preferable resistances to inhibitors in hydrolysate of pre-CS and abilities of xylose utilization. A batch simultaneous saccharification and fermentation (SSF) process was developed by microbial consortium DUT47 at 47 °C to produce LA from pre-CS under non-detoxified and non-sterile conditions. The LA concentration and yield were 43.73 g/L and 0.50 g/g-corn stover (CS), respectively. Microbial consortium DUT47 has been shown to be suitable for LA production from H2SO4-pretreated corn stover without detoxification due to its thermophilic growth characteristics, robust tolerance of inhibitors, and the simultaneous utilization of glucose and xylose.

Background Hardsetting soils are considered problem soils due to its behavior of becoming hard and unbearable to cultivate not until rewetted. Few investigations were conducted in this kind of problem soil; hence, information about biomass yield and nutrient uptake is still elusive. This study investigated the impact of potentially hardsetting soil on the biomass yield and nutrient uptake of sweet corn under no-tillage cultivation system with varying fertilization treatments. Results The application of full NPK + 1 Mg ha−1 VC increased stover and grain yield by 26–106% and 11–135%, respectively. Approximately 64% and 112% of sweet corn stover and grain yield increased when treated with full NPK. Highly significant quadratic relationship (P P Conclusion Application of organic amendment in combination with inorganic fertilizer could be a sustainable production strategy on sweet corn production system in potentially hardsetting soil under no tillage through enhanced nutrient uptake and biomass accumulation.

Prolonged lag phase and reactor instability make methane yield description and prediction challenging in upset solid-state anaerobic digestion (SSAD). Seven kinetic models (first-order (FOM), modified first-order (MFOM), Fitzhugh (FzM), logistic (LM), modified logistic (MLM), Cone (CM), and modified Gompertz (MGM) were employed for treatment evaluation. The treatments were dairy manure blended with calcium pretreated stover (8% Ca CSDM) or sodium pretreated corn stover (4% Na CSDM) or 2% aqueous ammonia pretreated corn stover (2% NH4 CSDM), or 4% aqueous ammonia pretreated corn stover (4% NH4 CSDM). The LM, CM, MLM with MGM, and MGM best described methane yield for 4% Na CSDM, 2% NH4 CSDM, 4% NH4 CSDM, and 8% Ca CSDM, respectively. Optimal hydraulic retention time predicted for the least inhibited treatment, 8% Ca CSDM, was 60 days. Therefore, non-hydrolysis rate limiting models (LM, MLM, FzM, MGM, and CM) could simulate methane yield, design of reactor’s volume, and develop degradation rate models in full-scale SSAD.

HighlightsAromatic compounds generated 72.6% of the total odor activity values (OAVs) over time.Cold treatments had significantly lower total OAVs than hot treatments regardless of the age of the bedded pack.Abstract. Beef cattle producers are beginning to raise cattle in confinement facilities such as slatted-floor barns, hoop barns, and mono-slope facilities. Hoop and mono-slope facilities typically use bedding packs as part of their manure management system, with crop residues being the most commonly used bedding material. This study was conducted to determine the effects of bedding material, i.e., corn stover (CS), bean stover (BS), wheat straw (WS), or pine wood chips (PC), and environmental ambient temperature, i.e., cold (15°C) or hot (30°C), on the concentrations of odorous volatile organic compounds (VOCs) in air samples collected in the headspace above lab-scale bedded packs over a 42-day period. Total aromatic compounds, sulfide compounds, straight-chain fatty acids (SCFAs), and branched-chain fatty acids (BCFAs) were measured and used to calculate total odor activity values (OAVs) for each bedding and temperature effect. No significant three-way interactions for bedding material × ambient temperature × age of bedded pack were observed. Significant bedding material × ambient temperature interactions were observed for total aromatic compounds and total sulfide compounds (p = 0.0455 and p = 0.0083, respectively). The concentration of total aromatic compounds was greater for all hot treatments compared to cold treatments, with hot-CS and hot-WS bedding types (389.83 and 365.5 ng L-1, respectively) significantly (p < 0.05) greater than all other bedding types, while total aromatic compounds were lowest (87.09 ng L-1) for BS across cold treatments. Total sulfide compounds from cold-PC (51.69 ng L-1) were significantly (p = 0.0143) greater than all other treatments. Within hot treatments, total sulfide compounds were similar across all bedding materials. Total SCFAs for both cold and hot treatments decreased significantly from weeks 4 to 6. Total SCFA concentrations within weeks were significantly (p < 0.0001) greater for WS and CS compared to BS and PC but similar across bedding materials at week 6. Total BCFA concentrations from bedded packs containing CS and WS were significantly (p < 0.0001) higher at week 4 compared to concentrations from bedded packs containing BS or PC. As bedded packs aged, total BCFA concentrations for all bedding materials were similar at week 6. Total OAVs decreased over time for both hot and cold treatments, although cold treatments had significantly (p < 0.0001) lower total OAVs regardless of the age of the bedded pack. Aromatic compounds generated 72.6% of the total OAV over the 42-day study. Bedding types BS and PC had the lowest total OAVs across all weeks. The results indicate that feedlot operators maintaining bedded pack facilities will achieve the greatest overall odor reduction when using BS or PC bedding material, no matter the ambient temperature. Keywords: Bedding, Beef, Odor, Volatile organic compounds.

The moisture content of corn stover during the harvest season in the Huang-Huai-Hai region of China is approximately 50%. To achieve rapid off-field transportation and to prolong its shelf life, a method suitable for corn stover with medium-high moisture content was considered based on the stover multistage continuous cold roll forming method. An orthogonal experiment was adopted by taking the moisture content, sterilization method, and inhibitor addition method as experimental factors and taking the shelf life, percent rebound, and density of the molding blocks as the experimental indices. It was found that the steam sterilization method can prolong the shelf life of the molding block the most. The percent rebound and the density were primarily affected by the moisture content, followed by the sterilization method. A comprehensive analysis indicated that the optimal treatment mode was a moisture content of 45%, and the optimal sterilization method was steam sterilization with no inhibitor. In this mode, the molding block can be stored for 72 h without mildew with an average temperature of 32 °C and an average humidity of 48% during the day. The percent rebound was 24.3%, and the density can reach 310 kg/m3 after the completion of rebound.

Policy support for cellulosic biofuels is contingent on their achieving much greater reductions in life-cycle greenhouse gas emissions than corn starch ethanol. Biomass sorghum has been suggested as a genetically and agronomically tractable feedstock species to augment near-term cellulosic feedstock production. This study used DayCent modeling to investigate biomass sorghum production emissions relative to corn with and without stover utilization at 3,265 across the rainfed United States. Sorghum produced greater average feedstock dry matter (15.6 ± 1.4 vs 14.8 ± 2.2 Mg ha-1 yr-1) and slightly lower estimated ethanol energy yields (10.6 ± 1.0 vs 11.8 ± 2.9 MJ m-2 yr-1) as corn grain with 75% stover collection. The high biomass removals in both the sorghum and corn stover scenarios led to soil organic carbon losses on 90 and 100% of sites, respectively. Average feedstock production emissions intensities were similar between sorghum and corn with 75% stover removal (17.6 ± 2.8 vs 18.8 ± 3.0 g CO2e MJ-1), but were notably lower under sorghum for sites in the southwestern study region (13.6 ± 3.0 vs 22.5 ± 3.1 g CO2e MJ-1). These results suggest that biomass sorghum produces cellulosic feedstock with similar emissions to corn grain and at current yield levels is unlikely to meet the Renewable Fuel Standard emissions reduction threshold for cellulosic biofuels.

Objective: This study investigated a method of preparing corn stover for Irpex lacteus (I. lacteus) treatment to improve its in vitro rumen degradability under non-sterile conditions.Methods: Corn stover was inoculated with Lactobacillus plantarum (L. plantarum), Lactobacillus buchneri (L. buchneri), and an equal mixture of these strains, and ensiled for 0, 3, 7, 14, and 28 days. After each period, a portion of the silage was sampled to assess the silage quality, and another portion of the silage was further treated with I. lacteus at 28°C for 28 d. All the samples were analyzed for fermentation quality, chemical composition, and in vitro gas production (IVGP) as a measure of rumen fermentation capacity.Results: Lactic acid bacteria (LAB) was found to improve the silage quality of the corn stover, and the corn stover silage inoculated with L. plantarum produced more lactic acid and higher IVGP than other silage groups. The I. lacteus colonies flourished in the early stage of corn stover silage, especially on the 3-d corn stover silage inoculated with both L. plantarum and L. buchneri. This led to an 18% decrease in the acid detergent lignin content, and a 49.6% increase in IVGP compared with the raw stover.Conclusion: The combination of ensiling with the mixed LAB inoculation and I. lacteus treatment provided a cost-effective method for the improvement of the IVGP of corn stover from 164.8 mL/g organic matter (OM) to 246.6 mL/g OM.

Protective effects of five surfactants were investigated relative to the saccharification of lignocellulose using the impeded Michaelis-Menten model (IMM). The yield of total reducing sugar (Ytrs) and cellulase activity were indexed as the effect of surfactant. The IMM was used to fit the correlation between Ytrs and reaction time to obtain the index (Kobs,0) reflecting the accessibility between cellulose and lignocellulose and the comprehensive index (Ki) reflecting cellulase inactivation and non-specific site adsorption. Results showed that the strongest protective effect was found from polyoxyethylene (80) sorbitan monooleate, followed by rhamnolipid. The surfactants protected cellulase from inactivation and nonspecific site adsorption of lignocellulose in the saccharification, leading to enhanced cellulase activity, especially with respect to carboxymethyl cellulase (CMCase) and filter paper enzyme (FPase) activities. The maximum Ytrs was obtained when the CMCase activity was 136.2 U/mL, while the FPase and β-glucosidase activities should be as high and low as possible, respectively, under the optimized condition. These findings lay the foundation for improving the saccharification efficiency of cellulase and reducing the cost of saccharification of biomass cellulose.

Traditional approaches for corn stover utilization create an inhomogeneous, whole plant mixture that does not achieve performance and cost targets for biofuel production. The improvement of convers...

Fresh corn stover, which could be separated into fermentable juice and lignocellulosic bagasse, is considered as an alternative raw material for second-generation ethanol production. However, the influence of harvest time of corn stover on ethanol yield has not been evaluated yet. In this work, aiming to improve ethanol yield from fresh corn stover, the harvest time was redefined and optimized. Liquefaction plus simultaneous saccharification and co-fermentation (L + SScF) was carried out to define the realistic ethanol yields. Results showed that compared with the corn stover harvested in the end of physiological stage, the conventional harvest stage, the corn stover harvested in dent stage provided the highest theoretical ethanol yield of 9.92 t/ha (5.64 t/ha for the case that exclude xylan derives). 3.53 t/ha of ethanol was produced from the fresh stover harvested in dent stage, which was 1.64 times higher than using the stover obtained in the conventional harvest time. This study demonstrated that bio-ethanol yield was hugely influenced by harvest time of corn stover, and the stover harvested in dent stage has the highest ethanol yield.

HighlightsRotary knives were added to an ear-snapper header to increase corn stover yield in a single-pass biomass system.Stover yield increased with the number of knives but at the expense of combine productivity and fuel consumption.Bale moisture was often greater than would be considered appropriate for good aerobic conservation.Abstract.Modifications were made to a conventional ear-snapper corn header to increase corn stover yield when a single-pass round baling system was integrated with a combine harvester. To collect more leaves and top portions of stalks, knives oriented parallel to the deck plates were added to shear crop material above the ear-snapper rolls. Stover yield was primarily altered by the number of knives on the header; and to a lesser extent by the fore-and-aft position of the knives and the header height. The number of knives on a 12-row header was varied from two to six in increments of two. Stover yield increased linearly with the number of knives, and dry basis stover yield ranged from 1.1 Mg ha-1 (no knives) to 3.6 Mg ha-1 (six knives) over the five years of data collected (2012 to 2016). Combine productivity decreased linearly and specific fuel consumption increased linearly with greater stover yield. Combine productivity declined by as much as 50% when six knives were used. Dry basis bale density decreased linearly with the number of knives because the dense cobs became a smaller fraction of the total bale mass. In three of the five years, bale moisture increased linearly with the number of knives; in those three years, bale moisture was typically greater than 30% (wet basis). Adding knives to the header increased single-pass stover yield but at considerable cost to combine harvester productivity, and aerobic bale conservation would be challenged by high bale moisture. Keywords: Baling, Combine, Corn, Density, Moisture, Productivity, Stover, Yield.

Objective To effectively use corn stover resources as animal feed, we explored the chemical composition and in vitro digestibility of corn stover during field exposure and the fermentation characteristics of silage prepared with lactic acid bacteria (LAB) and cellulase. Methods Corn ears including the cobs and shucks were harvested at the ripe stage. The corn stover was exposed in the field under natural weather conditions. Silages were prepared after 0, 2, 4, 7, 15, 30, and 60 d of exposure. Corn stover was chopped into approximately 1 to 2 cm lengths and then packed into 5 liter plastic silos. The ensiling density was 550.1±20.0 g/L of fresh matter, and the silos were kept at room temperature (10°C to 25°C). Silage treatments were designed as follows: without additives (control), with LAB, with cellulase, and with LAB+ cellulase. After 45 d of fermentation, the silos were opened for chemical composition, fermentation quality and in vitro digestion analyses. Results After harvest, corn stover contained 78.19% moisture, 9.01% crude protein (CP) and 64.54% neutral detergent fiber (NDF) on a dry matter (DM) basis. During field exposure, the DM, NDF, and acid detergent fiber (ADF) contents of corn stover increased, whereas the CP and water-soluble carbohydrate contents and in vitro digestibility of the DM and CP decreased (p

Rapid treatment processing for corn stover and black liquor is of the utmost importance with the boom in China’s agriculture sector. Aerobic fermentation composting via microbial/black liquor inoculation is superior to traditional composting with enhanced compost maturity and accelerated organic matter degradation. This research aimed to investigate the feasibility of black liquor addition and the effect of microbial/black liquor inoculation on the chemical composition and physiochemical and biological parameters for compost quality assessment. Results indicated that both the microbial/black liquor and the black liquor inoculation improved the heating rate. After composting for 18 days, the C contents and H contents were decreased to 44.29 ± 0.19% and 5.98 ± 0.05%, while the O contents and N contents were increased to 45.25 ± 0.15% and 3.48 ± 0.01%, which is consistent with the results of elemental analysis. This result indicated that black liquor and microbial inoculations accelerated the formation of nitrogen structures and recalcitrant nitrogenous oxygenated compounds. The FTIR analysis of four treatments confirmed that the microbial/black liquor inoculation could promote lignocellulose degradation and lignin degradation in subsequent composting. 16S rRNA sequencing revealed Deinooccola, Gemmatimonadota, and Chloroflexi as the predominant bacteria. The study suggested corm stover/black liquor composting as a promising technique for rapid and enhanced quality compost production.

This study deals with the impact of calcination, alkalinity, and curing time parameters on the hydrothermal synthesis of zeolite A. The zeolite A sample, produced from corncob-stalk-and-leaves (corn stover) ash was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analysis (TGA), and scanning electron microscopy (SEM). The results showed that calcination, alkalinity, and curing time have significant effects on the crystallization and the morphology of zeolite A. In addition, these parameters also impacted the cation exchange capacity. Furthermore, the synthesized zeolite A was obtained using a calcination temperature of 500 °C within two hours of airflow, which is much lower than the temperatures previously reported in the literature for an agricultural waste and other waste materials. A fusion ratio of corn stover ash:NaOH of 1.0:1.5 and a curing time of nine hours were achieved. This is a major result as this curing time is much lower than those featured in other studies, which can reach up to twenty-four hours. In this paper, cubic crystal with rounded edge of zeolite A, having a cation exchange capacity of 2.439 meq Na+/g of synthesized anhydrous zeolite A, was obtained, which can be a good candidate for ion-exchange separation.

Xylose fermentation is an essential issue for lignocellulosic ethanol production, which is often inhibited by degradation products generated during biomass pretreatment. In this study, enzymatic hydrolysate of dilute acid pretreated corn stover was fermented using Zymomonas mobilis 8b. With the solid loading of corn stover increased from 5 to 24 wt.%, the xylose consumption volume decreased from 97.0 to 21.5%. The ethanol produced ranged from 7.8 to 28.6 g/L. In order to improve xylose consumption, corn slurry was integrated into the corn stover ethanol process. Integration strategies, glucoamylase dosage, and corn–corn stover mixing ratio were investigated. Results showed that introducing corn slurry into corn stover hydrolysate was an effective way to improve xylose fermentation as well as enhance ethanol titer. Specifically, when liquefied corn slurry was introduced into corn stover hydrolysate at the ratio of 1:1 and total solid loading of 24%, the xylose consumption volume exceeded 88% with the final ethanol titer reached 68.6 g/L. This study indicates that integration of the first- and the second-generation ethanol processes is beneficial to xylose fermentation.

The movement of solid material into and between unit operations within a biorefinery is a bottleneck in reaching design capacity, with formation of biomass slurries needed to introduce feedstock. Corn stover slurries have been achieved from dilute acid, pretreated materials resulting in slurry concentrations of up to about 150 g/L, above which flowability is compromised. We report a new strategy to liquefy corn stover at higher solids concentration (300 g/L) by initially cooking it with the enzyme mimetic maleic acid at 40 mM and 150 °C. This is followed by 6 h of enzymatic modification at 1 FPU (2.2 mg protein)/g solids, resulting in a yield stress of 171 Pa after 6 h and 58 Pa in 48 h compared to 6806 Pa for untreated stover. Mimetic treatment of corn stover pellets minimizes the inhibitory effect of xylo-oligomers on hydrolytic enzymes. This strategy allows for the delivery of solid lignocellulosic slurry into a pretreatment reactor by pumping, improving operability of a biorefinery.

Biochars are used for soil fertility improvement because they may contain certain elements that plants use as nutrients. However, few studies have demonstrated enhanced crop nutrient uptake. Our study examined nutrient uptake responses of corn (Zea Mays L.) grain and stover over 4 years (Y) after a Goldsboro sandy loam (fine-loamy, siliceous, sub-active, thermic Aquic Paleudults) received different designer biochars and a compost. The designer biochars were produced from lodgepole pine (Pinus contorta) chip (PC), poultry litter (PL), blends with switchgrass (SG, Panicum virgatum), and a SG compost alone. Topsoil treated with 100% PL biochar and blended PC:PL biochar had significantly greater Mehlich 1 (M1) extractable P, K and Na contents compared to the control or other treatments. No significant differences were detected in annual grain nutrient concentrations. In the first corn stover harvest (Y1), significantly greater concentrations of P and K were taken up after treatment with 100% PL biochar, with PC:PL blend and with SG when compared to control. By the fourth corn stover harvest (Y4), nutrient uptake between treatments was not significantly different. Biochar impact on corn stover P, K and Na concentrations was time dependent, suggesting that repeated biochar applications may be needed.

Despite decades of research, Integrated Biorefineries (IBRs) are still not commercially viable because of the long-standing, unresolved challenges related to biomass solids handling and transport (e.g., flowability and fouling), and pretreatment e.g., wettability and conversion). The compendium of challenges facing IBRs lead to operational reliability and time-on-stream estimates of 30%, yet economically viable IBRs require greater than 90% operational reliabilities. The performance of commercial solids handling operations is largely dependent on the fundamental thermodynamic property, surface energy. Combining surface area, thermogravimetric, and inverse gas chromatography analyses, we show the observed differences in surface energy (e.g., wettability and work of cohesion) for anatomically air fractionated corn (Zea mays L.) stover. This study highlights the importance of understanding and tuning biomass surface energy to improve IBR solids handling and transport, and pretreatment operations.

Twenty-eight bulls weighing 227 ± 6.8 (SD) kg were randomly assigned to four concentrate levels (1-1.5 kg [low level of concentrate {LC}], 1.5-2 kg [medium level of concentrate], 2-2.5 kg [high level of concentrate {HC}], and 2.5-3 kg [highest level of concentrate {H+C}]) and fed corn stover silage ad libitum. At the beginning of the experiment, the bulls in each treatment were fed 1, 1.5, 2, and 2.5 kg of concentrate, respectively, and these levels were increased by 0.25 kg at the end of each month to compensate for the growth requirements of the bulls. After three months, increases in the concentrate level from LC to HC resulted in increased (P

A novel pretreatment method combining freezing-thawing and ammonia was developed, and the system stability and anaerobic conversion performance of corn stover (CS) were investigated. The CS was pretreated by water freezing-thawing (water-FT) and ammonia freezing-thawing (ammonia-FT), and then pretreated and untreated CS were anaerobically digested in three continuously stirred tank biodigesters (CSTBRs) at three organic loading rate (OLR) of 1.6, 1.8 and 2.0 gVS L−1 d−1. The analyses showed that pH value and volatile fatty acids (VFAs) concentration of three systems were in reasonable ranges of 6.8–7.5 and 160–330 mg L−1, respectively. Total ammonia nitrogen (TAN) in R3 system ranged from 600 mg L−1 to 1300 mg L−1, which was conducive to maintain system stability. The removal amount of soluble chemical oxygen demand (SCOD) of CS by ammonia-FT pretreatment was 17.3–20.5% higher than that of water-FT pretreatment. The results also showed that CS pretreated by ammonia-FT achieved 27.8–32.4% and 13.9–16.1% more methane yield (250–267 mL gvs−1) than those of untreated and water-FT pretreatment, respectively. Correspondingly, ammonia-FT pretreated CS in R3 obtained the highest conversion rates of 47.7%, 56.9%, 42.7%, and 48.8% for TS, VS, cellulose, and hemicellulose, respectively, and the lowest cost was of 0.0336 USD m3 CH4−1 and the highest energy recovery of 2428.1 kWh kgvs−1. The study demonstrated that ammonia-FT pretreatment is one of efficient and cost effective method for stable CS bioconversion.

Measured field data were used to compare two allocation methods on life cycle greenhouse gas emissions from corn (Zea mays L.) stover production in the Midwest U.S. We used publicly-available crop yield, nitrogen fertilizer, and direct soil nitrous oxide emissions data from the USDA-ARS Resilient Economic Agricultural Practices research program. Field data were aggregated from 9 locations across 26 site-years for 3 stover harvest rates (no removal; moderate removal – 3.1 Mg ha−1; high removal – 7.2 Mg ha−1) and 2 tillage practices (conventional; reduced/no-till). Net carbon uptake by crops was computed from measured plant carbon content. Monte Carlo simulations sampled input distributions to assess variability in farm-to-gate GHG emissions. The base analysis assumed no change in soil organic carbon stocks. In all cases, net CO2 uptake during crop growth and soil-respired CO2 dominated system emissions. Emissions were most sensitive to co-product accounting method, with system expansion emissions ∼15% lower than mass allocation. Regardless of accounting method, lowest emissions occurred for a moderate removal rate under reduced/no-till management. The absence of correlations between N fertilization rate and stover removal rate or soil N2O emissions in this study challenges the use of such assumptions typically employed in life cycle assessments Storage of all carbon retained on the field as SOC could reduce emissions by an additional 15%. Our results highlight how variability in GHG emissions due to location and weather can overshadow the impact of farm management practices on field-to-farm gate emissions.

Fungal pretreatment with the white rot fungus Ceriporiopsis subvermispora was performed under non-sterile conditions for four different feedstocks, corn stover, miscanthus, softwood, and hardwood, using a sequential inoculation process that employed fungal-colonized feedstock as inoculum. Fungal pretreatment improved the enzymatic digestibility of unsterilized hardwood, softwood, and miscanthus after the first generation of the sequential process, increasing the glucose yield by 2-, 3- and 4.5- fold, and the xylose yield by 9-, 7- and 10- fold, respectively. However, the fungal pretreatment of unsterilized feedstocks was unsuccessful for corn stover throughout the sequential process and for all feedstocks for the second and third generation. Modifications in feedstock structure and composition were analyzed using microscopy, spectroscopy, and thermogravimetric analysis, and showed that the effects of fungal pretreatment with C. subvermispora were feedstock-dependent. A significant fungal colonization was observed in all the fungal pretreated feedstocks, but an extensive cell wall degradation was only detected in miscanthus and hardwood. Lignin-to-cellulose ratio decreased in all successful fungal pretreated feedstocks, but the lignin units (syringyl, guaiacyl, or p-hydroxyphenyl units) that were preferentially degraded varied with each feedstock. Interestingly, C. subvermispora was able to degrade terpenes from the pine resin during the fungal pretreatment of pine wood (softwood).

Three experiments were conducted to determine the effectiveness of calcium hydroxide (Ca(OH)2) addition and roughage inclusion on digestibility, performance, and carcass characteristics of steers fed 60% dried distillers grains with solubles (DGS). Statistical analyses for studies were conducted using the MIXED procedures of SAS. In experiment 1, 48 steers (353.5 ± 7.55 kg) were allotted to individual pens and fed 1 of 3 diets (dry matter [DM] basis) containing 60% dried DGS, 20% corn silage, and 4% supplement with: 1) 14.5% corn and no Ca(OH)2; 2) 14% corn and 2% Ca(OH)2; and 3) 14.5% additional corn silage and no Ca(OH)2. Steers fed Ca(OH)2 consumed the least (P = 0.03) and steers fed added corn silage consumed the most and had the least gain:feed (P = 0.02). Gain and carcass quality were not affected by treatment (P ≥ 0.48). In experiment 2, 112 steers (375.3 ± 19.25 kg) were allotted to pens (four pens per treatment; seven steers per pen) arranged as a 2 × 2 factorial (roughage × Ca(OH)2) and fed one of four diets (DM basis) containing 60% dried DGS, 17% corn silage, and 4% supplement with: 1) 17.5% corn silage and no Ca(OH)2; 2) 17% corn silage and 2% Ca(OH)2; 3) 17.25% corn stover and no Ca(OH)2; and 4) 17% corn stover and 2% Ca(OH)2. Added stover decreased average daily gain (ADG) compared to added corn silage (P = 0.04). Ca(OH)2 increased ADG when steers were fed stover, but not when steers were fed only corn silage (P = 0.05; interaction). In experiment 3, six ruminally cannulated steers (initial body weight = 352 ± 14.8 kg) were randomly allotted to a 6 × 6 Latin square design to determine the effects of roughage inclusion (corn, corn silage, stover) and Ca(OH)2 addition (0% or 2%) on ruminal characteristics. Feeding stover decreased total volatile fatty acid(s) (VFA) concentration and DM digestibility compared to corn silage or corn (P < 0.01), whereas Ca(OH)2 resulted in greater total VFA concentrations and DM digestibility (P ≤ 0.02). Stover increased rate of DM degradation (Kd) and rate of particle outflow from the rumen (P ≤ 0.04) but decreased extent of DM digestion and mean retention time (P ≤ 0.02) compared to corn or silage. Ca(OH)2 increased Kd (P < 0.01) and tended to increase (P = 0.06) liquid passage rate. In conclusion, added roughage did not improve performance of cattle fed 60% dried DGS. Ca(OH)2 may decrease intake and maintain performance of cattle fed 60% dried DGS with corn silage as the roughage source and increases ADG when corn stover replaces a portion of the corn silage.

Solar pyrolysis of agricultural waste has huge potential for sustainable production of fuel and chemical feedstock. In this paper, the kinetics, thermodynamics, and physical characterization of corn stover (CS) collected from Wyoming, USA was conducted with respect to solar pyrolysis. The kinetics and thermodynamics of the CS pyrolysis was analyzed in detail using the methods described by KAS (Kissinger-Akahira-Sunose) and FWO (Flynn-Wall-Ozawa), from which the activation energy, Gibbs energy, Arrhenius pre-exponential factor, enthalpy, and entropy were derived.14 other kinetics models based on reaction order, diffusion, nucleation, geometric contraction, power models were also examined, and models based on diffusion was found to be best suited. The CS was used for solar pyrolysis of biomass and the products were analyzed by mass spectroscopy, ICP-MS, GPC, micro-GC, and Elemental analyzer. The results show that CS is suitable for solar pyrolysis to produce chemicals and other fuels.

Ceriporiopsis subvermispora was used to modify corn stover for improving the biodegradability and biomethane yield. Corn stover was incubated with C. subvermispora for 5–90 days then anaerobically digested. It was found that the corn stover modified for 15 days achieved the highest biomethane yield of 235 mL·g−1 VS, which was an increase of 15.2% over that of the non-modified one. The mechanism analyses indicated that the improvement resulted from the combined roles of degradation selectivity, destruction of lignocellulosic structures, and linkages. The analyses showed that C. subvermispora has a high relative selectivity of lignin degradation. The structure of the lignin and the linkages among lignin and hemicellulose and cellulose were broken obviously by acetyl group removal, and the enzymatic hydrolysis of cellulose was increased by 35.61%. The finding indicated that C. subvermispora modification is one of the effective methods for enhancing biomethane yield of corn stover.

Corn stover removal for biofuels production removes potentially recyclable nutrients and carbon challenging the sustainability of the process. Therefore, this study focused on quantifying the distributions of dry matter, nitrogen, phosphorus, potassium, carbon, sugars and lignin in corn stover fractions, and cobs. In 2016 and 2017, corn plants from different hybrids were collected from a corn field in Ohio at two maturity levels. The properties were evaluated for different non-grain corn plant fractions (i.e., stover fractions above and below ear, and cob). Stover fractions below and above ear (not including cobs) and cobs contributed, respectively, to 42–56%, 31–38%, and 13–18% of the total non-grain aboveground dry matter in 2 years. Glucose and lignin concentrations were uniformly distributed and ranged from 321 to 407 mg/g and 87 to 158 mg/g, respectively, for both years. Cobs contained the highest concentration of other sugars (351–361 mg/g) in both years, compared to 217–298 mg/g in other fractions. Nitrogen and phosphorus were uniformly distributed across the different corn stover and cob fractions, ranging between 4–20 mg/g and 0.2–1.5 mg/g, respectively. Potassium concentration was the highest in stover fraction below ear (10–24 mg/g) compared to 5–11 mg/g in other fractions. The results suggest that harvesting cob and above ear stover fractions from the field would allow corn stover collection with suitable sugar concentrations for biofuels/products while retaining stover fractions with higher nutrients concentrations in the field.

Background Efficient and economically viable production of biofuels from lignocellulosic biomass is dependent on mechanical and chemical pretreatment and enzymatic hydrolysis of plant material. These processing steps yield simple sugars as well as plant-derived and process-added organic acids, sugar-derived dehydration products, aldehydes, phenolics and other compounds that inhibit the growth of many microorganisms. Lipomyces starkeyi is an oleaginous yeast capable of robust growth on a variety of sugars and lipid accumulation on pretreated lignocellulosic substrates making it attractive as an industrial producer of biofuels. Here, we examined gene expression during batch growth and lipid accumulation in a 20-L bioreactor with either a blend of pure glucose and xylose or pretreated corn stover (PCS) that had been enzymatically hydrolyzed as the carbon sources. Results We monitored sugar and ammonium utilization as well as biomass accumulation and found that growth of L. starkeyi is inhibited with PCS hydrolysate as the carbon source. Both acetic acid and furfural are present at concentrations toxic to L. starkeyi in PCS hydrolysate. We quantified gene expression at seven time-points for each carbon source during batch growth and found that gene expression is similar at physiologically equivalent points. Analysis of promoter regions revealed that gene expression during the transition to lipid accumulation is regulated by carbon and nitrogen catabolite repression, regardless of carbon source and is associated with decreased expression of the translation machinery and suppression of the cell cycle. We identified 73 differentially expressed genes during growth phase in the bioreactor that may be involved in detoxification of corn stover hydrolysate. Conclusions Growth of L. starkeyi is inhibited by compounds present in PCS hydrolysate. Here, we monitored key metabolites to establish physiologically equivalent comparisons during a batch bioreactor run comparing PCS hydrolysate and purified sugars. L. starkeyi’s response to PCS hydrolysate is primarily at the beginning of the run during growth phase when inhibitory compounds are presumably at their highest concentration and inducing the general detoxification response by L. starkeyi. Differentially expressed genes identified herein during growth phase will aid in the improvement of industrial strains capable of robust growth on substrates containing various growth inhibitory compounds. Electronic supplementary material The online version of this article (10.1186/s13068-019-1510-z) contains supplementary material, which is available to authorized users.

Corn stover and sugarcane bagasse are the most widely available agriculture processing biomass and could serve as feedstocks for production of biofuel. In this study, three different technologies are combined to develop a more efficient conversion process for each of these feedstocks. The three technologies are diluted alkaline deacetylation process, combined thermochemical and mechanical shear pretreatment, and fermentation using a combined inoculum of two commercial Saccharomyces yeast strains. The two yeast strains used were a non-GMO and GMO strain engineered for xylose fermentation. The final ethanol concentrations obtained were 35.7 g/L from deacetylated corn stover and 32.9 g/L from sugarcane bagasse. Blending the two yeast reduced residual xylose content from 1.24 g/L to 0.48 g/L and increased ethanol production by 6.5% compared to solely using the C5/C6 yeast. The optimized yeast blend also lowered the amount of C5/C6 yeast required for inoculation by 80%.

We demonstrate the use of a surrogate-based optimization framework for large-scale and high-resolution landscape management optimization, using irrigated corn production systems in eastern Colorado, USA as a case study. An artificial neural network was employed to create a surrogate of the DayCent biogeochemical simulation model. Our optimization considered trade-offs among seven different objectives at different scales, including farm profits, irrigation water use, corn grain, corn stover, soil organic carbon (SOC), greenhouse gas (GHG) emissions, and nitrogen leaching. The results show that the surrogate captured greater than 99% of the variations in the DayCent’s simulated outputs and was 6.2 million times faster than the DayCent model for our analysis. Farm-level optimization increased farm profits by 83%–150%, SOC by 16%–53%, grain yield by 10.1–11.3%, and reduced GHG emissions by 19%–55% compared to the ‘business-as-usual’ scenario.

This document studies the hydration dynamics of five lignocellulosic biomasses (sorghum and wheat straws, corn stover, agave and sugarcane bagasses) commonly used as feedstock in biorefining processes. Water holding and water retention capacities are measured for different particle sizes of each lignocellulosic biomass at different hydration times under isothermal conditions. Water holding capacity exhibits a first-order dynamic behaviour fitting a Langmuir isotherm as a function of hydration time. The two isotherm constants are interpreted as the maximum water holding value of the lignocellulosic biomass (α) and the time typically required to reach it (β), fitting experimental data with high correlation factors (0.981–0.998). Equilibrium hydration values differ greatly for each biomass and particle size, demonstrating that holding and retention capacities are associated to biomass type and surface size. The relationship between hydration with pH decay and glucose release due to microbial and fungal activity during hydration dynamics was also evaluated.

Multiple generations of biofuel manufacturing technologies have been proposed and developed, among which first generation technology is the most mature. It typically utilizes corn grain as feedstock in bio-refineries in many countries such as the United States. However, the use of edible matter of crops like corn may lead to a food-versus-fuel competition. To address such an issue, second generation biofuel manufacturing technology using the non-edible matter of crops has been developed. In this paper, the economic viability and environmental sustainability are analyzed and quantified, when restructuring the biofuel supply chain from employing first generation manufacturing technology to the one utilizing second generation technology considering the existing supply chain infrastructure. Two supply chain restructuring strategies, i.e., distributed and centralized preprocessing deployment, are modeled for implementing biomass preprocessing for second generation biofuel manufacturing. Bi-objective optimization formulations for the corn stover-sourced biofuel (a typical second generation biofuel) supply chain considering both economic and environmental aspects are proposed under both strategies. Different decision variables such as the locations selected for constructing preprocessing centers and the corresponding corn stover handling capacities of such centers, as well as the material flows between farms, preprocessing centers, and bio-refinery plants are identified. A case study based on the state of Missouri in the United States is implemented to illustrate the effectiveness of the proposed model and analyze the performance of different strategies. The results of the case study show that when corn stover is used as feedstock in bio-refineries, the unit cost of bioethanol production can be reduced, while the unit emission is increased compared to the corn-sourced supply chain under both supply chain restructuring strategies. Specifically, in Missouri where the daily stover handling amount per bio-refinery plant is relatively low and the stover collection radius is relatively small, the centralized strategy outperforms the distributed one with a higher cost reduction and a smaller increase in emissions. It reduces the unit cost by 27.39%, while increasing the unit emission by 24.42%, compared to the corn-sourced supply chain.

Harvesting corn stover removes N from the fields, but its effect on subsurface drainage and other N losses is uncertain. We used the Root Zone Water Quality Model (RZWQM) to examine N losses with 0 (NRR) or 50% (RR) corn residue removal within a corn and soybean rotation over a 10-yr period. In general, all simulations used the same pre-plant or post-emergence N fertilizer rate (200 kg ha−1 yr−1). Simulated annual corn yields averaged 10.7 Mg ha−1 for the post emergence applications (NRRpost and RRpost), and 9.5 and 9.4 Mg ha−1 yr−1 for NRRpre and RRpre. Average total N input during corn years was 19.3 kg N ha−1 greater for NRRpre compared to RRpre due to additional N in surface residues, but drainage N loss was only 1.1 kg N ha−1 yr−1 greater for NRRpre. Post-emergence N application with no residue removal (NRRpost) reduced average drainage N loss by 16.5 kg ha−1 yr−1 compared to pre-plant N fertilization (NRRpre). The farm-gate net energy ratio was greatest for RRpost and lowest for NRRpre (14.1 and 10.4 MJ output per MJ input) while greenhouse gas intensity was lowest for RRpost and highest for NRRpre (11.7 and 17.3 g CO2-eq. MJ−1 output). Similar to published studies, the simulations showed little difference in N2O emissions between scenarios, decreased microbial immobilization for RR compared to NRR, and small soil carbon changes over the 10-yr simulation. In contrast to several previous modeling studies, the crop yield and N lost to drain flow were nearly the same between NRR and RR without supplemental N applied to replace N removed with corn stover. These results are important to optimizing the energy and nitrogen budgets associated with corn stover harvest and for developing a sustainable bioenergy industry.

The current or “conventional” paradigm for producing process energy in a biorefinery processing cellulosic biomass is on‐site energy recovery through combustion of residual solids and biogas generated by the process. Excess electricity is then exported, resulting in large greenhouse gas (GHG) credits. However, this approach will cause lifecycle GHG emissions of biofuels to increase as more renewable energy sources (wind, solar, etc.) participate in grid‐electricity generation, and the GHG credits from displacing fossil fuel decrease. To overcome this drawback, a decentralized (depot‐based) biorefinery can be integrated with a coal‐fired power plant near a large urban area. In an integrated, decentralized, depot‐based biorefinery (IDB), the residual solids are co‐fired with coal either in the adjacent power plant or in coal‐fired boilers elsewhere to displace coal. An IDB system does not rely on indirect GHG credits through grid‐electricity displacement. In an IDB system, biogas from the wastewater treatment facility is also upgraded to biomethane and used as a transportation biofuel. The GHG savings per unit of cropland in the IDB systems (2.7–2.9 MgCO2/ha) are 1.5–1.6 fold greater than those in a conventional centralized system (1.7–1.8 MgCO2/ha). Importantly, the biofuel selling price in the IDBs is lower by 28–30 cents per gasoline‐equivalent liter than in the conventional centralized system. Furthermore, the total capital investment per annual biofuel volume in the IDB is much lower (by ~80%) than that in the conventional centralized system. Therefore, utilization of biomethane and residual solids in the IDB systems leads to much lower biofuel selling prices and significantly greater GHG savings per unit of cropland participating in the biorefinery system compared to the conventional centralized biorefineries.

In this study, a cellulosome-producing yeast reaction system with cellulase and hemicellulase activities is developed for synergistic catalysis of steam-exploded corn stover. Three adaptor scaffoldins with divergent specificities serve to contain an extensive type and amount of catalytic subunits. The maximum ethanol concentration of engineered yeast strain was 0.92 g/l corresponding to 53.44% of the theoretical yield based on grams of ethanol produced per gram of consumed total sugar under 30 °C with agitation at 90 rpm after 96 h. Here, our elaborated structural organization presents an approach designed toward genetic engineering of S. cerevisiae, a widespread, industrially important microorganism, for improved lignocellulolytic potential and advanced capability of consolidated bioprocessing.

On account of complexities associated with commercial production of second-generation biofuels, comprehensive examinations are required to enhance the economic feasibility of biobutanol production from cellulosic compounds. As the most abundant crop residue in the US, corn stover is a readily available feedstock for biorefineries. However, there are few studies to evaluate the corn stover application in the large-scale biobutanol production. In this regard, in order to estimate the amount of collectible corn stover special to biobutanol production, a quantitate model was presented. In this model, the residue potential quantity, job creation, butanol blends potential quantity, greenhouse gases (GHG) emissions and social costs, forecasting future trends, economic evaluation, and risk analysis are considered. It was estimated that a total quantity of 84 million tonnes (Mt) of stover for the production of about 10.48 gigaliters (Gl) of biobutanol can potentially be collected. Around 87.4% of the total collectible residues is produced in the Midwest. A total of 81,000 jobs can be generated and Iowa can potentially create the most jobs. Furthermore, around 9.5 Gl of gasoline can be saved and about 64.6 Gl of butanol-gasoline blend (Bu16) can potentially be produced from corn residues in the US, which is equivalent to 11.8% of total domestic gasoline consumption. The average minimum selling price (MSP) in the Midwest was $5.76 and $4.05 per gallon depending on the feedstock price, and Illinois, Indiana, Iowa, Minnesota, Nebraska, and South Dakota were predicted to be very attractive in terms of lower selling prices.

Anaerobic digestion (AD) is one of the most sustainable methods for treating wastes and producing energy in the form of biogas. However, this process normally has a high content of water and low total solids (TS), which could be a challenge for regions with water scarcity or treating wastewater from the digestates. Dry fermentation or anaerobic digestion (Dry-AD) is a solid-state fermentation with high TS and is accelerating in the biogas industries. Dry-AD with high volumetric biogas productivity and high organic loading rate is an effective method for treating high solid content materials such as crop wastes. The present article is dedicated to reviewing methane production from industrial crops waste through Dry-AD. The major industrial crops such as corn stover, wheat straw, and sugarcane bagasse as well as their generated wastes, composition, and potential for bioenergy production are studied. Then, the Dry-AD process parameters, advantages, and challenges are described.

With South Korea’s limited capability of feed production because of its relatively small cultivable area, the country is pushed to depend on foreign feed imports despite the immensely fluctuating price of corn. Hence, intensive efforts to increase the total cultivable area in Korea like extending of farming to mountainous area is being practiced. Corn was planted in Goesan County, a mountainous area in the country. Grain and stover were harvested separately in three harvest periods: early-harvest (Aug 8), mid-harvest (Aug 18), and late-harvest (Aug 28). The nutrient composition such as dry matter (DM), crude protein (CP), crude fat (EE), organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF), and non-fibrous carbohydrates (NFC) was determined after harvest. Effective degradability (ED) of the major nutrients (DM, NDF, ADF, and CP) were measured through in vitro fermentation of rumen fluid from Hanwoo (Korean cattle). pH, ammonia-N concentration, volatile fatty acid (VFA) concentration, and gas production were periodically measured at 0, 3, 6, 12, 24, 48, and 72 h. Corn grain showed higher nutrient content and ED than stover. It also had higher gas production but its pH, ammonia-N, and total VFA concentration were lower than corn stover. The best nutrient composition of corn grain was observed in early-harvest (high CP, EE, NDF, OM, NFC, and low ADF). Early-harvest of corn grain also had high effective degradability of dry matter (EDDM), effective degradability of neutral detergent fiber (EDNDF), effective degradability of acid detergent fiber (EDADF), and total VFA concentration. On the other hand, the best nutrient composition of stover was observed in mid-harvest (high DM, CP, NDF, and low ADF). EDDM, EDNDF, and EDADF were pronounced in early-harvest and mid-harvest of stover but the latter showed high total VFA concentration. Hence, early and mid-harvested corn stover and grain in a mountainous area preserved their nutrients, which led to the effective degradation of major nutrients and high VFA production.

Corn (Zea mays L.) is grown across vast acreages producing massive quantities of stover making corn a desirable cellulosic bioenergy feedstock. Nitrous oxide (N₂O) is a potent greenhouse gas (GHG) so small changes in direct soil N₂O emissions may have substantial influence on global warming potential (GWP) from the agricultural sector. Harvesting stover alters soil properties such as soil moisture, oxygen availability, temperature, and substrate availability (C and N). Thus, harvesting stover might reduce soil N₂O emissions by reducing substrate and by warming and drying the soil. The goal of the study was to determine how harvesting corn stover altered soil N₂O emissions. Therefore, soil N₂O emissions were measured for four crop-years (planting to planting) in two independent studies, one in a field managed without tillage (NT1995) and the other was in a field tilled annually with a chisel plow (Chisel). Each field was in a corn–soybean (Glycine max L. [Merr.]) rotation, with (i) corn grain (Grain) only, (ii) grain plus about 50% of the stover harvested (Grain+Moderate), and (iii) grain plus harvesting as much stover as possible (Grain+Aggressive) treatments. Cumulative soil N₂O emissions did not differ among treatments in either field during any of the crop-years monitored. Flux events occurred corresponding to fertilizer applications and to spring freeze-thaw events. Cumulative fertilizer stimulated emissions tended to be greater for corn than soybean because of N-fertilizer application. These results are valuable to modelers for enhancing estimates of the N₂O component of the stover management C-footprint.

To date, information on biomass deconstruction and advanced biofuels production using pilot-scale pretreatments is scarce and typically derived from single feedstocks, making comparisons complicated. This work evaluates the effect of subjecting four different feedstocks (agave bagasse [AG], corn stover [CS], sugarcane bagasse [SC] and wheat straw [WS]) to pretreatment at 180 °C for 20 min in a 200 kg day−1 pilot-scale continuous tubular reactor constituted by three sequential stages (compression, autohydrolysis and steam explosion). Correlations between the structural changes and differences in digestibility on pretreated biomass were determined. It was determined that xylan removal by pretreatment generated more crystalline and energy dense materials, with higher lignin content and S/G ratio. Optimal reaction conditions for enzymatic saccharification of pretreated feedstocks at lower enzyme doses generated glucose conversions up to 80%. Finally, it was demonstrated that the yeast Rhodosporidium toruloides was able to grow in all hydrolysates, exhibiting simultaneous C5 and C6 sugar consumption and bisabolene production.