Global nitrogen fertilizer supply and demand outlook

This paper presents a brief overview of the world nitrogen fertilizer demand, highlights trends in the global and regional developments of production capacity and provides a medium-term perspective of the global nitrogen supply/demand balance.     

Can mineralization of soil organic nitrogen meet maize nitrogen demand?

Background and aims

It is generally assumed that very large herbivores, such as elephants, make foraging decisions at large spatial scales, but the extent to which seasonal foraging decisions are driven by soil quality, and its link to plant nutrient levels, is uncertain.

Methods

We studied the diet selection of African elephants Loxodonta africana in Ithala Game Reserve in northern KwaZulu-Natal, South Africa, using data on elephant feeding preferences and spatial distributions from a published paper. Elephants were present in the eastern half with granite soils in the wet season, and in the western half with sedimentary soils in the dry season. The quality of these two soil types and of seven key tree species for elephants was assessed in both seasons.

Results

Soil quality was higher on the sedimentary soils in terms of total nitrogen, soil respiration, water-holding capacity, organic carbon and pH. Leaf quality was higher on the sedimentary soils in the dry season, while in the wet season there was no significant difference in leaf quality of the seven key tree species growing on the two substrates.

Conclusion

Soil quality may explain elephants’ foraging decisions in the dry season, but not in the wet season. Elephants preferred trees with higher protein and lower concentrations of fibre on both granite and sedimentary soils.

     

Can China's supply of scientific talent keep up with demand?

Opportunities for scientists abound as China sets its sights on joining the global biotech sector.     

Nocturnal energy demand in plants: Insights from studying mutants impaired in β-oxidation

All photosynthetic organisms face the difficulty of maintaining cellular metabolism in the absence of photosynthetic active radiation during the night. Although many consuming metabolic pathways (e.g., fatty acid synthesis) are only active in the light, plant cells still require basic levels of metabolic energy and reductive power during the night for sustained growth and development.Key words: PXA1, comatose, β-oxidation, fatty acids, starch, imaging PAM, extended darkness     

Bioremediation of synthetic high–chemical oxygen demand wastewater using microalgal species Chlorella pyrenoidosa

The microalgal species Chlorella pyrenoidosa was cultivated in synthetic wastewater of initial chemical oxygen demand (COD), nitrate, and phosphate concentrations of 5000, 100, and 40 mg/L, respectively. The aim of the study was to find out the tolerance of microalgae to different COD concentrations and the extent of COD degradation at those concentrations. Three dilutions of wastewater (initial COD concentrations 5000, 3000, and 1000 mg/L) and three inoculum sizes (0.1, 0.2, and 0.3 g/L) were considered for the study. The experimental parameters such as total organic carbon, total inorganic carbon, COD, optical density, total solids, nitrate, and phosphate were measured on a daily basis. Biodegradation kinetics was determined for all cases using first-order reaction and Monod degradation equations. Optimal results showed that up to 90% reduction in TOC was obtained for 1000 COD wastewater while only 38% reduction in total organic carbon (TOC) was achieved for 5000 COD wastewater. Over 95% reduction in nitrate and nearly 90% removal of phosphate were obtained with the lowest microalgal inoculum concentration (i.e., 0.1 g/L) for all COD dilutions. This study showed that microalgal species C. pyrenoidosa can successfully degrade the organic carbon source (i.e., acetate) with significant removal efficiencies for nitrate and phosphate.     

Can current native tree seedling production and infrastructure meet an increasing forest restoration demand in Brazil?

Recent global commitments have placed forest and landscape restoration at the forefront of countries' efforts to recover ecosystem services, conserve biodiversity, and mitigate the effects of climate change. However, it needs to be asked if current native tree seedling supply meets an increase in demand for forest restoration? This study assessed the current configuration, distribution, and production capacity of forest nurseries producing native trees in Brazil. Brazil provides an interesting example of how global agreements aligned with national policies can lead to the proliferation of native seedling nurseries, and the challenges faced to restore species‐rich native forest ecosystems. We found that the nurseries in the Atlantic Forest region can still meet an increase in demand—both in terms of seedling quantity and diversity—because most of their production capacity is not currently used. However, not all Brazilian biomes have sufficient nurseries to meet restoration demands, thus there is a risk of using native species from a few biogeographical regions in a much spatially wider and ecologically diverse area. In addition, lack of seed supply and qualified labor can hamper the growth of the market. Barriers to seed supply may also lead to low levels of genetic variability and floristic representation in the populations and ecosystems to be restored. We conclude that restoration of high‐diversity forest ecosystems requires policies and supportive programs, with emphasis on private nurseries, to guarantee adequate supply of native tree seedlings and provide the necessary incentives to develop the emergent economy of forest restoration.     

Functional unit and product functionality—addressing increase in consumption and demand for functionality in sustainability assessment with LCA

Purpose

The static functional unit definition in the current LCA framework has limitations in addressing the changing product functionality and associated environmental impact of constantly evolving product technologies. As a result, it overlooks the changes in consumer behaviour of increased consumption of products in provided services as well as in growing volumes. This article aims to present a new framework in defining a dynamic functional unit of product technologies that caters for changes in consumer behaviour and growing market.

Methods

A new approach to defining the functional unit is proposed that caters for changes in consumer behaviour and the use of technology from a technical performance perspective. A dynamic approach to definition of the functional unit is proposed that is based on Kano’s model of product function and satisfaction.

Results and discussion

The new approach is demonstrated on a case study in which the analysis of historical data for two TV product technologies—CRT and LCD—is used to show how the total environmental impact is increasing due to the increased functionality which triggers an increase in the volume of the market. Despite the efforts of improving product life cycle design, the society is still faced with increasing environmental impact from the product type overall.

Conclusions

This article presents the challenges of using a static, single functional unit definition in an industrial culture with constant evolution of products that influences usage behaviour and demonstrates the vicious circle of improving product efficiency that leads to further consumption and environmental impact. To address this problem, a new framework of dynamic functional unit definition is put forward for performing comparative LCA to manage the development of product life cycle design that helps keep the total environmental impact of the company’s product portfolio within absolute boundaries.

     

Stay‐green: A consequence of the balance between supply and demand for nitrogen during grain filling?

Retention of green leaf area in grain sorghum under post‐anthesis drought, known as stay‐green, is associated with greater biomass production, lodging resistance and yield. The stay‐green phenomenon can be examined at a cell, leaf, or whole plant level. At a cell level, the retention of chloroplast proteins such as LHCP2, OEC33 and Rubisco until late in senescence has been reported in sorghum containing the KS19 source of stay‐green, indicating that photosynthesis may be maintained for longer during senescence in these genotypes. At a leaf level, longevity of photosynthetic apparatus is intimately related to nitrogen (N) status. At a whole plant level, stay‐green can be viewed as a consequence of the balance between N demand by the grain and N supply during grain filling. To examine some of these concepts, nine hybrids varying in the B35 and KS19 sources of stay‐green were grown under a post‐anthesis water deficit. Genotypic variation in delayed onset and reduced rate of leaf senescence were explained by differences in specific leaf nitrogen (SLN) and N uptake during grain filling. Matching N supply from age‐related senescence and N uptake during grain filling with grain N demand found that the shortfall in N supply for grain filling was greater in the senescent than stay‐green hybrids, resulting in more accelerated leaf senescence in the former. We hypothesise that increased N uptake by stay‐green hybrids is a result of greater biomass accumulation during grain filling in response to increased sink demand (higher grain numbers) which, in turn, is the result of increased radiation use efficiency and transpiration efficiency due to higher SLN. Delayed leaf senescence resulting from higher SLN should, in turn, allow more carbon and nitrogen to be allocated to the roots of stay‐green hybrids during grain filling, thereby maintaining a greater capacity to extract N from the soil compared with senescent hybrids.     

Regulation of food provisioning and parental body condition in Leach’s storm-petrels, Oceanodroma leucorhoa: Experimental manipulation of offspring food demand

We examined the effects of offspring food demand on parental regulation of food provisioning and body condition in a small long-lived seabird, Leachs storm-petrels (Oceanodroma leucorhoa). In one experimental group, food demand of chicks on their parents was increased by removing one parent (single), and in another group these food demands were decreased by supplementary feeding of chicks (supplement). A further unmanipulated group provided a control. Feeding frequencies by one parent were higher in the single but lower in the supplement than in the control group, in accordance with the food demand of chicks. The size of meals appeared to be not different among the experimental groups. However, as single parents did not compensate perfectly for the increase of chick food demand by food provisioning, single chicks grew at slower rates and fledged at smaller masses than control chicks. Supplement chicks grew at similar rates and fledged at similar masses as control chicks, because parents decreased food provisioning and food processing capacity of the chicks might be limited. The body condition of parents, which was determined by body mass loss and feather regrowth rate, did not differ among the groups. These results indicate that feeding frequency was regulated by parental decision in this storm-petrel species. Parents may adjust their food provisioning to match the food demand of chicks but within a certain range so as not to deteriorate their own body condition.     

Consumer demand for caesarean sections in Brazil: informed decision making,patient choice,or social inequality? A population based birth cohort study linking ethnographic and epidemiological methods

ObjectivesTo investigate why some women prefer caesarean sections and how decisions to medicalise birthing are influenced by patients, doctors, and the sociomedical environment.DesignPopulation based birth cohort study, using ethnographic and epidemiological methods.SettingEpidemiological study: women living in the urban area of Pelotas, Brazil who gave birth in hospital during the study. Ethnographic study: subsample of 80 women selected at random from the birth cohort. Nineteen medical staff were interviewed.Participants5304 women who gave birth in any of the city''s hospitals in 1993.ResultsIn both samples women from families with higher incomes and higher levels of education had caesarean sections more often than other women. Many lower to middle class women sought caesarean sections to avoid what they considered poor quality care and medical neglect, resulting from social prejudice. These women used medicalised prenatal and birthing health care to increase their chance of acquiring a caesarean section, particularly if they had social power in the home. Both social power and women''s behaviour towards seeking medicalised health care remained significantly associated with type of birth after controlling for family income and maternal education.ConclusionsFear of substandard care is behind many poor women''s preferences for a caesarean section. Variables pertaining to women''s role in the process of redefining and negotiating medical risks were much stronger correlates of caesarean section rates than income or education. The unequal distribution of medical technology has altered concepts of good and normal birthing. Arguments supporting interventionist birthing for all on the basis of equal access to health care must be reviewed.

What is already known on this topic

Women''s preferences for caesarean sections are understood to result from lack of knowledge and psychological aptitude to handle vaginal delivery and its consequencesEfforts to reduce the demand for caesarean sections have focused on providing consumers with correct information on the relative risks associated with vaginal and operative deliveries

What this study adds

In Brazil, many women prefer caesarean sections because they consider it good quality careRich women are more likely to have caesarean sections, supporting the notion that medical intervention represents superior carePoor women may implement a series of medicalised practices that justifies the need for greater medical intervention during birthInterventions for reducing caesarean sections by educating physicians and patients about risk factors associated with birthing procedures are not sufficient     

Catechol-oxide-methyltransferase (<Emphasis Type="Italic">COMT</Emphasis> rs4680:G&gt;A) gene polymorphism does not affect analgesics’ demand after elective hip replacement

Pain in patients with hip osteoarthritis appears long before surgery, and requires effective management as it affects patient comfort and daily activities. Therefore, the search for factors influencing response rate to analgesics is mandatory. In recent years, increasing attention has been paid to genetic factors underlying pain threshold and treatment efficacy. Polymorphic gene of catechol-oxide-methyltransferase (COMT) is a candidate gene associated with pain pathology and treatment response. The aim of the study was to evaluate association between the COMT rs4680:G>A polymorphism and demand for analgesics in patients subjected to elective hip replacement. The study included 196 patients after hip replacement surgery. Opioid demand was recorded and analgesic efficacy was scored using a four-level verbal pain intensity scale. COMT rs4680:G>A polymorphism was analysed by PCR-RFLP method. The studied COMT genotypes did not influence opioid administration in the studied patients from the day of surgery till day 6 afterwards. The distribution of the COMT rs4680:G>A in the studied subjects was as follows: GA—52.04%, AA—23.98% and GG—23.98%. It can be concluded that the COMT rs4680:G>A polymorphism is not associated with opioid demand in patients after elective hip replacement.     

Does the accelerated soil N cycling sustain N demand of <Emphasis Type="Italic">Quercus mongolica</Emphasis> after decade-long elevated CO<Subscript>2</Subscript> treatment?

Net methane (CH₄) flux across the ecosystem-atmosphere boundary is governed by two counteracting processes, CH₄ oxidation and production. Recent research on CH₄ cycling has focused on net CH₄ fluxes, however, the separate processes of CH₄ oxidation and production may vary at local scales and respond differently to environmental change. Here, we separate CH₄ oxidation and production, measured as emission, in situ using CH₄ oxidation inhibition combined with a novel in situ ¹³CH₄ labeling experiment to determine the rate of soil oxidation of atmospheric CH₄. The study was conducted in a subarctic heath ecosystem with three characteristic plant community types: moist mixed species heath, dry Carex-dominated heath, and wet Eriophorum-dominated fen. We further explored the projected climate change effects of increased temperature and enhanced leaf litter input. The CH₄ oxidation inhibition experiment revealed significant potential CH₄ emission despite net CH₄ uptake. Total CH₄ oxidation and potential CH₄ emission rates differed significantly between plant communities, demonstrating high local-scale variation in CH₄ fluxes. Climate treatments did not affect CH₄ oxidation rates, however, warming tended to increase potential CH₄ emission, indicating that climate change may affect oxidation and production rates asymmetrically. Near-surface soil oxidation of atmospheric CH₄ was successfully traced using ¹³C stable isotope labeling in situ. CH₄ oxidation rates ranged widely, yet preliminarily suggested some degree of substrate limitation. Accounting for the local-scale variation in CH₄ fluxes and the relative importance of the separate processes of CH₄ oxidation and production will contribute importantly to predicting changes in landscape-scale CH₄ budgets and climate feedbacks.