The environmental implications of manure use in organic farming systems (OF0161)

This is the final report of Defra project OF0161. A desk study was undertaken (a) to identify the important N flows in three types of organic farming systems (extensive upland, intensive lowland mixed and stockless vegetable systems) in relation to manure use and (b) to determine the effects of changed management practice on these flows. A study of the published literature has highlighted the key stages for nutrient management prior to land spreading. Dietary inputs - amounts of N excreted and the partitioning between urine and faeces is important in determining the fate of N through the farming system. Diet affects this partition, but we were unable to find evidence of differences between organic and non-organic rations. Clearly, a crude N balance (N in feed - N in milk) provides a good guide to risk. Because N removal in milk is a small component, the more intensive systems are likely to generate more N as excreta. Housing - it is estimated that, in the UK, NH3 losses from housing constitute c. 35% of the total NH3 emissions from cattle production systems (compared with 14% from manure storage) and about 20% of total N2O emissions. The limited available information suggests that losses by NH3 emission during housing are larger from slurry based systems than from cattle housed on straw. The converse is true of N2O losses. Solid manure storage - composting offers advantages (namely sterilisation) but also can exacerbate loss of nitrogen as NH3. Losses of up to almost 80% of the total N have been reported. Our analysis of the numerous experiments suggests that the C:N ratio should be >30 at the start of composting to retain N (i.e. to reduce losses to <10%). Loose covering had little effect on retaining nitrogen. NPK are lost in leachate during manure storage (but only represent a true loss if the leachate is not collected for recycling). Slurry storage - losses are predominantly as NH3 and typically 0.05% (winter) - 0.1% (summer) of the total N content per day. A crust would approximately halve losses. Stirring increases volatilisation. Aeration would have similar effects, but may also increase N2O emissions if it produces intermittent aerobic and anaerobic conditions. Covering stores would substantially decrease losses and options range from straw to concrete structures. Effectiveness increases with cost! A simple N model was constructed to calculate the integrated effects of management practices during housing and storage. Our calculations suggested that an all-slurry system (though not permitted under organic regulations) would retain more N than a straw-based system: losses from slurry are greater during housing, less during storage (assuming the slurry lagoon is covered or has a crust and is not regularly stirred), and greater in the field (as ammonia and nitrate in particular): N losses from FYM after spreading are less, especially if composted. The question that inevitably will be asked is ‘do conventionally managed systems provide more of a risk than organic systems?’ There is no straightforward answer. Many of the loss processes from manure will be the same between systems but they will be modified by management and by the intensity of the enterprise. It is this latter point - i.e. the nutrient balance - that will have most impact on any comparison; farms with a large nutrient excess will be more prone to large losses. Thus, generally, organic farms provide less emissions than conventional farming systems involving livestock. The move to more solid-based systems should result in smaller losses of N during housing, but practical measures to reduce losses during storage need to be investigated. The outcome of all management processes is the production of manures that vary widely in composition between farms and often within farms. Our analyses of 14 cattle slurries and 45 cattle manures confirm the wide variations in nutrient contents as affected by many management factors. Generally, NPK values were c. 20-40% less than published values for ‘conventionally’ produced manures (although these mean values were also associated with a wide range of values). This probably reflects the lower intensity of organic production systems

Understanding soil fertility in organically farmed systems (OF0164)

This is the final report of the Defra project OF0164. Organic farming aims to create an economically and environmentally sustainable agriculture, with the emphasis placed on self-sustaining biological systems rather than external inputs. Building soil fertility is central to this ethos. ‘Soil fertility’ can be considered as a measure of the soil’s ability to sustain satisfactory crop growth, both in the short- and longer-term. It is determined by a set of interactions between the soil’s physical environment, chemical environment and biological activity. The aim of this project was, therefore, to provide a better scientific understanding of soil fertility under organic farming. The approach was to undertake a comprehensive literature review at the start of the project to assess and synthesise available information. Studies were then designed to address specific questions identified from the literature review. The literature review was written during the first year of the project. In addition to submitting written copies to DEFRA, the chapters were posted on a project website: www.adas.co.uk/soilfertility. The Review was based around key questions: • What are the soil organic matter characteristics and the roles of different fractions of the soil organic matter? • Do organically managed soils have higher levels of organic matter (SOM), with a resultant improvement in soil properties? • Is the soil biology different in organically managed soils, in terms of size, biodiversity and activity? • Do organically managed soils have a greater inherent capacity to supply plant nutrients? • What are the nutrient pools and their sizes? • What are the processes and rates of nutrient transfer in relation to nutrient demand? • What are the environmental consequences of organic management? The project also included a large amount of practical work. This necessarily covered a wide range of topics, which were examined in a series of separate studies: • Soil microbiology: a series of measurements focusing on two sites, undertaken by University of Wales Bangor (UWB) • Field campaigns in autumn 1999 and spring/summer 2000: separate field sampling campaigns focusing especially on nutrient pools, undertaken by HDRA, ADAS and IGER • Incubation studies: a series of three separate experiments to look in more detail at N dynamics, managed by ADAS, with support from IGER and HDRA From the literature review and the practical work, the following was concluded: Organic matter is linked intrinsically to soil fertility, because it is important in maintaining good soil physical conditions (e.g. soil structure, aeration and water holding capacity), which contribute to soil fertility. Organic matter also contains most of the soil reserve of N and large proportions of other nutrients such as P and sulphur. Field management data gathered from farmers showed, however, that organic matter returns are not necessarily larger in organic systems. Many non-organically farmed soils receive regular manure applications and the generally higher yielding crops on conventional farms may return larger crop residues. Conversely, many organic fields receive little or no manure, relying on the fertility building ley phase for organic matter input. This observation is important. Management practices within organic and non-organic systems are diverse, and all have consequences for soil fertility. The Executive Summary at the start of the main attached report has additional sections on Soil Structure, Soil Biology, and Nutrient Cycling with some greater detail on comparisons of organic and conventional management and the consequences for soil fertility

Security awareness and affective feedback:categorical behaviour vs. reported behaviour

A lack of awareness surrounding secure online behaviour can lead to end-users, and their personal details becoming vulnerable to compromise. This paper describes an ongoing research project in the field of usable security, examining the relationship between end-user-security behaviour, and the use of affective feedback to educate end-users. Part of the aforementioned research project considers the link between categorical information users reveal about themselves online, and the information users believe, or report that they have revealed online. The experimental results confirm a disparity between information revealed, and what users think they have revealed, highlighting a deficit in security awareness. Results gained in relation to the affective feedback delivered are mixed, indicating limited short-term impact. Future work seeks to perform a long-term study, with the view that positive behavioural changes may be reflected in the results as end-users become more knowledgeable about security awareness

Searching for dark matter at LHC with Mono-Higgs production

We consider LHC searches for dark matter in the mono-Higgs channel using the tools of effective field theory. This channel takes unique advantage of the presence of $SU(2)_L$ breaking in those operators to avoid the need for any initial-state radiation, usually necessary to tag the production of invisible particles. We find that sensitivities to parameters describing dark matter interactions with standard model particles are comparable to those from monojet searches for a subset of the usually-considered operators, and we present for the first time bounds from collider searches on operators which couple DM to only the Higgs field or its covariant derivatives.Comment: 13 pages, 5 figure

Inland thinning of the Amundsen Sea sector, West Antarctica

[1] Together with the Pine Island glacier (PIG), the Thwaites (TG) and Smith (SG) glaciers are the principal drainage systems of the Amundsen Sea (AS) sector of Western Antarctica. Here we use satellite radar altimetry and interferometry to show that a rapid thinning of ice has occurred within the fastest flowing sections of all AS outlet glaciers. The pattern of thinning extends to distances greater than 150 km inland. Between 1991 and 2001, the TG and SG thinned by more than 25 and 45 m at their grounding lines, and a total of 154 +/- 16 km(3) of ice (or 0.43 mm of eustatic sea level rise) was lost from the AS sector glaciers to the ocean. We show that the thickness changes may have caused the PIG, TG, and SG to retreat inland by over 8, 4, and 7 km respectively, in line with independent estimates of grounding line migration

Guide Field Dependence of 3D X-Line Spreading During Collisionless Magnetic Reconnection

Theoretical arguments and large-scale two-fluid simulations are used to study the spreading of reconnection X-lines localized in the direction of the current as a func- tion of the strength of the out-of-plane (guide) magnetic field. It is found that the mech- anism causing the spreading is different for weak and strong guide fields. In the weak guide field limit, spreading is due to the motion of the current carriers, as has been pre- viously established. However, spreading for strong guide fields is bi-directional and is due to the excitation of Alfv\'en waves along the guide field. In general, we suggest that the X-line spreads bi-directionally with a speed governed by the faster of the two mecha- nisms for each direction. A prediction on the strength of the guide field at which the spread- ing mechanism changes is formulated and verified with three-dimensional simulations. Solar, magnetospheric, and laboratory applications are discussed.Comment: 9 pages, 6 figures, Submitted to JG

A Database for Fast Access to Particle-Gated Event Data

In nuclear physics experiments involving in-flight fragmentation of ions, usually a large number of different nuclei is produced and various detection systems are employed to identify the species event by event, e.g. by measuring their specific energy loss and time-of-flight. For such cases -- not necessarily limited to nuclear physics -- where subsets of a large dataset can be identified using a small number of measured signals a software for fast access to varying subsets of such a dataset has been developed. The software has been used successfully in the analysis of a one neutron knock-out experiment at GANIL

Assessing the impact of affective feedback on end-user security awareness

A lack of awareness regarding online security behaviour can leave users and their devices vulnerable to compromise. This paper highlights potential areas where users may fall victim to online attacks, and reviews existing tools developed to raise users’ awareness of security behaviour. An ongoing research project is described, which provides a combined monitoring solution and affective feedback system, designed to provide affective feedback on automatic detection of risky security behaviour within a web browser. Results gained from the research conclude an affective feedback mechanism in a browser-based environment, can promote general awareness of online security

BlackWatch:increasing attack awareness within web applications

Web applications are relied upon by many for the services they provide. It is essential that applications implement appropriate security measures to prevent security incidents. Currently, web applications focus resources towards the preventative side of security. Whilst prevention is an essential part of the security process, developers must also implement a level of attack awareness into their web applications. Being able to detect when an attack is occurring provides applications with the ability to execute responses against malicious users in an attempt to slow down or deter their attacks. This research seeks to improve web application security by identifying malicious behaviour from within the context of web applications using our tool BlackWatch. The tool is a Python-based application which analyses suspicious events occurring within client web applications, with the objective of identifying malicious patterns of behaviour. This approach avoids issues typically encountered with traditional web application firewalls. Based on the results from a preliminary study, BlackWatch was effective at detecting attacks from both authenticated, and unauthenticated users. Furthermore, user tests with developers indicated BlackWatch was user friendly, and was easy to integrate into existing applications. Future work seeks to develop the BlackWatch solution further for public release

Reducing risky security behaviours:utilising affective feedback to educate users

Despite the number of tools created to help end-users reduce risky security behaviours, users are still falling victim to online attacks. This paper proposes a browser extension utilising affective feedback to provide warnings on detection of risky behaviour. The paper provides an overview of behaviour considered to be risky, explaining potential threats users may face online. Existing tools developed to reduce risky security behaviours in end-users have been compared, discussing the success rate of various methodologies. Ongoing research is described which attempts to educate users regarding the risks and consequences of poor security behaviour by providing the appropriate feedback on the automatic recognition of risky behaviour. The paper concludes that a solution utilising a browser extension is a suitable method of monitoring potentially risky security behaviour. Ultimately, future work seeks to implement an affective feedback mechanism within the browser extension with the aim of improving security awareness