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In this paper, we propose a new 3D model for vertical-axis tidal turbines (VATTs) embedded in the shallow-water code SHYFEM. The turbine model is based on the Blade-Element∖Momentum (BEM) theory and, therefore, is able to predict turbine performance based on the local flow conditions and the geometric characteristics of the turbine. It is particularly suitable for studying turbine arrays, as it can capture the interactions between the turbines. For this reason, the model is used to test a tidal farm of 21 devices with fluid dynamic simulations. In particular, we deploy the farm at Portland Bill, which is a marine site characterised by a wide spread in the direction of the tidal currents during a flood-ebb tide cycle. We optimised the lateral and longitudinal spacing of the turbines in a fence using computational fluid dynamics simulations and then performed a sensitivity analysis by changing the distance between the fences. The results show that the greater the distance between the fences, the higher the power output. The increase in power generation is around 16%, but this implies a huge increase in the horizontal extent of the farm. Further assessments should be carried out, as the expansion of a marine area dedicated to energy exploitation may conflict with other stakeholder interests. [ABSTRACT FROM AUTHOR]

Pig production systems are currently in decline in the French Massif Central, while herbivore production systems, most of which are specialised, generate little income. The diversification of herbivore farms with pig production appears to be an interesting lever for improving farm sustainability. The objective of this study was to assess the impacts of adding pig production on the sustainability of beef and dairy farms and to assess the pros and cons of a DEA based multicriteria evaluation model. The Orfee bioeconomic model was used to simulate 17 beef or dairy farms with and without pigs. This pig production system consists of either a farrow-to-finish sow production system or a pig fattening production system only. The structural and technical parameters of these farms were established from a farm survey. Farm sustainability was assessed using 17 indicators. These indicators were hierarchically aggregated into a single sustainability composite indicator using an innovative method, the constrained directional benefit of the doubt (D-BoD) method. The results indicate that the addition of a pig production system has an overall positive impact on the sustainability of cattle farms. Mixed cattle-pig systems score significantly better on the social dimension as they generate more jobs and contribute more to food security. The overall economic performance is not significantly better than that of specialized systems for the price context from 2012 to 2022. The pig production system increases the average income per work unit for cattle farms but needs more purchased inputs to produce. This reduces but not offsets the risk reduction advantage of diversification and reduces production efficiency. Mixed farms do not score higher than specialized cattle farms on the environmental dimension. Mixed farms contribute less to global warming per kg of protein produced but have higher nitrogen and phosphorus surpluses. The constrained D-BoD method is a useful tool for endogenously aggregating indicators without having to arbitrarily set weights and thresholds to evaluate performance, but with certain limitations, such as the possibility that a farm may be judged efficient if it performs better on some indicators while being relatively weak on others. Favouring mixed farming appears to be an interesting lever for territorial development, but with two important issues: local supply of pig feed at a secure price and improved manure management to allow a virtuous cycle of nutrients. [Display omitted] • Data from 17 mixed cattle-pig farms in the French Massif Central were used. • Their farming system with or without pigs and sustainability indicators were simulated with the Orfee model. • The directional benefit of doubt method was used to estimate the composite sustainability indicators. • Pig farming systems significantly improve the overall sustainability and the social score of cattle farms. • The addition of pork operations does not result in significantly differences in economic and environmental scores. [ABSTRACT FROM AUTHOR]

Much of the global tidal current energy resource lies in the accelerated flows along narrow channels. These channels have the potential to produce 10–1000 s of MW of electricity. However, realizing 100 MW of a channel׳s potential is much more complex than installing 100 1-MW turbines because large scale power extraction reduces tidal currents throughout the channel, changing the resource. This synthesis and review gives an overview of the issues and compromises in designing the layout of the large tidal turbine arrays required to realize this potential. The paper focuses on macro- and micro-design of arrays. Macro-design relates to the total number of turbines and their gross arrangement into rows, while micro-design adjusts the relative positions of the turbines within a grid and the spacing between rows. Interdependent macro-design compromises balance the total number of turbines, array power output, the power output of each turbine, the loads the turbines experience, turbine construction costs, maintaining navigability along the channel and any environmental impacts due to flow reduction. A strong emphasis is placed on providing physical insights about how “channel-scale dynamics” and the “duct-effect” impact on the compromises in array design. This work is relevant to the design of any “large” array which blocks more than 2–5% of a channel׳s cross-section, be it 2 turbines in a small channel or 100 turbines in a large channel. [ABSTRACT FROM AUTHOR]

Agroecology is a promising alternative to industrial agriculture, with the potential to avoid the negative social and ecological consequences of input-intensive production. Transitioning to agroecological production is, however, a complex project that requires diverse contributions from the outside of scientific institutions. Agroecologists therefore collaborate with traditional producers and agroecological movements. Permaculture is one such agroecological movement, with a broad international distribution and a unique approach to system design. Despite a high public profile, permaculture has remained relatively isolated from scientific research. Though the potential contribution of permaculture to agroecological transition is great, it is limited by this isolation from science, as well as from oversimplifying claims, and the lack of a clear definition. Here, we review scientific and popular permaculture literature. A systematic review discusses quantitative bibliometric data, including keyword analysis. A qualitative review identifies and assesses major themes, proposals, and claims. The manuscript follows a stratified definition of permaculture as design system, best practice framework, worldview, and movement. The major points of our analysis are as follows: (1) Principles and topics largely complement and even extend principles and topics found in the agroecological literature. (2) Distinctive approaches to perennial polyculture, water management, and the importance of agroecosystem configuration exceed what is documented in the scientific literature and thus suggest promising avenues of inquiry. (3) Discussions of practice consistently underplay the complexity, challenges, and risks that producers face in developing diversified and integrated production systems. (4) The movement is mobilizing diverse forms of social support for sustainability, in geographically diverse locations. (5) And scholarship in permaculture has always been a diverse marginal sector, but is growing. [ABSTRACT FROM AUTHOR]

Abstract: Shelburne Farms is a non-profit environmental education center and working dairy farm located in Shelburne, Vermont, on the shores of Lake Champlain. Ecological and recreational functions of Lake Champlain have been increasingly threatened by high inputs of contaminants such as phosphorus, a high proportion of which is contributed by non-point sources including agriculture. Concerns about agricultural pollution motivated Shelburne Farms to set an example of good stewardship by applying an adaptive management process to investigate and improve water quality. The purpose of this paper is to describe both the process and outcomes as they evolved through a collaborative effort between Shelburne Farms, local stakeholders, and researchers at the University of Vermont. The adaptive management process included: (1) assessing conditions based on four years of water quality monitoring, (2) identifying and prioritizing potential solutions, (3) implementing a solution by installing a stormwater treatment system, (4) evaluating start-up performance of the treatment system, and (5) adjusting the strategy based on the results. Pre-implementation monitoring indicated that unacceptable levels of phosphorus and Escherichia coli entered the lake in runoff during storm events and that the dairy barnyard area was a significant contributor of pollutants. The stormwater treatment system, installed to treat runoff from the dairy barnyard area, reduced TSS and P concentrations within the first few months of operation on average by 25% and 43%, respectively, across all storm events. E. coli concentrations were highly variable with a mean reduction of 1% and median reduction of 78%. The adaptive management process was effective in engaging stakeholders, securing funds to implement solutions, and providing research results to inform future work. [Copyright &y& Elsevier]

groecosystems can serve as multifunctional landscapes when treed habitats such as woodlots, hedgerows, riparian buffers, windbreaks, and orchards, are conserved on farms. We investigated the extent, pattern, and multifunctionality of on-farm treed habitats for 16 Vermont farms in the Lamoille watershed of the Lake Champlain Basin. The site was selected because the land use pattern is representative of the region, containing a mixture of agriculture and forest in different habitat types. We used a GIS-based approach to delineate treed habitats on farms and conducted semi-structured interviews with farmers to explore their perception of the functions of treed habitats. Through an evaluation of the relationship between farm characteristics and spatial attributes of treed habitats, we found farm size to be an important variable. Larger farms had more land in treed habitats, while the pattern of these habitats was more complex on smaller farms. Average elevation of the farm, an indicator of biophysical conditions, was a stronger predictor of the extent of treed habitats than farm characteristics. From interviews, we found that farmers benefited from alternative forest products, both for direct consumption and sale, including firewood, timber, maple sugar, edible fruits and nuts, and wood crafts. Most farmers also recognized cultural and ecological functions provided by treed habitats. These results have implications for developing policies to promote the conservation of treed habitats, considering the preferences of the landowner or farmer. [ABSTRACT FROM AUTHOR]

Integrated crop–livestock systems (ICLS) are supposed to achieve eco-efficiency; however, its management is more complex than that of specialized systems, thereby posing a challenge for researchers, farmers, and advisors to develop coordinated actions. Besides, there is a lack of methodological approaches to support the transitions to ICLS that are important to help toward effectively crop-livestock recoupling. The Farm Coaching (FC) workshop was developed based on a blend of ICLS concepts (i.e., management of the soil-plant-animal relationships, financial resources) and personal coaching (i.e., assertive communication and time budgets). Accordingly, the objectives of this study include: (i) to analyze and discuss the potential benefits and constrains of the FC workshop; (ii) to evaluate farmers mindset change after FC; and (iii) to identify the effective actions implemented by farmers supported with specialized ICLS advising. The FC initiative was led by a private advisory company together with ICLS researchers. During each workshop, four steps are proposed: 1) deconstructing the current modus operandi , 2) going through concepts and tools to understand ICLS, 3) gaining experience through a serious game (SIPA game), and 4) co-designing a new lifestyle and production system. In addition to the workshop, the advisory company led the work on-farm that was composed of a pre-set framework, including diagnosis, co-design, and implementation. To better understand the impacts of FC, participant observation and individual interviews were conducted with 12 farmers. Four FC workshops were held between 2017 and 2019 (90 participants in total). The FC initiative successfully supported the participants' mind-set changing from specialized toward ICLS. The 12 farmers interviewed also experienced customized ICLS advice to help set up the concepts of sustainable ICLS, including whole farm design, and transition into practice. The results highlight the individual trajectories in implementing ICLS projects. Initial strategies reported for transitions included: implementing pilot projects, evaluating technical and financial indicators, organizing personal working routines, and improving teamwork skills to deal with the duties of the new concept. This study describes an original technical–personal blending approach that inspires the revision of current trends (i.e., specialized agricultural systems) and motivates farmers to act differently. The insights in this article may support ICLS agricultural initiatives in facilitating more effective mind-set changing and co-design processes. [Display omitted] • Integrated crop-livestock systems are more complex to design and implementing than specialized systems • There is a lack of methodological approaches for supporting transitions toward Integrated crop-livestock systems • Farm Coaching workshops were based on a blend of core Integrated crop-livestock systems concepts and personal coaching • A serious game was conceived to help participants experience the designing of Integrated crop-livestock systems • Farm Coaching inspires mind-set changing mind-set and on-farm advising motivates the farmers to act differently [ABSTRACT FROM AUTHOR]

The development of the mussel ( Mytilus edulis) farming industry in Norway is based on suspended long-line culture, and large areas of the coast are potentially suitable for farming. Norwegian fjords and coastal waters are regarded as oligotrophic environments in comparison with sites where most studies on mussel feeding on natural seston have been carried out. High mussel culture densities in oligotrophic water may cause seston depletion, resulting in low growth or tissue wasting due to reduced feeding and negative net energy balance. In this paper we present a carrying capacity model based on rate conditional processes, balanced against flushing and with emphasis on flow reduction as a function of farm design. The model is based on assumptions that friction forces are a function of geometric shape of the channel made up by the suspended mussel ropes as vertical boundaries and it quantifies carrying capacity according to information of farm length, space between long lines, seston concentration and background current speed and the relative importance of these factors. Estimates of how stocking density in mussel farming can be optimized in relation to the food supply (i.e. carrying capacity) are crucial to production management decisions, and the model may provide predictors for decisions regarding new site selection or expansion of existing operations. [ABSTRACT FROM AUTHOR]

A mathematical simulation model was used to assist 5 farmers in developing design criteria for inclusion of robotic milking systems in each farm situation. The barn layout influences arrivals of cows to the milking robot as well as other cow traffic and must be carefully planned. Each farmer had individual objectives and consequently unique design criteria that determined the optimal solution. Planning factors addressed by simulations on these farms included: 1) optimal cow cooling locations; 2) optimal facility allocation in expanding dairies; 3) concentrate feeder locations and feeding management; 4) number of feeders--based on expected rations; 5) use of a robot in an open cowshed without free stalls; 6) number of robots needed, currently and in the future; 7) eight robots working in harmony; 8) robot locations that allow for expansion; 9) floor space needed in each barn section including maternity and veterinary treatment areas; 10) location of bottlenecks that limit efficiency or expansion; and 11) cow traffic routine as affected by management practices, feed allocation, and farm layout. The simulation allowed farmers to receive a course in managing a "virtual robotic milking farm" before installation of the barn. Therefore, each could be more confident that his future barn would work properly under his unique local conditions and management practices. One farm checked 2 yr after construction achieved an average daily robot utilization of 84%, nearly matching the 85% projected before the barn was built. Important variables considered in the simulations were facility allocation, cow space needed in each farm area, robot utilization, number of cows, milk yield, milk flow rate, feeding method and timing, robot location and orientation, and farm physical layout. [ABSTRACT FROM AUTHOR]

The design of various conventional dairy barns is based on centuries of experience, but there is hardly any experience with robotic milking barns (RMB). Furthermore, as each farmer has his own management practices, the optimal layout is ‘site dependent’. A new universally applicable design methodology has been developed, to overcome this lack of experience with RMBs and to facilitate the designing of their optimal layout. This model for optimizing facility allocation, based on cow behaviour, welfare needs, and facility utilization, uses queuing network theory, Markov process, and heuristic optimization. The methodology has been programmed into a software application, supporting the design process. On a particular farm, presented later as a case study, numerical results include: if the herd contains more than 50 cows, the forage-lane utilization is greater than 70% (or idle time is less than 30%). To meet animal-welfare demands, the herd size should not exceed 60 cows. Therefore, the herd should comprise 50–60 cows. In the second scenario examined, the average robot idle time was 25%, queue length was three cows, and each cow waited for about 3 min at the robot. It is still uncommon to apply techniques from queuing-network theory to livestock housing, and this study demonstrates their potential as practical design tools that meet both economic and animal welfare needs. [Copyright &y& Elsevier]