Reporting on Marginal Lands for Bioenergy Feedstock Production: a Modest Proposal

Growing bioenergy feedstocks can provide a long-term sustainable production system for marginal land resources and is essential for minimizing food vs. fuel competition for prime croplands. However, the term “marginal” is too often used in research reports without being defined. We here suggest that clearly specifying the biophysical factors and agroeconomic context contributing to marginality will greatly enhance the utility and comparability of published research.     

Crop Residue Considerations for Sustainable Bioenergy Feedstock Supplies

The anticipated 2014 launch of three full-scale corn stover bioenergy conversion facilities is a strong US market signal that cellulosic feedstock supplies must increase dramatically to supply the required biomass in a sustainable manner. This overview highlights research conducted by the USDA-Agricultural Research Service Renewable Energy Assessment Project (now known as the Resilient Economic Agricultural Practices) team as part of the National Institute for Food and Agriculture Sun Grant Regional Feedstock Partnership Corn Stover team. Stover and grain yield, soil organic carbon, soil aggregation, greenhouse gas, energy content of the stover, and several other factors affecting the fledgling bioenergy industry are addressed in this special issue of the journal.     

Production of Napiergrass as a Bioenergy Feedstock Under Organic Versus Inorganic Fertilization in the Southeast USA

Napiergrass (Pennisetum purpureum Schum.) is a high-yielding perennial biomass crop that is well adapted to the Southeast USA where poultry litter is readily available. This research was conducted to compare biomass production and nutrient utilization of napiergrass fertilized with either poultry litter or inorganic fertilizer. Each spring, approximately 100 kg ha^?1 of N, 40 kg ha^?1 P, and 90 kg ha^?1 K were applied as poultry litter or equivalent inorganic fertilizer. Biomass was harvested each winter after senescence. For the first 2 years, dry matter yield did not differ among treatments, but in the third and fourth years, yields declined in all treatments and were lowest in the unfertilized treatment. Biomass N concentration and N removal were greatest in the inorganic treatment. In general, N removal exceeded the amount applied, suggesting that higher application rates may be necessary to maintain yields. Biomass P concentration and total P uptake were greatest in the litter fertilized treatment, demonstrating that napiergrass can remove some of the excess P from applied litter. Soil cores were taken periodically to assess changes in soil properties. After 2 years of production, soil pH in the surface layer (0–15 cm) was lower in the inorganic treatment than in the other treatments. After 4 years, total soil C had increased by an average of 3,180 kg ha^?1 though fertilizer treatments did not differ. Yield declined in all treatments after 4 years and N supplementation is recommended for production in upland fields.     

Economic Feasibility of Using Switchgrass Pasture to Produce Beef Cattle Gain and Bioenergy Feedstock

Integration of switchgrass (Panicum virgatum L.) into livestock production systems has potential to improve farm economics and encourage development of a biofuel industry in the Southern Great Plains. The objectives of this study were to determine the economics of seven alternative switchgrass grazing and bioenergy feedstock systems and to determine how sensitive the results are among the systems for a range of cattle and feedstock prices. Data were collected from a completely randomized designed grazing study in south-central Oklahoma in 2008, 2009, and 2010. Stocking density treatments [0, 2.5, 4.9 and 7.4 hd ha^?1] were randomly assigned to 12 0.81-ha switchgrass pastures. Using biological data from the field trial, economic data collected from the marketplace and assumptions about prices of bioenergy feedstock, seven production systems were simulated. The systems included no-graze feedstock only (NG/FS); graze lightly no feedstock (GL/NF); graze moderately no feedstock (GM/NF); graze heavily no feedstock H/NF)]; lightly grazed plus feedstock (GL/F); moderately grazed plus feedstock (GM/F); and heavily grazed plus feedstock (GH/F). Enterprise budgeting was used to compute expected net returns for the seven systems. Random-effects mixed ANOVA models were used to determine the effects of production system on yield, gain, and net return. At a feedstock price $0 Mg^?1, the GM/NF was the most profitable ($45 ha^?1) system. At feedstock prices of $55 and $83 Mg^?1, the GL/F system realized net returns of $232 and $523 ha^?1, respectively, and for feedstock prices >$83 Mg^?1, the NG/FS system was determined to be most economical.     

Economics of Alternative Fertilizer Supply Systems for Switchgrass Produced in Phosphorus-Deficient Soils for Bioenergy Feedstock

Limited information is available explaining the economics of supplying N and P fertilizers on established stands of switchgrass growing in phosphorus-deficient soils. The objective of this study was to determine the most economical fertilizer supply system for producing feedstock in phosphorus-deficient soil in the southern Great Plains. Data collected from field trials conducted at two locations in south-central Oklahoma along with prices quoted by local input suppliers and custom service providers and assumptions about the farm-gate price of feedstock were used to estimate expected values for production costs, gross revenue and net return to owner's labor, management, and overhead for eight fertilizer supply systems. The systems included a zero fertilizer check system (0/0), three P systems (0/34, 0/67, and 0/101), one N system (135/0), and three N and P systems (135/34, 135/67, and 135/101). Random-effects mixed ANOVA models were used to determine the effects of fertilizer system on the values of total cost and net return. For the base-case price scenario (feedstock, N and P prices of $110 Mg^?1 and $1.28 and 1.17 kg^?1, respectively), the 135/0 system was the most profitable system, producing 10.2 Mg of feedstock and $263 of net return per hectare. Economic results were most sensitive to the prices of feedstock, N and P. Net return was negative for all eight systems for the scenario where the farm-gate price of feedstock was relatively low ($55 Mg^?1) and prices for N and P were relatively high ($2.20 kg^?1).     

Changes in Polysomes of Black Locust Seedlings during Dehydration-Rehydration Cycles

Net assimilation, dark respiration and xylem pressure potential were followed through dehydration-rehydration cycles in black locust seedlings (Robinia pseudoacacia L.). Sucrose gradient profiles indicated the retention of polysomes during stress. RNase activity declined during dehydration but returned to pre-stress levels upon irrigation. Comparisons of black locust and corn polysomes during water stress are made.     

刺槐对3种抗生素敏感性的测定

匈牙利刺槐对卡那霉素不敏感,对G418敏感,而对潮霉素极为敏感.如以NPTII基因为刺槐基因工程的选择性标记基因,则G418是理想的抗生素抗性选择试剂;如用HPT基因,则潮霉素是合适的抗生素抗性选择试剂.     

Critical Review of Microalgae LCA Studies for Bioenergy Production

The cultivation of microalgae gained high attention within the last years because of their potential to substitute conventional bioenergy crops. To evaluate algal bioenergy production pathways already at an early stage, several life cycle assessment (LCA) studies have been performed, but their results and conclusions vary drastically. Against this background, this review gives a comparative analysis of 16 recent studies. To allow for a comparison, a meta-approach served to uniform the considered systems. System boundaries have been equalized and the energy return on investment (EROI) has been calculated for each study. Depending on the assumptions made on biomass productivity, lipid content, required energy, and the output of the system, the energetic performance was assessed. Large variations from 0.01 to 3.35 for the EROI could be derived.     

Ribosomal Changes during Induction of Cold Hardiness in Black Locust Seedlings

Protein synthesis has been implicated in the cold-hardening process. Ribosomes from cold hardy and nonhardy black locust (Robinia pseudoacacia L.) seedlings were compared to determine if cold acclimation is related to alteration of ribosomal structure. Ribosomal structure, as indicated by thermal melting profiles, appears to be altered during induction of hardiness. Two-dimensional polyacrylamide gel electrophoresis of ribosomal proteins indicates at least 17 proteins from hardy seedlings that are different from those of nonhardy seedlings. These different proteins may be partially responsible for the different thermal melting profiles observed.     

生物能源的几点新思考

对目前粮食生物能源和非粮原料生物能源发展过程中遇到的若干问题进行综述和探讨。生物能源的健康发展需要有多元化的观点、多元化的选择和多元化的目标。     

The Effects of Dehydration-Rehydration Cycles on Protein Synthesis of Black Locust Seedlings

Protein synthetic activity of polysomes isolated during dehydration-rehydration cycles of black locust seedlings (Robiniapseudoacacia L.) was investigated. Polysomes of black locust seedlings were reduced by only 20% during water stress and were capable of incorporating ³H-leucine into peptide chins. RNase activity increased during stress and declined following irrigation. The presence of a protective mechanism is suggested which, if present in other drought hardy species, could help to explain the ability of these species to withstand various levels of water stress.     

Global Potential of Rice Husk as a Renewable Feedstock for Ethanol Biofuel Production

The production of ethanol for the energy market has traditionally been from corn and sugar cane biomass. The use of such biomass as energy feedstocks has recently been criticised as ill-fated due to competitive threat against food supplies. At the same time, ethanol production from cellulosic biomass is becoming increasingly popular. In this paper, we analyse rice husk (RH) as a cellulosic feedstock for ethanol biofuel production on the ground of its abundance. The global potential production of bioethanol from RH is estimated herein and found to be in the order of 20.9 to 24.3 GL per annum, potentially satisfying around one fifth of the global ethanol biofuel demand for a 10% gasohol fuel blend. Furthermore, we show that this is especially advantageous for Asia, in particular, India and China, where economic growth and demand for energy are exploding.     

Soluble and Insoluble Protein Patterns during Induction of Freezing Tolerance in Black Locust Seedlings

Protein metabolism plays a major role in the development of freezing tolerance in plants. Soluble and insoluble protein concentrations were followed during induction of freezing tolerance in black locust (Robinia pseudoacacia L.) stem tissues. Soluble proteins were fractionated using two-dimensional polyacrylamide gel electrophoresis and examined for the presence of glycoprotein fractions. Soluble protein concentration remained relatively constant during early stages of induction of freezing tolerance but increased significantly during later stages, while insoluble protein concentration remained relatively constant throughout induction. A new soluble protein component appeared during later stages of induction and was identified as a glycoprotein. Some glycoproteins are known to have a high water-binding capacity, which could play a role in intracellular resistance to ice formation during development of freezing tolerance.     

Neural Control of Gas Exchange Patterns in Insects: Locust Density-Dependent Phases as a Test Case

The adaptive significance of discontinuous gas exchange cycles (DGC) in insects is contentious. Based on observations of DGC occurrence in insects of typically large brain size and often socially-complex life history, and spontaneous DGC in decapitated insects, the neural hypothesis for the evolution of DGC was recently proposed. It posits that DGC is a non-adaptive consequence of adaptive down-regulation of brain activity at rest, reverting ventilatory control to pattern-generating circuits in the thoracic ganglia. In line with the predictions of this new hypothesis, we expected a higher likelihood of DGC in the gregarious phase of the desert locust (Schistocerca gregaria, Orthoptera), which is characterized by a larger brain size and increased sensory sensitivity compared with the solitary phase. Furthermore, surgical severing of the neural connections between head and thoracic ganglia was expected to increase DGC prevalence in both phases, and to eliminate phase-dependent variation in gas exchange patterns. Using flow-through respirometry, we measured metabolic rates and gas exchange patterns in locusts at 30°C. In contrast to the predictions of the neural hypothesis, we found no phase-dependent differences in DGC expression. Likewise, surgically severing the descending regulation of thoracic ventilatory control did not increase DGC prevalence in either phase. Moreover, connective-cut solitary locusts abandoned DGC altogether, and employed a typical continuous gas exchange pattern despite maintaining metabolic rate levels of controls. These results are not consistent with the predictions of the neural hypothesis for the evolution of DGC in insects, and instead suggest neural plasticity of ventilatory control.     

Wastewater: A Potential Bioenergy Resource

Wastewaters are a rich source of nutrients for microorganisms. However, if left unattended the biodegradation may lead to severe environmental hazards. The wastewaters can thus be utilized for the production of various value added products including bioenergy (H₂ and CH₄). A number of studies have reported utilization of various wastewaters for energy production. Depending on the nature of the wastewater, different reactor configurations, wastewater and inoculum pretreatments, co-substrate utilizations along with other process parameters have been studied for efficient product formation. Only a few studies have reported sequential utilization of wastewaters for H₂ and CH₄ production despite its huge potential for complete waste degradation.     

Quantitative Sustainability Assessment of Seaweed Biomass as Bioethanol Feedstock

Since terrestrial biomass-based ethanol has environmental and economic vulnerability, seaweed-based bioethanol is emerging as a new biofuel. To investigate the sustainability of seaweeds as bioethanol feedstock, this study quantitatively assesses the energy, freshwater, and fertilizer requirements; land-related carbon balance; and bioethanol productivity of seaweed biomass through comparison with terrestrial biomass. Also, the metal resource potential of seaweeds is assessed because valuable metals can be recovered from seaweed fermentation residue. Compared to corn grain and stover, seaweeds exhibit competitive energy requirements and ethanol productivity. Seaweed cultivation does not incur carbon debt derived from land use change and requires less freshwater than corn grain but more than switchgrass in cultivation and fermentation. Seaweed cultivation also does not require fertilizer application despite the high content of nitrogen and phosphorus. Seaweeds exhibit high resource potential for gold and silver. Therefore, seaweed biomass has high potential as a sustainable bioethanol feedstock.