Clover:cereal bi-cropping for organic farms (OF0173)

This is the final report of Defra project OF0173. The attached main report starts with a more detailed summary, from which this text is extracted. IGER, IACR and others developed a system for growing cereals, especially for whole crop silage, that enables either greatly reduced or zero levels of N fertilizer and agrochemicals to be used. The system is simple and straightforward and relies on direct drilling of the cereal into an established understorey of white clover. The white clover understorey becomes permanent and perennial and successive cereal crops are drilled into it, harvested and re-drilled each year. The clover provides N for the cereal crop and the gross changes in crop architecture that occur (a) encourage large populations of predatory invertebrates that devour pest species and hence obviate the need for insecticide use (b) frustrate the spread of fungal foliar diseases and remove the need to use fungicides and (c) suppress most weeds. Some of the advantages of the clover:cereal bi-cropping system that are especially relevant to organic farms are a) simultaneous cropping and fertility building rather than separate seasons for each b) effective nutrient cycling c) weeds replaced by clover; limitation of crop area requiring intensive weed control d) confusion of insect pests and habitat for beneficial insects, spiders etc. e) improved field access relative to bare soil The work investigated the agronomic viability and sustainability of bi-cropping for both silage and grain production in organic farming systems as specified under UKROFS. Experiments were carried out on three UKROF approved sites with contrasting soil types and environmental conditions. Randomised block, small-plot experiments evaluated the most satisfactory ways of modifying the IGER/IACR system for organic farming. The main point to emerge is that although the bi-crop system is well proven and developed for use in a non-organic system, grass weeds remain a problem in translating the system to organic farming as herbicides can not be used to control them. There are a number of strategies that emerged during the course of the present work that indicated ways in which the grass weed problem may be overcome in future. Firstly, oats seem to suppress grass weeds and growing this crop instead of wheat appeared to show considerable promise. Secondly strip drilling alternate 20 cm strips of cereal with 30 cm strips of clover allows separate management of the two crop components, facilitating weed control. The work confirmed that spring-sown cereals are not an option for bi-cropping as they are easily outcompeted by the clover. An important positive feature of all of the trials was the consistent absence or low levels of diseases and pests despite high levels of airborne pathogen inoculum in the trial area. It is difficult to gauge the relative contributions of the organic system as a whole and the bi-crop system in particular to this feature. There are certainly important theoretical reasons as to why the bi-crop system should help in this direction, including the restriction on spread of splash-borne diseases because of the presence of clover around the cereal plants, green background confusion of insect pests and the probable lack of surplus soluble nitrogen in the cereal plants. The more positive results in the absence of grass weeds were limited to a single year for cereals (and two seasons for vegetables in another related trial). However, in both cases, there were clear indications that, with a relatively small amount of fine tuning of the system, it should be possible to obtain highly acceptable results from both types of inter-cropping and, indeed, from rotational integration of the two. Further progress would certainly be worthwhile for the organic producer because it seems clear that a modest further adjustment of the competitive balance between crop and clover will lead to a clearer expression of all of the potential advantages of such systems, outlined above. Despite the difficulties encountered, progress was made and the list of advantages and potential advantages of bi-cropping for organic agriculture is so large and significant that further work should be done to capitalise on that completed to date

Excitations in confined helium

We design models for helium in matrices like aerogel, Vycor or Geltech from a manifestly microscopic point of view. For that purpose, we calculate the dynamic structure function of 4He on Si substrates and between two Si walls as a function of energy, momentum transfer, and the scattering angle. The angle--averaged results are in good agreement with the neutron scattering data; the remaining differences can be attributed to the simplified model used here for the complex pore structure of the materials. A focus of the present work is the detailed identification of coexisting layer modes and bulk--like excitations, and, in the case of thick films, ripplon excitations. Involving essentially two--dimensional motion of atoms, the layer modes are sensitive to the scattering angle.Comment: Phys. Rev. B (2003, in press

Geospatial web services pave new ways for server-based on-demand access and processing of Big Earth Data

Big Earth Data has experienced a considerable increase in volume in recent years due to improved sensing technologies and improvement of numerical-weather prediction models. The traditional geospatial data analysis workflow hinders the use of large volumes of geospatial data due to limited disc space and computing capacity. Geospatial web service technologies bring new opportunities to access large volumes of Big Earth Data via the Internet and to process them at server-side. Four practical examples are presented from the marine, climate, planetary and earth observation science communities to show how the standard interface Web Coverage Service and its processing extension can be integrated into the traditional geospatial data workflow.Web service technologies offer a time- and cost-effective way to access multi-dimensional data in a user-tailored format and allow for rapid application development or time-series extraction. Data transport is minimised and enhanced processing capabilities are offered. More research is required to investigate web service implementations in an operational mode and large data centres have to become more progressive towards the adoption of geo-data standard interfaces. At the same time, data users have to become aware of the advantages of web services and be trained how to benefit from them most

Silvopastoral Agroforestry in Upland and Lowland UK Grassland: Tree Growth and Animal Performance

Trees, individually protected from herbivore damage using plastic shelters, were planted at two densities (100 and 400 stems/ha) into sheepgrazed pasture in upland and lowland UK grassland sites in 1988. Tree and animal performance were compared with conventional forestry (no sheep) and pasture (no tree) systems. Effects on tree growth and survival are highly species and site dependent although some treatment effects did emerge. Tree shelters encouraged rapid early height growth compared to forestry controls although in some cases tree form was also adversely affected. Generally tree performance within agroforestry treatments was better at the higher planting density. Eight years after planting there has been no reduction in animal production despite interception of up to 10% of total photosynthetically active radiation by the developing tree canopy

Quantum sticking, scattering and transmission of 4He atoms from superfluid 4He surfaces

We develop a microscopic theory of the scattering, transmission, and sticking of 4He atoms impinging on a superfluid 4He slab at near normal incidence, and inelastic neutron scattering from the slab. The theory includes coupling between different modes and allows for inelastic processes. We find a number of essential aspects that must be observed in a physically meaningful and reliable theory of atom transmission and scattering; all are connected with multiparticle scattering, particularly the possibility of energy loss. These processes are (a) the coupling to low-lying (surface) excitations (ripplons/third sound) which is manifested in a finite imaginary part of the self energy, and (b) the reduction of the strength of the excitation in the maxon/roton region

Fracture toughness of the cancellous bone of FNF femoral heads in relation to its microarchitecture

This study considers the relationship between microarchitecture and mechanical properties for cancellous bone specimens collected from a cohort of patients who had suffered fractured necks of femur. OP is an acute skeletal condition with huge socioeconomic impact [1] and it is associated with changes in both bone quantity and quality [2], which affect greatly the strength and toughness of the tissue [3].Support was provided by the EPSRC (EP/K020196: Point-ofCare High Accuracy Fracture Risk Prediction), the UK Department of Transport under the BOSCOS (Bone Scanning for Occupant Safety) project, and approved by Gloucester and Cheltenham NHS Trust hospitals under ethical consent (BOSCOS – Mr. Curwen CI REC ref 01/179G)

Creative and productive workplaces: a review

The built environment affects our well-being and this in turn influences our effectiveness in the workplace. Poor environments contribute to absenteeism and to people not working as well as they might. This is an enormous cost to the nation. High-quality environmental design is an investment, as occupants are healthier, staff-retention rates are higher, productivity is higher and sustainability ideals are more likely to be met. Workplaces reflect the culture of companies and are places that are not just functional and convenient but give the occupant a wholesome experience in terms of body and spirit

A Search for OH Megamasers at z > 0.1. III. The Complete Survey

We present the final results from the Arecibo Observatory OH megamaser survey. We discuss in detail the properties of the remaining 18 OH megamasers detected in the survey, including 3 redetections. We place upper limits on the OH emission from 85 nondetections and examine the properties of 25 ambiguous cases for which the presence or absence of OH emission could not be determined. The complete survey has discovered 50 new OH megamasers (OHMs) in (ultra)luminous infrared galaxies ([U]LIRGs) which doubles the sample of known OHMs and increases the sample at z>0.1 sevenfold. The Arecibo OH megamaser survey indicates that the OHM fraction in LIRGs is an increasing function of the far-IR luminosity (L_{FIR}) and far-IR color, reaching a fraction of roughly one third in the warmest ULIRGs. Significant relationships between OHMs and their hosts are few, primarily due to a mismatch in size scales of measured properties and an intrinsic scatter in OHM properties roughly equal to the span of the dataset. We investigate relationships between OHMs and their hosts with a variety of statistical tools including survival analysis, partial correlation coefficients, and a principal component analysis. There is no apparent OH megamaser ``fundamental plane.'' We compile data on all previously known OHMs and evaluate the possible mechanisms and relationships responsible for OHM production in merging systems. The OH-FIR relationship is reexamined using the doubled OHM sample and found to be significantly flatter than previously thought: L_{OH} ~ L_{FIR}^{1.2 +/- 0.1}. This near-linear dependence suggests a mixture of saturated and unsaturated masers, either within individual galaxies or across the sample.Comment: 28 pages, 14 figures, accepted by AJ. (AASTeX, includes emulateapj5 and onecolfloat5

Brane-skyrmions and wrapped states

In the context of a brane world and including an induced curvature term in the brane action, we obtain the effective lagrangian for the Goldstone bosons (branons) associated with the spontaneous breaking of the translational invariance in the bulk. In addition to the branons, this effective action has Skyrmion-like solitonic states which can be understood as holes in the brane. We study their main properties such as mass and size, the Skyrmion-branon interaction and their possible fermionic quantization. We also consider states where the brane is wrapped around the extra dimensions and their relation with the brane-skyrmions. Finally, we extend our results to higher-dimensional branes, such as those appearing in M-theory, where brane-skyrmions could also be present.Comment: 35 pages, 7 figures. Revised version. Appendix and new references included. To appear in Phys. Rev.