This paper empirically examines the hypothesis that popularity is typified by ‘electoral cycle effects’. We suggest that if the data is filtered, on the basis of a model assuming informed voters, there is no evidence for the electoral cycle hypothesis.
Options for the storage and disposal of animal carcasses are extremely limited in the EU after the introduction of the EU Animal By-products Regulations (ABPR; EC/1774/2002), leading to animosity within the livestock sector and the call for alternative methods to be validated. Novel storage technologies such as bioreduction may be approved under the ABPR provided that they can be shown to prevent pathogen proliferation. We studied the survival of Enterococcus faecalis, Salmonella spp., E. coli O157 and porcine parvovirus in bioreduction vessels containing sheep carcasses for approximately 4 months. The vessels were operated under two different scenarios: (A) where the water within was aerated and heated to 40 °C, and (B) with no aeration or heating, to simulate vessel failure. Microbial analysis verified that pathogens were contained within the bioreduction vessel and indeed reduced in numbers with time under both scenarios. This study shows that bioreduction can provide an effective and safe on-farm storage system for livestock carcasses prior to ultimate disposal. The findings support a review of the current regulatory framework so that bioreduction is considered for approval for industry use within the EU.
The biological fixation of atmospheric nitrogen (N) is a major pathway for available N entering ecosystems. In N-limited boreal forests, a significant amount of N2 is fixed by cyanobacteria living in association with mosses, contributing up to 50 % to the total N input. In this review, we synthesize reports on the drivers of N2 fixation in feather moss-cyanobacteria associations to gain a deeper understanding of their role for ecosystem-N-cycling. Nitrogen fixation in moss-cyanobacteria associations is inhibited by N inputs and therefore, significant fixation occurs only in low N-deposition areas. While it has been shown that artificial N additions in the laboratory as well as in the field inhibit N2 fixation in moss-cyanobacteria associations, the type, as well as the amounts of N that enters the system, affect N2 fixation differently. Another major driver of N2 fixation is the moisture status of the cyanobacteria-hosting moss, wherein moist conditions promote N2 fixation. Mosses experience large fluctuations in their hydrological status, undergoing significant natural drying and rewetting cycles over the course of only a few hours, especially in summer, which likely compromises the N input to the system via N2 fixation. Perhaps the most central question, however, that remains unanswered is the fate of the fixed N2 in mosses. The cyanobacteria are likely to leak N, but whether this N is transferred to the soil and if so, at which rates and timescales, is unknown. Despite our increasing understanding of the drivers of N2 fixation, the role moss-cyanobacteria associations play in ecosystem-N-cycling remains unresolved. Further, the relationship mosses and cyanobacteria share is unknown to date and warrants further investigation.
Ruminant urine nitrogen (N) concentration and volume are important parameters influencing the size and N loading rate of urine patches deposited to soil. Such parameters can influence N cycling and emissions of the greenhouse gas, nitrous oxide (N2O) from grazed grassland, yet, there is limited information on the effect of these parameters within typical ranges reported for sheep. We used an automated, high-frequency gas monitoring system to investigate N2O emissions from varying urine N application rates and patch sizes under field conditions. Using artificial sheep urine, we manipulated urine N concentration to provide two urine N application rates (4 and 16 g N/L; equivalent to 200 and 800 kg N/ha). We investigated the effect of urine patch size with equal N application rates (4 × 125 cm2 vs 500 cm2, at 200 and 800 kg N/ha) and the effect of patch size with unequal N application rates, but the same total amount of N applied (62.5 mL over 125 cm2 at 800 kg N/ha and 250 mL over 500 cm2 at 200 kg N/ha). Cumulative emissions of N2O generally increased with N loading rate, whether applied as one large urine patch or four smaller ones. Cumulative N2O emissions increased when the N was applied in four smaller urine patches compared with one large patch; this difference was significant at 800 kg N/ha, but not at 200 kg N/ha. When the total amount of N applied was held constant (1 g of N), the amount of N2O released was similar when urine was applied as a high N concentration small patch (800 kg N/ha) compared with a low N concentration large patch (200 kg N/ha). Urine N2O emission factors in this study were, on average, 10 times lower than the IPCC default of 1% for sheep excreta. This research clearly demonstrates that the chemical and physical nature of the urine patch influences N2O emissions, yet further research is required to gather more data on typical sheep urine volumes (individual and daily), urination frequency, urine N concentrations and the typical volumes of soil influenced by urine deposition, to provide more accurate estimates of emissions from sheep grazed pastures.
Cross-sectional survey results from a COVID19 plane infection risk survey conducted between the 22<sup>nd</sup> to 23<sup>rd</sup> October, 2020. Participants (<em>n</em> = 2103) were aged 18 years or older, were living in the UK and had undertaken foreign air travel. The survey consisted of 18 closed-ended questions, with seventeen of the questions addressing issues associated with travelling by air and 11 questions addressing specific demographic topics. The questionnaire was designed by the research team, consisting of environmental microbiologists, public health specialists and social scientists, based on the study objectives and incorporating information from previous studies on same topic. The draft questionnaire was then tested on an expert panel, a panel of non-experts, a local ethics committee. First, perceived risks, concerns, and subjective knowledge of COVID-19 symptoms were measured using 16 options that included 14 actual symptoms and 2 which were not. Other questions about perception and risk were measured by statements with a 5-point Likert scale (e.g. strongly disagree to strongly agree).
The bulk density, total porosity, air porosity and water-holding capacity of mixtures of equal parts of either sand or scoria with peat moss, pinebark, poppy straw and sawdust can be predicted from the respective properties of the ingredients. Total porosity of the media was inversely correlated to bulk density, but there is no clear correlation between air porosity and bulk density. Air porosity increased with pot size.
Macrozamia johnsonii
This Special Issue presents a collection of papers commissioned to celebrate the UK Centre for Doctoral Training (CDT) in soil science known as 'STARS' (Soils Training And Research Studentships). The collection was written by emerging scientists and their collaborating supervisory teams. The call for papers was principally aimed at STARS students, but submissions were also encouraged from students in the wider UK soils community, who are also represented. The STARS CDT was originally commissioned in 2015 as part of a funding collaboration between the UK Natural Environment Research Council and the UK Biotechnology and Biological Science Research Council (BBSRC). The paper by Haygarth et al. (2021) provides a reflection on the STARS CDT experience, exploring what can be learnt from the new pedagogic approach. It describes how a discipline-focussed doctoral centre is a novel and unique way of teaching and learning soil science, proposing that this might be a model for future post graduate soil science teachers to learn from, in order to continually improve and innovate in the way we train our PhD students. In total, the Special Issue contains 17 papers, of which 15 appear in hard copy (incidentally, the last hard copy issue of the European Journal of Soil Science before conversion to solely on-line publication). All but one of the papers (Haygarth et al., 2021) are student-led, with three by non-STARS students (Jonah Prout, Yan Ma and Melanie Armbruster). The papers loosely fall into three categories: (1) Those involving local-scale controlled experiments and method development (seven papers), (2) those focussed on empirical analyses of large-scale datasets (six papers) and (3) those that involve a meta-analyses of previously published literature (three papers). In the first category, Chris McCloskey contributes two papers as lead author. In the first paper (McCloskey et al., 2020), a field system is presented for measuring plant and soil carbon fluxes using stable isotope methods, with sufficient precision to resolve diurnal and seasonal patterns. In the companion paper, the field system is used to demonstrate the importance of allowing for transient variation in plant and soil δ13C end members in partitioning fluxes from net ecosystem respiration (McCloskey et al., 2021). Ma et al. (2021) assessed the relative efficacy of nitrification inhibitors in a highly nitrifying soil and, like McCloskey, used carbon-labelling techniques to help achieve this. Dan Evans takes us to the core of soil formation, using a new technique of cosmogenic radionuclide analysis (Evans et al., 2021) with a conclusion that questions the accuracy of our existing soil formation knowledge, arguing that we must consider the bulk density profile of the overlying soil. At a slightly larger scale, 'Bee' Burak et al. (2020) uses an inductive mesocosm-based assessment to study how root hairs affect soil erosion by simulated rainfall. In similar controlled conditions, Corina Lees et al. (2020) used a growth room to control her climate change study in selecting plant traits for soil erosion control in grassed waterways. Marta Cattin et al. (2021) also uses controlled conditions with a 21-day laboratory microcosm incubation in order to assess the fate of soil carbon following the application of anaerobic digestate. In the second category, Fiona Seaton et al. (2020) uses an empirical data-driven analysis based on national (Welsh) monitoring of soil indicators to reflect on soil health, using large-scale data analyses (over 1350 topsoils) to understand the state and change of soils at a national scale. Her work shows the importance of land-use management in determining the soil health and functional capacity of soils. In an empirical approach not dissimilar, Armbruster et al. (2020) has a focus on bacterial and archaeal taxa as potential indicators of soil restoration across grasslands. The work highlights that microbial taxon are among the most sensitive indicators of soil restoration. Paul George et al. (2020) studied anaerobes and sulphate-reducing bacteria in relation to pH across varied land uses, using a nationwide 'metabarcoding' dataset from 436 sites belonging to seven contrasting temperate land uses. Andrew Tweedie et al. (2021) tested the hypothesis that phosphorus forms and functions in agricultural soils have changed over a period of 50–70 years, using topsoils from 35 agricultural sites in Northeast Scotland, compared at 'original' and 'resampled' timepoints. The paper by Hannah Cooper (2021) uses a broadly similar 'long-term' sampling approach and considers how long-term zero-tillage enhances the protection of soil carbon in tropical agriculture, studying soil samples collected from experimental fields in Botucatu, Brazil, which had been under zero-tillage for 2, 15 and 31 years. The paper by Prout et al. (2020) focusses on soil organic matter and proposes an index approach based on organic carbon-to-clay ratio. Again, like the above papers this work was empirically based, using 3809 sites from the National Soil Inventory of England and Wales. In the third category, Harry Barrat studied the impact of drought and rewetting on nitrous oxide emissions from soil in temperate and Mediterranean climates (Barrat et al., 2020). The method used the first meta-analysis and synthesis of the literature. Anchen Kehler et al. (2021) also applied a literature-based approach to her work, trying to predict how soil phosphorus will react to climate change. Finally in a wonderful collaborative article between the STARS students, Mihai Cimpoiasu et al. (2021) was first author on a reflective consideration of future priorities for soil science: 'Comparing perspectives from scientists and stakeholders'. Soil science has never seemed so topical, providing services underpinning our existence (Haygarth & Ritz, 2009) while addressing sustainable development and global grand challenges (Lal et al., 2021). It is thus timely to see this collection led by early career scientists on Innovations in Soil Science to Address Global Grand Challenges. Moreover, it is encouraging, not only because of the diversity of research findings themselves, but because of the promise it shows for our future capacity to deliver the discipline. Data sharing is not applicable to this article as no new data were created or analyzed in this study.
Background Monitoring the properties of dissolved organic carbon (DOC) in soil water is frequently used to evaluate changes in soil quality and to explain shifts in freshwater ecosystem functioning. Methods Using >700 individual soils (0–15 cm) collected from a 209,331 km2 area we evaluated the relationship between soil classification (7 major soil types) or vegetation cover (8 dominant classes, e.g. cropland, grassland, forest) and the absorbance properties (254 and 400 nm), DOC quantity and quality (SUVA, total soluble phenolics) of soil water. Results Overall, a good correlation (r2 = 0.58) was apparent between soil water absorbance and DOC concentration across the diverse range of soil types tested. In contrast, both DOC and the absorbance properties of soil water provided a poor predictor of SUVA or soluble phenolics which we used as a measure of humic substance concentration. Significant overlap in the measured ranges for UV absorbance, DOC, phenolic content and especially SUVA of soil water were apparent between the 8 vegetation and 7 soil classes. A number of significant differences, however, were apparent within these populations with total soluble phenolics giving the greatest statistical separation between both soil and vegetation groups. Conclusions We conclude that the quality of DOC rather than its quantity provides a more useful measure of soil quality in large scale surveys.
The rhizosphere is the zone of soil immediately surrounding plant roots that is modified by root activity. In this critical zone, plants perceive and respond to their environment. As a consequence of normal growth and development, a large range of organic and inorganic substances are exchanged between the root and soil, which inevitably leads to changes in the biochemical and physical properties of the rhizosphere. Plants also modify their rhizosphere in response to certain environmental signals and stresses. Organic anions are commonly detected in this region, and their exudation from plant roots has now been associated with nutrient deficiencies and inorganic ion stresses. This review summarizes recent developments in the understanding of the function, mechanism, and regulation of organic anion exudation from roots. The benefits that plants derive from the presence of organic anions in the rhizosphere are described and the potential for biotechnology to increase organic anion exudation is highlighted.
