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

Macroeconomic Forecasting with Mixed Frequency Data: Forecasting US Output Growth

Many macroeconomic series such as US real output growth are sampled quarterly, although potentially useful predictors are often observed at a higher frequency. We look at whether a mixed data-frequency sampling (MIDAS) approach can improve forecasts of output growth. The MIDAS approach is compared to other ways of making use of monthly data to predict quarterly output growth. The MIDAS specification used in the comparison employs a novel way of including an autoregressive term. We find that the use of monthly data on the current quarter leads to significant improvement in forecasting current and next quarter output growth, and that MIDAS is an effective way of exploiting monthly data compared to alternative methods. We also exploit the best method to use the monthly vintages of the indicators for real-time forecasting.Mixed data frequency, Coincident indicators, Real-time forecasting, US output growth

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

Cultural Diversity, Country Size, And The IFRS Adoption Decision

In this paper, we empirically examine the International Financial Reporting Standards (IFRS) adoption decision of 61 countries in an attempt to determine why some countries have adopted IFRS while others, at least to this point in time, have chosen not to adopt.  In particular, we examine the influence of cultural diversity and country size on the adoption decision.  Our results indicate that the IFRS adoption decision is significantly related to the size of the country, while we are unable to document any cultural influences on the decision.  Our chief result is that larger countries are less likely to adopt International Financial Reporting Standards than small countries.  This result is consistent with the notion that larger countries have a well-established set of financial accounting and reporting standards already in place, and therefore would be reluctant to incur the costs of changing to an international set of standards

Inherent Conflicts Of Interest In The Accounting Profession

In this paper, we critically examine three situations in the accounting/auditing profession in which conflicts of interest arise. Specifically, we describe conflicts of interest that occur (1) because audit fees are paid by the very companies being audited, (2) due to the tension built into accountants’ codes of professional ethics between the responsibility to maintain client confidentiality and the need to serve the public trust, and (3) because of most auditors’ perspective of who is their primary client. Based on our analysis, we conclude that these three inherent conflicts of interest, in the absence of some unforeseen revolutionary changes, are likely to persist within the auditing profession. We also conclude that attempts to mitigate some of these conflicts of interest through the Sarbanes-Oxley legislation have only been moderately successful. We therefore propose that audit professionals must learn to identify and manage the conflicts of interest that will likely remain a part of the profession for the indefinite future

Supporting Introductory Test-Driven Labs with WebIDE

WebIDE is a new web-based development environment for entry-level programmers with two primary goals: minimize tool barriers to writing computer programs and introduce software engineering best practices early in a student\u27s educational career. Currently, WebIDE focuses on Test-Driven Learning (TDL) by using small iterative examples and introducing lock-step labs, which prevent the student from moving forward until they finish the current step. However, WebIDE does not require that labs follow TDL. Instructors can write their own labs for WebIDE using any software engineering or pedagogical approach. Likewise, instructors can build custom evaluators - written in any language - to support their approach and provide detailed error messages to students. We report on a pilot study in a CS0 course where students were split into two groups, one that used WebIDE and one that didn\u27t. The WebIDE group showed a significant improvement in performance when writing a simple Android application. Additionally, among students with some programming experience, the WebIDE group was more proficient in writing unit tests

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

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