Carbon addition alters vegetation composition on ex-arable fields

1. Recent changes in European agricultural policy have led to measures to reverse the loss of species-rich grasslands through the creation of new areas on ex-arable land. Ex-arable soils are often characterized by high inorganic nitrogen (N) levels, which lead to the rapid establishment of annual and fast-growing perennial species during the initial phase of habitat creation. The addition of carbon (C) to the soil has been suggested as a countermeasure to reduce plant-available N and alter competitive interactions among plant species. 2. To test the effect of C addition on habitat creation on ex-arable land, an experiment was set up on two recently abandoned fields in Switzerland and on two 6-year-old restoration sites in the UK. Carbon was added as a mixture of either sugar and sawdust or wood chips and sawdust during a period of 2 years. The effects of C addition on soil parameters and vegetation composition were assessed during the period of C additions and 1 year thereafter. 3. Soil nitrate concentrations were reduced at all sites within weeks of the first C addition, and remained low until cessation of the C additions. The overall effect of C addition on vegetation was a reduction in above-ground biomass and cover. At the Swiss sites, the addition of sugar and sawdust led to a relative increase in legume and forb cover and to a decrease in grass cover. The soil N availability, composition of soil micro-organisms and vegetation characteristics continued to be affected after cessation of C additions. 4. Synthesis and applications. The results suggest that C addition in grassland restoration is a useful management method to reduce N availability on ex-arable land. Carbon addition alters the vegetation composition by creating gaps in the vegetation that facilitates the establishment of late-seral plant species, and is most effective when started immediately after the abandonment of arable fields and applied over several years.

Simulating the impact on health of internalising the cost of carbon in food prices combined with a tax on sugar-sweetened beverages

Rising greenhouse gas emissions (GHGEs) have implications for health and up to 30 % of emissions globally are thought to arise from agriculture. Synergies exist between diets low in GHGEs and health however some foods have the opposite relationship, such as sugar production being a relatively low source of GHGEs. In order to address this and to further characterise a healthy sustainable diet, we model the effect on UK non-communicable disease mortality and GHGEs of internalising the social cost of carbon into the price of food alongside a 20 % tax on sugar sweetened beverages (SSBs). Developing previously published work, we simulate four tax scenarios: (A) a GHGEs tax of £2.86/tonne of CO2 equivalents (tCO2e)/100 g product on all products with emissions greater than the mean across all food groups (0.36 kgCO2e/100 g); (B) scenario A but with subsidies on foods with emissions lower than 0.36 kgCO2e/100 g such that the effect is revenue neutral; (C) scenario A but with a 20 % sales tax on SSBs; (D) scenario B but with a 20 % sales tax on SSBs. An almost ideal demand system is used to estimate price elasticities and a comparative risk assessment model is used to estimate changes to non-communicable disease mortality. We estimate that scenario A would lead to 300 deaths delayed or averted, 18,900 ktCO2e fewer GHGEs, and £3.0 billion tax revenue; scenario B, 90 deaths delayed or averted and 17,100 ktCO2e fewer GHGEs; scenario C, 1,200 deaths delayed or averted, 18,500 ktCO2e fewer GHGEs, and £3.4 billion revenue; and scenario D, 2,000 deaths delayed or averted and 16,500 ktCO2e fewer GHGEs. Deaths averted are mainly due to increased fibre and reduced fat consumption; a SSB tax reduces SSB and sugar consumption. Incorporating the social cost of carbon into the price of food has the potential to improve health, reduce GHGEs, and raise revenue. The simple addition of a tax on SSBs can mitigate negative health consequences arising from sugar being low in GHGEs. Further conflicts remain, including increased consumption of unhealthy foods such as cakes and nutrients such as salt.

Enantioselective Intramolecular Michael Addition of Nitronates onto Conjugated Esters: Access to Cyclic γ-Amino Acids with up to Three Stereocenters

A highly stereoselective synthesis of conformationally constrained cyclic γ-amino acids has been devised. The key step involves an intramolecular cyclization of a nitronate onto a conjugated ester, promoted by a bifunctional thiourea catalyst. This methodology has been successfully applied to generate a variety of γ-amino acids, including some containing three contiguous stereocenters, with very high diastereoselectivity and excellent enantioselectivity. It is postulated that an interaction that is key to the success of the process is the simultaneous coordination of the thiourea functionality to both the conjugated ester and the nitronate. Finally, the synthetic utility of these compounds is demonstrated in the synthesis of two dipeptides derived from the C- and N-termini.

Microbial relatives of the seed storage proteins of higher plants: conservation of structure and diversification of function during evolution of the cupin superfamily.

This review summarizes the recent discovery of the cupin superfamily (from the Latin term "cupa," a small barrel) of functionally diverse proteins that initially were limited to several higher plant proteins such as seed storage proteins, germin (an oxalate oxidase), germin-like proteins, and auxin-binding protein. Knowledge of the three-dimensional structure of two vicilins, seed proteins with a characteristic beta-barrel core, led to the identification of a small number of conserved residues and thence to the discovery of several microbial proteins which share these key amino acids. In particular, there is a highly conserved pattern of two histidine-containing motifs with a varied intermotif spacing. This cupin signature is found as a central component of many microbial proteins including certain types of phosphomannose isomerase, polyketide synthase, epimerase, and dioxygenase. In addition, the signature has been identified within the N-terminal effector domain in a subgroup of bacterial AraC transcription factors. As well as these single-domain cupins, this survey has identified other classes of two-domain bicupins including bacterial gentisate 1, 2-dioxygenases and 1-hydroxy-2-naphthoate dioxygenases, fungal oxalate decarboxylases, and legume sucrose-binding proteins. Cupin evolution is discussed from the perspective of the structure-function relationships, using data from the genomes of several prokaryotes, especially Bacillus subtilis. Many of these functions involve aspects of sugar metabolism and cell wall synthesis and are concerned with responses to abiotic stress such as heat, desiccation, or starvation. Particular emphasis is also given to the oxalate-degrading enzymes from microbes, their biological significance, and their value in a range of medical and other applications.

A high efficiency technique for the generation of transgenic sugar beets from stomatal guard cells

An optimized protocol has been developed for the efficient and rapid genetic modification of sugar beet (Beta vulgaris L.). A polyethylene glycol-mediated DNA transformation technique could be applied to protoplast populations enriched specifically for a single totipotent cell type derived from stomatal guard cells, to achieve high transformation frequencies. Bialaphos resistance, conferred by the pat gene, produced a highly efficient selection system. The majority of plants were obtained within 8 to 9 weeks and were appropriate for plant breeding purposes. All were resistant to glufosinate-ammonium-based herbicides. Detailed genomic characterization has verified transgene integration, and progeny analysis showed Mendelian inheritance.

Effects of stabiliser addition and in-container sterilisation on selected properties of milk related to casein micelle stability

Different stabilising salts and calcium chloride were added to raw milk to evaluate changes in pH, ionic calcium, ethanol stability, casein micelle size and zeta potential. These milk samples were then sterilised at 121 °C for 15 min and stored for 6 months to determine how these properties changed. Addition of tri-sodium citrate (TSC) and di-sodium hydrogen phosphate (DSHP) to milk reduced ionic calcium, increased pH and increased ethanol stability in a concentration-dependent fashion. There was relatively little change in casein micelle size and a slight decrease in zeta potential. Sodium hexametaphosphate (SHMP) also reduced ionic calcium considerably, but its effect on pH was less noticeable. In contrast, sodium dihydrogen phosphate (SDHP) reduced pH but had little effect on ionic calcium. In-container sterilisation of these samples reduced pH, increased ethanol stability and increased casein micelle size, but had variable effects on ionic calcium; for DSHP and SDHP, ionic calcium decreased after sterilisation but, for SHMP, it remained little changed or increased. Milk containing 3.2 mM SHMP and more than 4.5 mM CaCl2 coagulated upon sterilisation. All other samples were stable but there were differences in browning, which increased in intensity as milk pH increased. Heat-induced sediment was not directly related to ionic calcium concentration, so reducing ionic calcium was not the only consideration in terms of improving heat stability. After 6 months of storage, the most acceptable product, in appearance, was that containing SDHP, as this minimised browning during sterilisation and further development of browning during storage.

Bayesian estimation and selection of nonlinear vector error correction models: The case of the sugar-ethanol-oil nexus in Brazil

Nonlinear adjustment toward long-run price equilibrium relationships in the sugar-ethanol-oil nexus in Brazil is examined. We develop generalized bivariate error correction models that allow for cointegration between sugar, ethanol, and oil prices, where dynamic adjustments are potentially nonlinear functions of the disequilibrium errors. A range of models are estimated using Bayesian Monte Carlo Markov Chain algorithms and compared using Bayesian model selection methods. The results suggest that the long-run drivers of Brazilian sugar prices are oil prices and that there are nonlinearities in the adjustment processes of sugar and ethanol prices to oil price but linear adjustment between ethanol and sugar prices.

Environmental and human health impacts of growing genetically modified herbicide-tolerant sugar beet: a life-cycle assessment

There is ongoing debate concerning the possible environmental and human health impacts of growing genetically modified (GM) crops. Here, we report the results of a life-cycle assessment (LCA) comparing the environmental and human health impacts of conventional sugar beet growing regimes in the UK and Germany with those that might be expected if GM herbicide-tolerant (to glyphosate) sugar beet is commercialized. The results presented for a number of environmental and human health impact categories suggest that growing the GM herbicide-tolerant crop would be less harmful to the environment and human health than growing the conventional crop, largely due to lower emissions from herbicide manufacture, transport and field operations. Emissions contributing to negative environmental impacts, such as global warming, ozone depletion, ecotoxicity of water and acidification and nutrification of soil and water, were much lower for the herbicide-tolerant crop than for the conventional crop. Emissions contributing to summer smog, toxic particulate matter and carcinogenicity, which have negative human health impacts, were also substantially lower for the herbicide-tolerant crop. The environmental and human health impacts of growing GM crops need to be assessed on a case-by-case basis using a holistic approach. LCA is a valuable technique for helping to undertake such assessments.

An application of life-cycle assessment for environmental planning and management: the potential environmental and human health impacts of growing genetically-modified herbicide-tolerant sugar beet

Life-Cycle Assessment (LCA) was used to assess the potential environmental and human health impacts of growing genetically-modified (GM), herbicide-tolerant sugar beet in the UK and Germany compared with conventional sugar beet varieties. The GM variety results in lower potential environmental impacts on global warming, airborne nutrification, ecotoxicity (of soil and water) and watercourse enrichment, and lower potential human health impacts in terms of production of toxic particulates, summer smog, carcinogens and ozone depletion. Although the overall contribution of GM sugar beet to reducing harmful emissions to the environment would be relatively small, the potential for GM crops to reduce pollution from agriculture, including diffuse water pollution, is highlighted.

In vitro evaluation of fibrolytic enzymes as additives for maize (Zea mays L.) silage - I. Effects of ensiling temperature, enzyme source and addition level

A series of experiments was completed to investigate the impact of addition of enzymes at ensiling on in vitro rumen degradation of maize silage. Two commercial products, Depot 40 (D, Biocatalysts Ltd., Pontypridd, UK) and Liquicell 2500 (L, Specialty Enzymes and Biochemicals, Fresno, CA, USA), were used. In experiment 1, the pH optima over a pH range 4.0-6.8 and the stability of D and L under changing pH (4.0, 5.6, 6.8) and temperature (15 and 39 degreesC) conditions were determined. In experiment 2, D and L were applied at three levels to whole crop maize at ensiling, using triplicate 0.5 kg capacity laboratory minisilos. A completely randomized design with a factorial arrangement of treatments was used. One set of treatments was stored at room temperature, whereas another set was stored at 40 degreesC during the first 3 weeks of fermentation, and then stored at room temperature. Silages were opened after 120 days. Results from experiment I indicated that the xylanase activity of both products showed an optimal pH of about 5.6, but the response differed according to the enzyme, whereas the endoglucanase activity was inversely related to pH. Both products retained at least 70% of their xylanase activity after 48 h incubation at 15 or 39 degreesC. In experiment 2, enzymes reduced (P < 0.05) silage pH, regardless of storage temperature and enzyme level. Depol 40 reduced (P < 0.05) the starch contents of the silages, due to its high alpha-amylase activity. This effect was more noticeable in the silages stored at room temperature. Addition of L reduced (P < 0.05) neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents. In vitro rumen degradation, assessed using the Reading Pressure Technique (RPT), showed that L increased (P < 0.05) the initial 6 h gas production (GP) and organic matter degradability (OMD), but did not affect (P > 0.05) the final extent of OMD, indicating that this preparation acted on the rumen degradable material. In contrast, silages treated with D had reduced (P < 0.05) rates of gas production and OMD. These enzymes, regardless of ensiling temperature, can be effective in improving the nutritive quality of maize silage when applied at ensiling. However, the biochemical properties of enzymes (i.e., enzymic activities, optimum pH) may have a crucial role in dictating the nature of the responses. (C) 2003 Elsevier B.V. All rights reserved.

Multitrophic effects of nutrient addition in upland grassland

Although the effects of nutrient enhancement on aquatic systems are well documented, the consequences of nutritional supplements on soil food webs are poorly understood, and results of past research examining bottom-up effects are often conflicting. In addition, many studies have failed to separate the effects of nutrient enrichment and the physical effects of adding organic matter. In this field study, we hypothesised that the addition of nitrogen to soil would result in a trophic cascade, through detritivores (Collembola) to predators (spiders), increasing invertebrate numbers and diversity. Nitrogen and lime were added to plots in an upland grassland in a randomised block design. Populations of Collembola and spiders were sampled by means of pitfall traps and identified to species. Seventeen species of Collembola were identified from the nitrogen plus lime (N + L) and control plots. Species assemblage, diversity, richness, evenness and total number were not affected by nutrient additions. However, there was an increase in the number of Isotomidae juveniles and Parisotoma anglicana trapped in the N + L plots. Of the 44 spider species identified, over 80% were Linyphiidae. An effect on species assemblage from the addition of N + L to the plots was observed on two of the four sampling dates (July 2002 and June 2003). The linyphiid, Oedothorax retusus, was the only species significantly affected by the treatments and was more likely to be trapped in the control plots. The increased number of juvenile Collembola, and change in community composition of spiders, were consequences of the bottom-up effect caused by nutrient inputs. However, despite efforts to eliminate the indirect effects of nutrient inputs, a reduction in soil moisture in the N + L plots cannot be eliminated as a cause of the invertebrate population changes observed. Even so, this experiment was not confounded by the physical effects of habitat structure reported in most previous studies. It provides evidence of moderate bottom-up influences of epigeic soil invertebrate food webs and distinguishes between nutrient addition and plant physical structure effects. It also emphasises the importance Of understanding the effects of soil management practices on soil biodiversity, which is under increasing pressure from land development and food production.