Environment. Sustainable development of the agricultural bio-economy

Discussion: Prioritize perennial grain development for sustainable food production and environmental benefits

Perennial grains have potential to contribute to ecological intensification of food production by enabling the direct harvest of human-edible crops without requiring annual cycles of disturbance and replanting. Studies of prototype perennial grains and other herbaceous perennials point to the ability of agroecosystems including these crops to protect water quality, enhance wildlife habitat, build soil quality, and sequester soil carbon. However, genetic improvement of perennial grain candidates has been hindered by limited investment due to uncertainty about whether the approach is viable. As efforts to develop perennial grain crops have expanded in past decades, critiques of the approach have arisen. With a recent report of perennial rice producing yields equivalent to those of annual rice over eight consecutive harvests, many theoretical concerns have been alleviated. Some valid questions remain over the timeline for new crop development, but we argue these may be mitigated by implementation of recent technological advances in crop breeding and genetics such as low-cost genotyping, genomic selection, and genome editing. With aggressive research investment in the development of new perennial grain crops, they can be developed and deployed to provide atmospheric greenhouse gas reductions.

Impacts on water quality in the peatland dominated catchment due to foreseen changes in Nordic Bioeconomy Pathways

The Nordic Bioeconomy Pathways (NBPs), conceptualized subsets of Shared Socioeconomic Pathways varying from environmentally friendly to open-market competition scenarios, can lead to plausible stressors in future for using bioresources. This study analysed the impacts of NBPs on hydrology and water quality based on two different land system management attributes: management strategy and a combination of reduced stand management and biomass removal at a catchment-scale projection. To understand the potential impacts of NBPs, the Simojoki catchment in northern Finland was chosen, as the catchment mainly covered peatland forestry. The analysis integrated a stakeholder-driven questionnaire, the Finnish Forest dynamics model, and Soil and Water Assessment Tool to build NBP scenarios, including Greenhouse gas emission pathways, for multiple management attributes to simulate flows, nutrients, and suspended solids (SS). For the catchment management strategy, an annual decrease in nutrients was observed for sustainability and business-as-usual scenarios. Reduced stand management and biomass removal also led to decreased export of nutrients and SS for the same scenarios, whereas, in other NBPs, the export of nutrients and SS increased with decreased evapotranspiration. Although the study was investigated at a local scale, based on the current political and socioeconomic situation, the approach used in this study can be outscaled to assess the use of forest and other bioresources in similar catchments.

Phytochemical Profile and In Vitro Bioactivities of Plant-Based By-Products in View of a Potential Reuse and Valorization

Wastes and by-products of plant origin are of particular interest to develop a circular economy approach, which attempts to turn them into resources. In this work, thirty-seven neglected plant matrices, including agricultural residues, pest plants, and by-products from the herbal and food industry were extracted and tested for their in vitro anti-tyrosinase, antioxidant, and antibacterial activity against the phytopathogens Pseudomonas syringae pv. syringae ATCC 19310 and Clavibacter michiganensis subsp. nebraskense ATCC 27822. Antioxidant activity ranged from 0.3 to 5 mg of Tr. eq/mL of plant extract, and extract of Castanea sativa pericarp (Csp), Rosa damascena buds (post-distillation) (Rod), and Prunus amygdalus exocarp and mesocarp (Pam) were the most powerful ones. Csp was also capable of inhibiting tyrosinase (IC₅₀ = 16.5 µg/mL), as well as three distillation by-products, namely: Cupressus sempervirens (Css) (IC₅₀ = 95.5 µg/mL), Salvia officinalis (Sco) (IC₅₀ = 87.6 µg/mL), and Helichrysum italicum (Hei) (IC₅₀ = 90.1 µg/mL). Five residues from distillation showed antibacterial activity against C. michiganensis (MICs ranging from 0.125 to 1 mg/mL), namely: Salvia sclarea L. (Sas), Salvia rosmarinus Schleid (Sar), Sco, Hei, and Css. The ¹H NMR fingerprinting of the bioactive matrices was acquired, detecting primary and secondary metabolites (rosmarinic acid, shikimic acid, sclareol, and hydroxycinnamic acids).

Effect of alfalfa on subsurface (tile) nitrogen and phosphorus loss in Ohio, USA

Growing annual crops such as corn (Zea mays L.) can lead to considerable nutrient losses through subsurface drainage in agricultural fields, posing a serious threat to surface water quality in the midwestern United States. Perennial crops have the potential to reduce these nutrient losses. However, more comprehensive data are needed on the nutrient loss effect of perennial crops. We examined the effect of alfalfa (Medicago sativa L.) on nitrate-nitrogen (NO₃ ^- -N), total nitrogen (TN), dissolved reactive phosphorus (DRP), and total phosphorus (TP) in subsurface drainage using a before-after-control-impact (BACI) experimental design with one control field (with annual crops) and one impact field (with alfalfa) each on two farms (Sites A and B) located in northwestern Ohio. The "Before" period (prior to planting alfalfa at the impact field) extended for 4 yr (2013-2017) at Site A and 6 yr (2011-2017) at Site B; the "After" period extended for an additional 2 yr at both sites. Reductions in the mean monthly discharge and loads of NO₃ ^- -N, TN, DRP, and TP were significant at Site A, whereas the only significant change at site B was a reduction in the mean monthly TP load. Significant reductions in NO₃ ^- -N loads were observed during spring and winter at Site A. In addition, alfalfa reduced the variability of discharge and nutrient loads through subsurface drainage at both sites. Our findings suggest that introducing alfalfa into annual crop rotations has the potential to reduce subsurface nutrient loads and increase the resiliency of agricultural systems.

Cropping practices manipulate soil bacterial structure and functions on the Qinghai-Tibet Plateau

There is an increasing awareness of the adverse environmental effects of the intensive practices used in modern crop farming, such as those that cause greenhouse gas emissions and nutrient leaching. Harnessing beneficial microbes by changing planting practices presents a promising strategy for optimizing plant growth and agricultural sustainability. However, the characteristics of soil microorganisms under different planting patterns remain uncertain. We conducted a study of soil bacterial structure and function under monoculture vs. polyculture planting regimes using 16S rRNA gene sequencing on the Qinghai-Tibet Plateau. We observed substantial variations in bacterial richness, diversity, and relative abundances of taxa between gramineous and leguminous monocultures, as well as between gramineae-legume polycultures. The number of operational taxonomic units and alpha and beta diversity were markedly higher in the leguminous monocultures than in the gramineous monocultures; conversely, network analysis revealed that the interactions among the bacterial genera in the gramineous monocultures were more complex than those in the other two planting regimes. Moreover, nitrogen fixation, soil detoxification, and productivity were increased under the gramineous monocultures; more importantly, low soil-borne diseases (e.g., animals parasitic or symbiont) also facilitated strongly suppressive effects toward soil-borne pathogens. Nevertheless, the gramineae-legume polycultures were prone to nitrate seepage contamination, and leguminous monocultures exhibited strong denitrification effects. These results revealed that the gramineous monoculture is a more promising cropping pattern on the Qinghai-Tibetan Plateau. Understanding the bacterial distribution patterns and interactions of crop-sensitive microbes presents a basis for developing microbial management strategies for smart farming.

Sustainable Development of Agriculture in Member States of the European Union

The main aim of this study was to evaluate the sustainable development of agriculture in the member states of the European Union (EU). Sustainable development is the main objective of Polish agriculture. Sustainable development encompasses three pillars: economic, social and environmental. In recent years, Polish agriculture has undergone a considerable change to integrate and adapt the agricultural sector to the EU standards. The achievement of the sustainable development goals in European agriculture was evaluated based on the Eurostat data as well as the analysis of the literature. The discussion on sustainable development of agriculture is rich. However, little attention is paid to the measurement of sustainable development. Our intention was to fill in the gap in the literature and provide a method to evaluate sustainable development. The paper contributes to the measurement of sustainable development based on Hellwig’s method. The changes in sustainable agricultural development were assessed with an index that was normalized with the zero unitarization method. In the first step, descriptive statistics for the variables applied in the process of calculating the sustainable development index were analyzed. The taxonomic measure of development (TMD) was then calculated for the economic, social and environmental dimensions of sustainable development. In the following stage, 27 EU member states were divided into sustainable development classes based on the mean values of the TMD for each of the three pillars of sustainability. The conducted research revealed changes between the European Union countries in terms of sustainable development. In 2018, the highest values of the sustainable development index were noted in the Netherlands, Germany, France and the United Kingdom.

Multi‐population puma connectivity could restore genomic diversity to at‐risk coastal populations in California

Urbanization is decreasing wildlife habitat and connectivity worldwide, including for apex predators, such as the puma (Puma concolor). Puma populations along California's central and southern coastal habitats have experienced rapid fragmentation from development, leading to calls for demographic and genetic management. To address urgent conservation genomic concerns, we used double‐digest restriction‐site associated DNA (ddRAD) sequencing to analyze 16,285 genome‐wide single‐nucleotide polymorphisms (SNPs) from 401 pumas sampled broadly across the state. Our analyses indicated support for 4–10 geographically nested, broad‐ to fine‐scale genetic clusters. At the broadest scale, the four genetic clusters had high genetic diversity and exhibited low linkage disequilibrium, indicating that pumas have retained genomic diversity statewide. However, multiple lines of evidence indicated substructure, including 10 finer‐scale genetic clusters, some of which exhibited fixed alleles and linkage disequilibrium. Fragmented populations along the Southern Coast and Central Coast had particularly low genetic diversity and strong linkage disequilibrium, indicating genetic drift and close inbreeding. Our results demonstrate that genetically at risk populations are typically nested within a broader‐scale group of interconnected populations that collectively retain high genetic diversity and heterogenous fixations. Thus, extant variation at the broader scale has potential to restore diversity to local populations if management actions can enhance vital gene flow and recombine locally sequestered genetic diversity. These state‐ and genome‐wide results are critically important for science‐based conservation and management practices. Our nested population genomic analysis highlights the information that can be gained from population genomic studies aiming to provide guidance for the conservation of fragmented populations.

A Brief Journey into the History of and Future Sources and Uses of Fatty Acids

Fats and lipids have always had a primary role in the history of humankind, from ancient civilisations to the modern and contemporary time, going from domestic and cosmetic uses, to the first medical applications and later to the large-scale industrial uses for food, pharmaceutical, cosmetics, and biofuel production. Sources and uses of those have changed during time following the development of chemical sciences and industrial technological advances. Plants, fish, and animal fats have represented the primary source of lipids and fats for century. Nowadays, the use of fatty acid sources has taken a turn: industries are mainly interested in polyunsaturated fatty acids (PUFAs), which have beneficial properties in human health; and also, for high-value fatty acids product for innovative and green production of biofuel and feedstocks. Thus, the constant increase in demand of fatty acids, the fact that marine and vegetable sources are not adequate to meet the high level of fatty acids required worldwide and climate change, have determined the necessity of the search for renewable and sustainable sources for fatty acids. Biotechnological advances and bioengineering have started looking at the genetic modification of algae, bacteria, yeasts, seeds, and plants to develop cell factory able to produce high value fatty acid products in a renewable and sustainable manner. This innovative approach applied to FA industry is a peculiar example of how biotechnology can serve as a powerful mean to drive the production of high value fatty acid derivatives on the concept of circular bioeconomy, based on the reutilisation of organic resources for alternative and sustainable productive patterns that are environmentally friendly.

Development of whole-genome prediction models to increase the rate of genetic gain in intermediate wheatgrass (Thinopyrum intermedium) breeding

The development of perennial grain crops is driven by the vision of simultaneous food production and enhanced ecosystem services. Typically, perennial crops like intermediate wheatgrass (IWG)[Thinopyrum intermedium (Host) Barkworth & D.R Dewey] have low seed yield and other detrimental traits. Next-generation sequencing has made genomic selection (GS) a tractable and viable breeding method. To investigate how an IWG breeding program may use GS, we evaluated 3,658 genets over 2 yr for 46 traits to build a training population. Six statistical models were used to evaluate the non-replicated data, and a model using autoregressive order 1 (AR1) spatial correction for rows and columns combined with the genomic relationship matrix provided the highest estimates of heritability. Genomic selection models were built from 18,357 single nucleotide polymorphism markers via genotyping-by-sequencing, and a 20-fold cross-validation showed high predictive ability for all traits (r > .80). Predictive abilities improved with increased training population size and marker numbers, even with larger amounts of missing data per marker. On the basis of these results, we propose a GS breeding method that is capable of completing one cycle per year compared with a minimum of 2 yr per cycle with phenotypic selection. We estimate that this breeding approach can increase the rate of genetic gain up to 2.6× above phenotypic selection for spike yield in IWG, allowing GS to enable rapid domestication and improvement of this crop. These breeding methods should be transferable to other species with similar long breeding cycles or limited capacity for replicated observations.

Do Students With Different Majors Have Different Personality Traits? Evidence From Two Chinese Agricultural Universities

This paper explores whether a Student’s choice of major leads to certain personality traits and the reasons for this phenomenon. Specifically, we look at evidence from two Chinese universities, both of which specialize in agricultural studies. Using the Sixteen Personality Factor (16PF) questionnaire and the Neuroticism Extraversion Openness Five-Factor Inventory (NEO-FFI) questionnaire, we collected data from two groups of students: those who study agriculture-related majors (ARM), and those who study non-agriculture-related majors (NARM). The surveys all showed no significant change in personality traits during Students’ freshman year. However, after 3 years of university study, significant personality trait changes were noted between seniors in the ARM and NARM groups. Whereas ARM seniors tended to be socially shy and lower in communicative competence, NARM seniors were better at expressing themselves and communicating with others. Although a Student’s choice of profession has an influence on their personality traits, it is not the only factor. The differences between ARM and NARM training models and curricula are also undoubtedly significant. Moreover, the bias against ARM in Chinese society further magnifies the differences in personality traits among students with different majors.

Potential impacts of a future Nordic bioeconomy on surface water quality

Nordic water bodies face multiple stressors due to human activities, generating diffuse loading and climate change. The 'green shift' towards a bio-based economy poses new demands and increased pressure on the environment. Bioeconomy-related pressures consist primarily of more intensive land management to maximise production of biomass. These activities can add considerable nutrient and sediment loads to receiving waters, posing a threat to ecosystem services and good ecological status of surface waters. The potential threats of climate change and the 'green shift' highlight the need for improved understanding of catchment-scale water and element fluxes. Here, we assess possible bioeconomy-induced pressures on Nordic catchments and associated impacts on water quality. We suggest measures to protect water quality under the 'green shift' and propose 'road maps' towards sustainable catchment management. We also identify knowledge gaps and highlight the importance of long-term monitoring data and good models to evaluate changes in water quality, improve understanding of bioeconomy-related impacts, support mitigation measures and maintain ecosystem services.

Biotechnology and Bioprocesses: Their Contribution to Sustainability

Significant advancements in biotechnology have resulted in the development of numerous fundamental bioprocesses, which have consolidated research and development and industrial progress in the field. These bioprocesses are used in medical therapies, diagnostic and immunization procedures, agriculture, food production, biofuel production, and environmental solutions (to address water-, soil-, and air-related problems), among other areas. The present study is a first approach toward the identification of scientific and technological bioprocess trajectories within the framework of sustainability. The method included a literature search (Scopus), a patent search (Patentscope), and a network analysis for the period from 2010 to 2019. Our results highlight the main technological sectors, countries, institutions, and academic publications that carry out work or publish literature related to sustainability and bioprocesses. The network analysis allowed for the identification of thematic clusters associated with sustainability and bioprocesses, revealing different related scientific topics. Our conclusions confirm that biotechnology is firmly positioned as an emerging knowledge area. Its dynamics, development, and outcomes during the study period reflect a substantial number of studies and technologies focused on the creation of knowledge aimed at improving economic development, environmental protection, and social welfare.

Green Innovation Areas—En Route to Sustainability for Shrinking Cities?

Green Innovation Areas have been developed in the US context of urban development in order to jump-start innovative solutions in abandoned areas. Prospective types of uses in these areas are not predetermined, but should be experimental and innovative. So far they can comprise vast greenhouse uses to less extensive clover fields, but their potential is not yet fully discovered. Implementing new and innovative economic uses in urban areas is relatively new in research for urban areas, in particular, when development types like bioeconomy are implemented. The joint German–Mexican research presented in this article aims at exploring the use of vacant inner urban spaces as Green Innovation Areas—discussing their potentials for sustainable development of shrinking cities.

Synthesis of MCM-41-Supported Metal Catalysts in Deep Eutectic Solvent for the Conversion of Carbohydrates into 5-Hydroxymethylfurfural

A series of MCM-41 supported metal catalysts (denoted M/D41) were prepared by using the deep eutectic solvent (DES)-mediated ionothermal synthesis strategy. Al/D41 was found to have excellent performance in the conversion of carbohydrates into 5-hydroxymethylfurfural (HMF). Furthermore, the production of HMF from glucose could be performed at high concentrations in choline chloride aqueous solution (CAS; 32 wt %, relative to the reaction phase) and as a result, CAS is a more promising solvent than water and DES for HMF production.

Multiple levers for overcoming the recalcitrance of lignocellulosic biomass

BACKGROUND

The recalcitrance of cellulosic biomass is widely recognized as a key barrier to cost-effective biological processing to fuels and chemicals, but the relative impacts of physical, chemical and genetic interventions to improve biomass processing singly and in combination have yet to be evaluated systematically. Solubilization of plant cell walls can be enhanced by non-biological augmentation including physical cotreatment and thermochemical pretreatment, the choice of biocatalyst, the choice of plant feedstock, genetic engineering of plants, and choosing feedstocks that are less recalcitrant natural variants. A two-tiered combinatoric investigation of lignocellulosic biomass deconstruction was undertaken with three biocatalysts (Clostridium thermocellum, Caldicellulosiruptor bescii, Novozymes Cellic^® Ctec2 and Htec2), three transgenic switchgrass plant lines (COMT, MYB4, GAUT4) and their respective nontransgenic controls, two Populus natural variants, and augmentation of biological attack using either mechanical cotreatment or cosolvent-enhanced lignocellulosic fractionation (CELF) pretreatment.

RESULTS

In the absence of augmentation and under the conditions tested, increased total carbohydrate solubilization (TCS) was observed for 8 of the 9 combinations of switchgrass modifications and biocatalysts tested, and statistically significant for five of the combinations. Our results indicate that recalcitrance is not a trait determined by the feedstock only, but instead is coequally determined by the choice of biocatalyst. TCS with C. thermocellum was significantly higher than with the other two biocatalysts. Both CELF pretreatment and cotreatment via continuous ball milling enabled TCS in excess of 90%.

CONCLUSION

Based on our results as well as literature studies, it appears that some form of non-biological augmentation will likely be necessary for the foreseeable future to achieve high TCS for most cellulosic feedstocks. However, our results show that this need not necessarily involve thermochemical processing, and need not necessarily occur prior to biological conversion. Under the conditions tested, the relative magnitude of TCS increase was augmentation > biocatalyst choice > plant choice > plant modification > plant natural variants. In the presence of augmentation, plant modification, plant natural variation, and plant choice exhibited a small, statistically non-significant impact on TCS.

Towards a sustainable biobased industry - Highlighting the impact of extremophiles

The transition of the oil-based economy towards a sustainable economy completely relying on biomass as renewable feedstock requires the concerted action of academia, industry, politics and civil society. An interdisciplinary approach of various fields such as microbiology, molecular biology, chemistry, genetics, chemical engineering and agriculture in addition to cross-sectional technologies such as economy, logistics and digitalization is necessary to meet the future global challenges. The genomic era has contributed significantly to the exploitation of naturés biodiversity also from extreme habitats. By applying modern technologies it is now feasible to deliver robust enzymes (extremozymes) and robust microbial systems that are active at temperatures up to 120°C, at pH 0 and 12 and at 1000bar. In the post-genomic era, different sophisticated "omics" analyses will allow the identification of countless novel enzymes regardless of the lack of cultivability of most microorganisms. Furthermore, elaborate protein-engineering methods are clearing the way towards tailor-made robust biocatalysts. Applying environmentally friendly and efficient biological processes, terrestrial and marine biomass can be converted to high value products e.g. chemicals, building blocks, biomaterials, pharmaceuticals, food, feed and biofuels. Thus, further application of extremophiles has the potential to improve sustainability of existing biotechnological processes towards a greener biobased industry.

Perennial Grain and Oilseed Crops

Historically, agroecosystems have been designed to produce food. Modern societies now demand more from food systems-not only food, fuel, and fiber, but also a variety of ecosystem services. And although today's farming practices are producing unprecedented yields, they are also contributing to ecosystem problems such as soil erosion, greenhouse gas emissions, and water pollution. This review highlights the potential benefits of perennial grains and oilseeds and discusses recent progress in their development. Because of perennials' extended growing season and deep root systems, they may require less fertilizer, help prevent runoff, and be more drought tolerant than annuals. Their production is expected to reduce tillage, which could positively affect biodiversity. End-use possibilities involve food, feed, fuel, and nonfood bioproducts. Fostering multidisciplinary collaborations will be essential for the successful integration of perennials into commercial cropping and food-processing systems.

Toward a microbial Neolithic revolution in buildings

The Neolithic revolution--the transition of our species from hunter and gatherer to cultivator--began approximately 14,000 years ago and is essentially complete for macroscopic food. Humans remain largely pre-Neolithic in our relationship with microbes but starting with the gut we continue our hundred-year project of approaching the ability to assess and cultivate benign microbiomes in our bodies. Buildings are analogous to the body and it is time to ask what it means to cultivate benign microbiomes in our built environment. A critical distinction is that we have not found, or invented, niches in buildings where healthful microbial metabolism occurs and/or could be cultivated. Key events affecting the health and healthfulness of buildings such as a hurricane leading to a flood or a burst pipe occur only rarely and unpredictably. The cause may be transient but the effects can be long lasting and, e.g., for moisture damage, cumulative. Non-invasive "building tomography" could find moisture and "sentinel microbes" could record the integral of transient growth. "Seed" microbes are metabolically inert cells able to grow when conditions allow. All microbes and their residue present actinic molecules including immunological epitopes (molecular shapes). The fascinating hygiene and microbial biodiversity hypotheses propose that a healthy immune system requires exposure to a set of microbial epitopes that is rich in diversity. A particular conjecture is that measures of the richness of diversity derived from microbiome next-generation sequencing (NGS) can be mechanistically coupled to--rather than merely correlated with some measures of--human health. These hypotheses and conjectures inspire workers and funders but an alternative is also consequent to the first Neolithic revolution: That the genetic uniformity of contemporary foods may also decrease human exposure to molecular biodiversity in a heath-relevant manner. Understanding the consequences--including the unintended consequences of the first Neolithic revolution--will inform and help us benignly implement the second--the microbial--Neolithic revolution.

Soil Functional Zone Management: A Vehicle for Enhancing Production and Soil Ecosystem Services in Row-Crop Agroecosystems

There is increasing global demand for food, bioenergy feedstocks and a wide variety of bio-based products. In response, agriculture has advanced production, but is increasingly depleting soil regulating and supporting ecosystem services. New production systems have emerged, such as no-tillage, that can enhance soil services but may limit yields. Moving forward, agricultural systems must reduce trade-offs between production and soil services. Soil functional zone management (SFZM) is a novel strategy for developing sustainable production systems that attempts to integrate the benefits of conventional, intensive agriculture, and no-tillage. SFZM creates distinct functional zones within crop row and inter-row spaces. By incorporating decimeter-scale spatial and temporal heterogeneity, SFZM attempts to foster greater soil biodiversity and integrate complementary soil processes at the sub-field level. Such integration maximizes soil services by creating zones of 'active turnover', optimized for crop growth and yield (provisioning services); and adjacent zones of 'soil building', that promote soil structure development, carbon storage, and moisture regulation (regulating and supporting services). These zones allow SFZM to secure existing agricultural productivity while avoiding or minimizing trade-offs with soil ecosystem services. Moreover, the specific properties of SFZM may enable sustainable increases in provisioning services via temporal intensification (expanding the portion of the year during which harvestable crops are grown). We present a conceptual model of 'virtuous cycles', illustrating how increases in crop yields within SFZM systems could create self-reinforcing feedback processes with desirable effects, including mitigation of trade-offs between yield maximization and soil ecosystem services. Through the creation of functionally distinct but interacting zones, SFZM may provide a vehicle for optimizing the delivery of multiple goods and services in agricultural systems, allowing sustainable temporal intensification while protecting and enhancing soil functioning.

Bioenergy and African transformation

Among the world's continents, Africa has the highest incidence of food insecurity and poverty and the highest rates of population growth. Yet Africa also has the most arable land, the lowest crop yields, and by far the most plentiful land resources relative to energy demand. It is thus of interest to examine the potential of expanded modern bioenergy production in Africa. Here we consider bioenergy as an enabler for development, and provide an overview of modern bioenergy technologies with a comment on application in an Africa context. Experience with bioenergy in Africa offers evidence of social benefits and also some important lessons. In Brazil, social development, agricultural development and food security, and bioenergy development have been synergistic rather than antagonistic. Realizing similar success in African countries will require clear vision, good governance, and adaptation of technologies, knowledge, and business models to myriad local circumstances. Strategies for integrated production of food crops, livestock, and bioenergy are potentially attractive and offer an alternative to an agricultural model featuring specialized land use. If done thoughtfully, there is considerable evidence that food security and economic development in Africa can be addressed more effectively with modern bioenergy than without it. Modern bioenergy can be an agent of African transformation, with potential social benefits accruing to multiple sectors and extending well beyond energy supply per se. Potential negative impacts also cut across sectors. Thus, institutionally inclusive multi-sector legislative structures will be more effective at maximizing the social benefits of bioenergy compared to institutionally exclusive, single-sector structures.

Threshold dynamics in soil carbon storage for bioenergy crops

Because of increasing demands for bioenergy, a considerable amount of land in the midwestern United States could be devoted to the cultivation of second-generation bioenergy crops, such as switchgrass and miscanthus. The foliar carbon/nitrogen ratio (C/N) in these bioenergy crops at harvest is significantly higher than the ratios in replaced crops, such as corn or soybean. We show that there is a critical soil organic matter C/N ratio, where microbial biomass can be impaired as microorganisms become dependent upon net immobilization. The simulation results show that there is a threshold effect in the amount of aboveground litter input in the soil after harvest that will reach a critical organic matter C/N ratio in the soil, triggering a reduction of the soil microbial population, with significant consequences in other microbe-related processes, such as decomposition and mineralization. These thresholds are approximately 25 and 15% of aboveground biomass for switchgrass and miscanthus, respectively. These results suggest that values above these thresholds could result in a significant reduction of decomposition and mineralization, which, in turn, would enhance the sequestration of atmospheric carbon dioxide in the topsoil and reduce inorganic nitrogen losses when compared to a corn-corn-soybean rotation.

Heterologous complementation of a pyrF deletion in Caldicellulosiruptor hydrothermalis generates a new host for the analysis of biomass deconstruction

BACKGROUND

Members of the thermophilic, anaerobic Gram-positive bacterial genus Caldicellulosiruptor grow optimally at 65 to 78°C and degrade lignocellulosic biomass without conventional pretreatment. Decomposition of complex cell wall polysaccharides is a major bottleneck in the conversion of plant biomass to biofuels and chemicals, and conventional biomass pretreatment includes exposure to high temperatures, acids, or bases as well as enzymatic digestion. Members of this genus contain a variety of glycosyl hydrolases, pectinases, and xylanases, but the contribution of these individual enzymes to biomass deconstruction is largely unknown. C. hydrothermalis is of special interest because it is the least cellulolytic of all the Caldicellulosiruptor species so far characterized, making it an ideal naïve system to study key cellulolytic enzymes from these bacteria.

RESULTS

To develop methods for genetic manipulation of C. hydrothermalis, we selected a spontaneous deletion of pyrF, a gene in the pyrimidine biosynthetic pathway, resulting in a strain that was a uracil auxotroph resistant to 5-fluoroorotic acid (5-FOA). This strain allowed the selection of prototrophic transformants with either replicating or non-replicating plasmids containing the wild-type pyrF gene. Counter-selection of the pyrF wild-type allele on non-replicating vectors allowed the construction of chromosomal deletions. To eliminate integration of the non-replicating plasmid at the pyrF locus in the C. hydrothermalis chromosome, we used the non-homologous Clostridium thermocellum wild-type pyrF allele to complement the C. hydrothermalis pyrF deletion. The autonomously replicating shuttle vector was maintained at 25 to 115 copies per chromosome. Deletion of the ChyI restriction enzyme in C. hydrothermalis increased the transformation efficiency by an order of magnitude and demonstrated the ability to construct deletions and insertions in the genome of this new host.

CONCLUSIONS

The use of C. hydrothermalis as a host for homologous and heterologous expression of enzymes important for biomass deconstruction will enable the identification of enzymes that contribute to the special ability of these bacteria to degrade complex lignocellulosic substrates as well as facilitate the construction of strains to improve and extend their substrate utilization capabilities.

Food sovereignty: an alternative paradigm for poverty reduction and biodiversity conservation in Latin America

Strong feedback between global biodiversity loss and persistent, extreme rural poverty are major challenges in the face of concurrent food, energy, and environmental crises. This paper examines the role of industrial agricultural intensification and market integration as exogenous socio-ecological drivers of biodiversity loss and poverty traps in Latin America. We then analyze the potential of a food sovereignty framework, based on protecting the viability of a diverse agroecological matrix while supporting rural livelihoods and global food production. We review several successful examples of this approach, including ecological land reform in Brazil, agroforestry, milpa, and the uses of wild varieties in smallholder systems in Mexico and Central America. We highlight emergent research directions that will be necessary to assess the potential of the food sovereignty model to promote both biodiversity conservation and poverty reduction.

Field-level financial assessment of contour prairie strips for enhancement of environmental quality

The impacts of strategically located contour prairie strips on sediment and nutrient runoff export from watersheds maintained under an annual row crop production system have been studied at a long-term research site in central Iowa. Data from 2007 to 2011 indicate that the contour prairie strips utilized within row crop-dominated landscapes have greater than proportionate and positive effects on the functioning of biophysical systems. Crop producers and land management agencies require comprehensive information about the Best Management Practices with regard to performance efficacy, operational/management parameters, and the full range of financial parameters. Here, a farm-level financial model assesses the establishment, management, and opportunity costs of contour prairie strips within cropped fields. Annualized, depending on variable opportunity costs the 15-year present value cost of utilizing contour prairie strips ranges from $590 to $865 ha(-1) year(-1) ($240-$350 ac(-1) year(-1)). Expressed in the context of "treatment area" (e.g., in this study 1 ha of prairie treats 10 ha of crops), the costs of contour prairie strips can also be viewed as $59 to about $87 per treated hectare ($24-$35 ac(-1)). If prairie strips were under a 15-year CRP contract, total per acre cost to farmers would be reduced by over 85 %. Based on sediment, phosphorus, and nitrogen export data from the related field studies and across low, medium, and high land rent scenarios, a megagram (Mg) of soil retained within the watershed costs between $7.79 and $11.46 mg(-1), phosphorus retained costs between $6.97 and $10.25 kg(-1), and nitrogen retained costs between $1.59 and $2.34 kg(-1). Based on overall project results, contour prairie strips may well become one of the key conservation practices used to sustain US Corn Belt agriculture in the decades to come.

Topographic and soil influences on root productivity of three bioenergy cropping systems

Successful modeling of the carbon (C) cycle requires empirical data regarding species-specific root responses to edaphic characteristics. We address this need by quantifying annual root production of three bioenergy systems (continuous corn, triticale/sorghum, switchgrass) in response to variation in soil properties across a toposequence within a Midwestern agroecosystem. Using ingrowth cores to measure annual root production, we tested for the effects of topography and 11 soil characteristics on root productivity. Root production significantly differed among cropping systems. Switchgrass root productivity was lowest on the floodplain position, but root productivity of annual crops was not influenced by topography or soil properties. Greater switchgrass root production was associated with high percent sand, which explained 45% of the variation. Percent sand was correlated negatively with soil C and nitrogen and positively with bulk density, indicating this variable is a proxy for multiple important soil properties. Our results suggest that easily measured soil parameters can be used to improve model predictions of root productivity in bioenergy switchgrass, but the edaphic factors we measured were not useful for predicting root productivity in annual crops. These results can improve C cycling modeling efforts by revealing the influence of cropping system and soil properties on root productivity.

Shifting lands: exploring Kansas farmer decision-making in an era of climate change and biofuels production

While farming has been the subject of frequent critical analysis with respect to its environmental impacts, including its greenhouse gas emissions, there has been relatively little consideration of the potentially positive role of agriculture in responding to a future greatly influenced by climate change. One possible realm for agriculture to contribute successfully to this future is through biofuels cultivation. This paper uses the state of Kansas as an example to examine factors that are influencing farmer decision-making during a time of heightened debates about climate and energy. Drawing on interviews with key informants and Kansas farmers, we apply and refine a conceptual model for understanding farmer decisions. We find that farmers have largely positive perceptions of the natural environment. Climate change, especially, is not a salient concern at this time. Factors that appear most likely to influence farmer decisions to adopt a new practice include the relative advantage of that practice and the ability to learn about and discuss it through existing social networks. Successful policy incentives must provide farmers with a continued sense of both independence and contribution to greater societal good.

Reduced nitrogen losses after conversion of row crop agriculture to perennial biofuel crops

Current biofuel feedstock crops such as corn lead to large environmental losses of N through nitrate leaching and NO emissions; second-generation cellulosic crops have the potential to reduce these N losses. We measured N losses and cycling in establishing miscanthus (), switchgrass ( L. fertilized with 56 kg N ha yr), and mixed prairie, along with a corn ( L.)-corn-soybean [ (L.) Merr.] rotation (corn fertilized at 168-202 kg N ha). Nitrous oxide emissions, soil N mineralization, mid-profile nitrate leaching, and tile flow and nitrate concentrations were measured. Perennial crops quickly reduced nitrate leaching at a 50-cm soil depth as well as concentrations and loads from the tile systems (year 1 tile nitrate concentrations of 10-15 mg N L declined significantly by year 4 in all perennial crops to <0.6 mg N L, with losses of <0.8 kg N ha yr). Nitrous oxide emissions were 2.2 to 7.7 kg N ha yr in the corn-corn-soybean rotation but were <1.0 kg N ha yr by year 4 in the perennial crops. Overall N balances (atmospheric deposition + fertilization + soybean N fixation - harvest, leaching losses, and NO emissions) were positive for corn and soybean (22 kg N ha yr) as well as switchgrass (9.7 kg N ha yr) but were -18 and -29 kg N ha yr for prairie and miscanthus, respectively. Our results demonstrate rapid tightening of the N cycle as perennial biofuel crops established on a rich Mollisol soil.

Predicting summer hypoxia in the northern Gulf of Mexico: redux

We report on the evolution and accuracy of a model used to predict the mid-summer area of hypoxia (oxygen ≤2 mg l(-1)) in the northern Gulf of Mexico, use it to test for impacts from the Deepwater Horizon oil spill (2010), and estimate the N loading that would meet a management goal. The prediction since 2000 were 100%±6% (μ±1 SE) of the actual value. The predicted in 2010 was 99% of that actual value, suggesting that the net effect of the 2010 oil spill on the hypoxic zone size was negligible. A tropical storm, however, may have reduced the potential size of the hypoxic zone. Lowering the May nitrogen load to about 70,000 mton N nitrate+nitrite would bring the model's predicted hypoxic zone size down to the management goal of 5000 km(2) and restore hypoxic waters to normoxic conditions.

Midwest U.S. landscape change to 2020 driven by biofuel mandates

Meeting future biofuel targets set by the 2007 Energy Independence and Security Act (EISA) will require a substantial increase in production of corn. The Midwest, which has the highest overall crop production capacity, is likely to bear the brunt of the biofuel-driven changes. In this paper, we set forth a method for developing a possible future landscape and evaluate changes in practices and production between base year (BY) 2001 and biofuel target (BT) 2020. In our BT 2020 Midwest landscape, a total of 25 million acres (1 acre = 0.40 ha) of farmland was converted from rotational cropping to continuous corn. Several states across the Midwest had watersheds where continuous corn planting increased by more than 50%. The output from the Center for Agriculture and Rural Development (CARD) econometric model predicted that corn grain production would double. In our study we were able to get within 2% of this expected corn production. The greatest increases in corn production were in the Corn Belt as a result of conversion to continuous corn planting. In addition to changes to cropping practices as a result of biofuel initiatives we also found that urban growth would result in a loss of over 7 million acres of productive farmland by 2020. We demonstrate a method which successfully combines economic model output with gridded land cover data to create a spatially explicit detailed classification of the landscape across the Midwest. Understanding where changes are likely to take place on the landscape will enable the evaluation of trade-offs between economic benefits and ecosystem services allowing proactive conservation and sustainable production for human well-being into the future.