Publications

This communication reports the deposit ofStreptomyces No. 6 in the National Collection of Industrial Bacteria, Aberdeen, AB2 1RY, Scotland, UK (Accession n

<title>Abstract</title> Plastic film mulch (PFM) controls weeds and increases yields, making them attractive to vegetable growers; biodegradable PFMs potentially reduce the harms associated with conventional PFMs. PFMs increase soil biological activity, accelerating the decomposition of soil organic matter and potentially increasing emissions of some greenhouse gases (GHGs). Conversely, they are a barrier to rainfall infiltration and gas exchange, reducing harmful nitrate (NO₃⁻) leaching and ammonia (NH₃) volatilisation. The effects of PFMs on the processes resulting in GHG emissions are not well explored outside conventionally grown commodity crops in major growing regions. To address this, we conducted a field plot-scale experiment on an organic vegetable farm in SW Wales (UK). We measured nitrous oxide (N₂O), methane (CH₄), carbon dioxide (CO₂) and potential NH₃ emission from the soil, growing leeks or cabbages, with or without biodegradable PFM and amended with poultry manure or green-waste compost. Averaged across both crops, yield was 26% higher with PFM; potential NH₃ emissions were 18% lower (43% on a yield-scaled basis) in mulched treatments than unmulched; CH₄ emissions were not significantly affected. Yield-scaled N₂O emissions were 62% higher in mulched leeks than unmulched but 56% lower in mulched cabbages than unmulched; this coincided with higher soil NO₃⁻ concentrations in mulched leeks than either unmulched crop or mulched cabbages. Results were not obtained for CO₂, so partial global warming potential (GWP) and greenhouse gas intensity (GHGI) were determined mainly by N₂O emissions. Thus, biodegradable PFM is potentially useful in reducing harmful gaseous N emissions in organic horticulture.

In comparison to traditional windrow composting, in-vessel composting techniques often represent more effective waste management options due to the reduced production of bioaerosols and leachate and the potential for better process control. Chemical processes occurring during the cocomposting of three common wastes (green waste, biosolids and paper processing waste) were studied using the forced aeration, static pile, in-vessel EcoPOD® composting system. Since no turning of the compost occurs within the static piles, spatial differences in the vessel were also monitored. These measurements revealed significant spatial gradients in temperature; however, this did not result in spatial differences in nutrients within the composting vessel. Significant differences in soluble N production were observed during the composting process following the series: green plus paper waste < green waste < green waste plus biosolids. After the active compost phase was over, and the compost was removed from the vessel and matured outside, we demonstrated that covering the compost was essential to preserve compost quality. Our study clearly shows that cocomposting of common waste feedstocks can be used to successfully manipulate the chemistry of the final compost making it suitable for multiple end uses. In addition, our study demonstrated that careful management of the compost maturing phase is also required to maximise quality and minimize pollution.

An investigation has been made of synthesis conditions leading to water-swelling lithium fluorhectorites. Other phases which appeared, the yields of which had to be minimised, were α-quartz, lithium metasilicate, and fluoramphibole. When made by sintering reactions at 800° the fluorhectorites had exchange capacities of ca. 90 mequiv. per 100 g.; if prepared at 850° with lithium fluoride melts as flux this capacity was ca. 150 mequiv. per 100 g. The water-swelling phases did not lose their ability to swell even after heating to 800°; at higher temperatures there was significant defluorination of the structure.Na-, K-, Rb-, Cs-, Ca-, Sr-, and Ba-exchanged forms were prepared from the Li-fluorhectorites, and water isotherms, and swelling were measured on all forms. K-, Rb-, and Cs-modifications were essentially anhydrous; the other forms intercalated water in successive layers, the isotherms showing steps for the first and second layers. Third layers were observed only from the X-ray basal spacings of the wetted water-swelling forms. One- and two-layer complexes gave rational higher orders of the basal X-ray reflections, but not the three-layer complexes. One- and two-layer complexes corresponded with 4 or 8 water molecules per unit cell.Swelling of the exchanged forms in glycol also occurred to give two layer complexes with Li-, Na-, Ca-, Sr-, and Ba- but not with K-, Rb-, and Cs-exchanged forms. Very clear higher orders of the basal reflection were obtained.

No abstract is provided for this article.

The psychometric paradigm has dominated the field of empirical work analysing risk perceptions. In this paper, we use an alternative method, Best-Worst Scaling (BWS), to elicit relative risk perceptions concerning potentially unsafe domestic food behaviours. We analyse heterogeneity in those risk perceptions via estimation of latent class models. We identify 6 latent segments of differing risk perception profiles with the probability of membership of those segments differing between experts and the lay public. The BWS method provides a practical approach to assessing relative risks as the choices made by the participants and subsequent analysis have a strong theoretical basis. It does so without the influence of scale bias, the cognitive burden of ranking a large number of items or issues of aggregation of data, often associated with the more commonly used psychometric paradigm. We contend that BWS, in conjunction with latent class modelling, provides a powerful method for eliciting risk rankings and identifying differences in these rankings in the population.

The hydrological transport of low-molecular weight organic nitrogen (LMWON) compounds has received little attention in the literature, particularly relative to inorganic nitrogen (N), with less attention given to the decoupling of the carbon (C) and N cycles following rainfall events. We determined the impacts of the soil biota on the transport of N compounds in a loam soil, using 15N and 13C to trace the vertical transport of 15N13C-urea, 15N13C-amino acids, 15NO3, and 15NH4 through the soil profile, following simulated rainfall events. This research has demonstrated that biotic assimilation leads to rapid decoupling of the C and N cycles during leaching, with C transport limited to the soil surface (< 2 cm), whereas N which was stored within the soil profile during a single rainfall event could be remobilised and leached (a further 2–6 cm) following an additional rainfall event.

Examination of 14 collections of Aecidium on Agathis, including type material of A. balansae Cornu ex Pat. and specimens of A. fragiforme Gesati from the type locality, by optical and electron microscopy indicated two morphologically distinct taxa. These are distinguished primarily by ornamentation of the aeciospore surface. Taxon I (A. balansae) has aeciospores with surface projections each consisting of a stalk and hemispherical head superposed by a conical cap, and Taxon 2 (A. fragiforme) has aeciospores with capitate, distinctly ridged spines.

Earthworm digested wastes (vermicompost) are being produced in increasing quantities and there is much interest in developing new markets for these products. In this paper, the responses of wheat (Triticum aestivum var. Einstein and Xi19) to vermicompost additions and to combinations of vermicompost and inorganic NPK fertilizer in field and glasshouse environments are considered. Plant response was determined by measuring a range of ontogenetic parameters (plant growth, chlorophyll content, fertile ears, tiller number and grain yield). The individual treatments involved the addition of 1, 10 and 30 t ha−1 of vermicompost to soil, or the coapplication of 1, 10 and 30 t ha−1 of vermicompost plus NPK fertilizer where the N addition rate was normalized to 150 kg N ha−1. Photosynthetic pigment development, plant growth, and yield were reduced in all treatments in the absence of inorganic fertilizer. However, all coapplication treatments resulted in similar yields to NPK fertilizer alone in both field and glasshouse experiments. It is our conclusion that vermicompost alone cannot provide a viable substitute for inorganic fertilizer without causing a significant loss of yield; however, it may enhance soil quality if integrated into conventional arable cropping practices which use inorganic fertilizers.

Summary The Green Revolution successfully increased food production but in doing so created a legacy of inherently leaky and unsustainable agricultural systems. Central to this are the problems of excessive nutrient mining. If agriculture is to balance the needs of food security with the delivery of other ecosystem services, then current rates of soil nutrient stripping must be reduced and the use of synthetic fertilisers made more efficient. We explore the global extent of the problem, with specific emphasis on the failure of macronutrient management (e.g. nitrogen, phosphorus) to deliver continued improvements in yield and the failure of agriculture to recognise the seriousness of micronutrient depletion (e.g. copper, zinc, selenium). Nutrient removals associated with the relatively immature, nutrient‐rich soils of the UK are contrasted with the mature, nutrient‐poor soils of India gaining insight into the emerging issue of nutrient stripping and the long‐term implications for human health and soil quality. Whilst nutrient deficiencies are rare in developed countries, micronutrient deficiencies are commonly increasing in less‐developed countries. Increasing rates of micronutrient depletion are being inadvertently accomplished through increasing crop yield potential and nitrogen fertiliser applications. Amongst other factors, the spatial disconnects caused by the segregation and industrialisation of livestock systems, between rural areas (where food is produced) and urban areas (where food is consumed and human waste treated) are identified as a major constraint to sustainable nutrient recycling. Synthesis and applications . This study advocates that agricultural sustainability can only be accomplished using a whole‐systems approach that thoroughly considers nutrient stocks, removals, exports and recycling. Society needs to socially and environmentally re‐engineer agricultural systems at all scales. It is suggested that this will be best realised by national‐scale initiatives. Failure to do so will lead to an inevitable and rapid decline in the delivery of provisioning services within agricultural systems.

Amino sugars can be used as indices to evaluate the role of soil microorganisms in active nitrogen (N) cycling in soil. This paper details the assessment of the suitability of gas chromatography–combustion–isotope ratio mass spectrometry (GC–C–IRMS) for the analysis of 15N-enriched amino sugars as alditol acetate derivatives prior to application of a novel 15N stable isotope probing (SIP) approach to amino sugars. The efficient derivatization and cleanup of alditol acetate derivatives for GC was achieved using commercially available amino sugars, including glucosamine, mannosamine, galactosamine, and muramic acid, as laboratory standards. A VF-23ms stationary phase was found to produce optimal separations of all four compounds. The structure of the alditol acetate derivatives was confirmed using gas chromatography/mass spectrometry (GC/MS). For GC–C–IRMS determinations, implementation of a two-point normalization confirmed the optimal carrier gas flow rate to be 1.7 mL min–1. Linearity of δ15N value determinations up to δ15Nt of 469 ± 3.1‰ (where δ15Nt is the independently measured δ15N value) was confirmed when 30 nmol N was injected on-column, with the direction of deviation from δ15Nt at low sample amount dependent on the 15N abundance of the analyte. Observed between- and within-run memory effects were significant (P < 0.007) when a highly enriched standard (469 ± 3.1‰) was run; therefore, analytical run order and variation in 15N enrichment of analytes within the same sample must be considered. The investigated parameters have confirmed the isotopic robustness of alditol acetate derivatives of amino sugars for the GC–C–IRMS analysis of 15N-enriched amino sugars in terms of linearity over an enrichment range (natural abundance to 469 ± 3.1‰) with on-column analyte amount over 30 nmol N.