Environmental friendly nitrogen fertilization

With the huge intensification of agriculture and the increasing awareness to human health and natural resources sustainability, there was a shift towards the development of environmental friendly N application approaches that support sustainable use of land and sustain food production. The effectiveness of such approaches depends on their ability to synchronize plant nitrogen demand with its supply and the ability to apply favored compositions and dosages of N-species. They are also influenced by farming scale and its sophistication, and include the following key concepts: (i) Improved application modes such as split or localized ("depot") application; (ii) use of bio-amendments like nitrification and urease inhibitors and combinations of (i) and (ii); (iii) use of controlled and slow release fertilizers; (iv) Fertigation-fertilization via irrigation systems including fully automated and controlled systems; and (v) precision fertilization in large scale farming systems. The paper describes the approaches and their action mechanisms and examines their agronomic and environmental significance. The relevance of the approaches for different farming scales, levels of agronomic intensification and agro-technical sophistication is examined as well.     

Environmental friendly nitrogen fertilization

With the huge intensification of agriculture and the increasing awareness to human health and natural resources sustainability, there was a shift towards the development of environmental friendly N application approaches that support sustainable use of land and sustain food production.

The effectiveness of such approaches depends on their ability to synchronize plant nitrogen demand with its supply and the ability to apply favored compositions and dosages of N-species. They are also influenced by farming scale and its sophistication, and include the following key concepts: (i) Improved application modes such as split or localized (“depot”) application; (ii) use of bio-amendments like nitrification and urease inhibitors and combinations of (i) and (ii); (iii) use of controlled and slow release fertilizers; (iv) Fertigation-fertilization via irrigation systems including fully automated and controlled systems; and (v) precision fertilization in large scale farming systems. The paper describes the approaches and their action mechanisms and examines their agronomic and environmental significance. The relevance of the approaches for different farming scales, levels of agronomic intensification and agro-technical sophistication is examined as well.

     

Mixed crop-livestock systems: an economic and environmental-friendly way of farming?

Intensification and specialisation of agriculture in developed countries enabled productivity to be improved but had detrimental impacts on the environment and threatened the economic viability of a huge number of farms. The combination of livestock and crops, which was very common in the past, is assumed to be a viable alternative to specialised livestock or cropping systems. Mixed crop-livestock systems can improve nutrient cycling while reducing chemical inputs and generate economies of scope at farm level. Most assumptions underlying these views are based on theoretical and experimental evidence. Very few assessments of their environmental and economic advantages have nevertheless been undertaken in real-world farming conditions. In this paper, we present a comparative assessment of the environmental and economic performances of mixed crop-livestock farms v. specialised farms among the farm population of the French ‘Coteaux de Gascogne’. In this hilly region, half of the farms currently use a mixed crop-livestock system including beef cattle and cash crops, the remaining farms being specialised in either crops or cattle. Data were collected through an exhaustive survey of farms located in our study area. The economic performances of farming systems were assessed on 48 farms on the basis of (i) overall gross margin, (ii) production costs and (iii) analysis of the sensitivity of gross margins to fluctuations in the price of inputs and outputs. The environmental dimension was analysed through (i) characterisation of farmers’ crop management practices, (ii) analysis of farm land use diversity and (iii) nitrogen farm-gate balance. Local mixed crop-livestock farms did not have significantly higher overall gross margins than specialised farms but were less sensitive than dairy and crop farms to fluctuations in the price of inputs and outputs considered. Mixed crop-livestock farms had lower costs than crop farms, while beef farms had the lowest costs as they are grass-based systems. Concerning crop management practices, our results revealed an intensification gradient from low to high input farming systems. Beyond some general trends, a wide range of management practices and levels of intensification were observed among farms with a similar production system. Mixed crop-livestock farms were very heterogeneous with respect to the use of inputs. Nevertheless, our study revealed a lower potential for nitrogen pollution in mixed crop-livestock and beef production systems than in dairy and crop farming systems. Even if a wide variability exists within system, mixed crop-livestock systems appear to be a way for an environmental and economical sustainable agriculture.     

Modelling as a tool to redesign livestock farming systems: a literature review

Livestock farming has recently come under close scrutiny, in response especially to environmental issues. Farmers are encouraged to redesign their livestock farming systems in depth to improve their sustainability. Assuming that modelling can be a relevant tool to address such systemic changes, we sought to answer the following question: ‘How can livestock farming systems be modelled to help farmers redesign their whole farming systems?’ To this end, we made a literature review of the models of livestock farming systems published from 2000 to mid-2009 (n = 79). We used an analysis grid based on three considerations: (i) system definition, (ii) the intended use of the model and (iii) the way in which farmers’ decision-making processes were represented and how agricultural experts and farmers were involved in the modelling processes. Consistent rationales in approaches to supporting changes in livestock farming were identified in three different groups of models, covering 83% of the whole set. These could be defined according to (i) the way in which farmers’ decisions were represented and (ii) the model's type of contribution to supporting changes. The first type gathered models that dynamically simulated the system according to different management options; the farmers’ decision-making processes are assumed to consist in choosing certain values for management factors. Such models allow long-term simulations and endorse different disciplinary viewpoints, but the farmers are weakly involved in their design. Models of the second type can indicate the best combination of farm activities under given constraints, provided the farmers’ objectives are profit maximisation. However, when used to support redesigning processes, they address neither how to implement the optimal solution nor its long-term consequences. Models of the third type enable users to dynamically simulate different options for the farming system, the management of which is assumed to be planned according to the farmers’ general objectives. Although more comprehensive, these models do not easily integrate different disciplinary viewpoints and different subsystems, which limits their usefulness as support tools for redesigning processes. Finally, we concluded about what specific requirements should be for modelling approaches if farmers were to be supported in redesigning their whole livestock farming systems using models.     

AM真菌在有机农业发展中的机遇

在农田生态系统中,许多农作物均为丛枝菌根(AM)真菌的优良宿主植物,当AM真菌与这些宿主植物建立共生关系之后,AM真菌的存在有益于宿主植物的生长。然而,传统农业耕作模式中化学肥料和农药的施用、耕作制度的不断调整和非宿主植物的种植等都不利于AM真菌的建植。有机农业生态系统排除了化学肥料和农药的施用,减少了对AM真菌生长不利的因素,促进了土壤中AM真菌数量的增加和群落多样性的提高。同时,AM真菌可以通过多种方式改善土壤物理结构、提高农作物对干旱胁迫的耐受能力以及宿主植物对病虫害的抗性/耐性、抑制杂草生长、促进营养物质的吸收,进而提高植物的生长和改善产品的品质。基于此,围绕AM真菌在有机农业发展中的生态学功能展开论述,分析当前有机农业生态系统存在的问题,探讨利用AM真菌发展有机农业的可行性及其发展的机遇,以期促进AM真菌在有机农业发展中的应用。     

Prospects from agroecology and industrial ecology for animal production in the 21st century

Agroecology and industrial ecology can be viewed as complementary means for reducing the environmental footprint of animal farming systems: agroecology mainly by stimulating natural processes to reduce inputs, and industrial ecology by closing system loops, thereby reducing demand for raw materials, lowering pollution and saving on waste treatment. Surprisingly, animal farming systems have so far been ignored in most agroecological thinking. On the basis of a study by Altieri, who identified the key ecological processes to be optimized, we propose five principles for the design of sustainable animal production systems: (i) adopting management practices aiming to improve animal health, (ii) decreasing the inputs needed for production, (iii) decreasing pollution by optimizing the metabolic functioning of farming systems, (iv) enhancing diversity within animal production systems to strengthen their resilience and (v) preserving biological diversity in agroecosystems by adapting management practices. We then discuss how these different principles combine to generate environmental, social and economic performance in six animal production systems (ruminants, pigs, rabbits and aquaculture) covering a long gradient of intensification. The two principles concerning economy of inputs and reduction of pollution emerged in nearly all the case studies, a finding that can be explained by the economic and regulatory constraints affecting animal production. Integrated management of animal health was seldom mobilized, as alternatives to chemical drugs have only recently been investigated, and the results are not yet transferable to farming practices. A number of ecological functions and ecosystem services (recycling of nutrients, forage yield, pollination, resistance to weed invasion, etc.) are closely linked to biodiversity, and their persistence depends largely on maintaining biological diversity in agroecosystems. We conclude that the development of such ecology-based alternatives for animal production implies changes in the positions adopted by technicians and extension services, researchers and policymakers. Animal production systems should not only be considered holistically, but also in the diversity of their local and regional conditions. The ability of farmers to make their own decisions on the basis of the close monitoring of system performance is most important to ensure system sustainability.     

Consequential Life Cycle Assessment of Pasture‐based Milk Production: A Case Study in the Waikato Region,New Zealand

Farm intensification options in pasture‐based dairy systems are generally associated with increased stocking rates coupled with the increased use of off‐farm inputs to support the additional feed demand of animals. However, as well as increasing milk production per hectare, intensification can also exacerbate adverse impacts on the environment. The objective of the present study was to investigate environmental trade‐offs associated with potential intensification methods for pasture‐based dairy farming systems in the Waikato region, New Zealand. The intensification scenarios selected were (1) increased pasture utilization efficiency (PUE scenario), (2) increased use of nitrogen (N) fertilizer to boost on‐farm pasture production (N fertilizer scenario), and (3) increased use of brought‐in feed as maize silage (MS) (MS scenario). Twelve impact categories were assessed. The PUE scenario was the environmentally preferred intensification method, and the preferred choice between the N fertilizer and MS scenarios depended upon trade‐offs between different environmental impacts. Sensitivity analysis was carried out to test the effects of choice associated with: (1) the approaches used to account for indirect land‐use change (ILUC) and (2) the competing product systems (conventional beef systems) used to handle the co‐product dairy meat for the climate change (CC) indicator. Results showed that the magnitude of the CC indicator results was influenced by the ILUC accounting approaches and the choice associated with a global marginal beef mix, but the relative CC indicator results for the three intensification scenarios remained unchanged.     

Clean Biotechnology for Sustainable Farming

Sustainability would never be achieved farewell as agricultural practices continue beyond the carrying capacity of the ecosystem through the exaggerated abuse of agricultural chemicals. The rapid growth of agricultural productivity in chemical farming systems is shrinking off. Moreover, environmental torrent from agricultural activities jeopardizes agricultural growth in several countries. Problems associated with the wealthy agricultural production in the developed world and underproduction in developing countries necessitate a widely accepted assessment of the present status of agriculture. It is time to install new farming systems committed to following environmental and sustainable approaches, and producing healthy food free from agrochemical residues. Ecologically oriented farming routines are being developed within the frame of the recent achievements in environmental biotechnology, the most important of which is the clean farming system which is increasingly acknowledged as a potential solution to copious problems overlaying present world agriculture. It is a farming system, which aims at evading the routine use of agricultural chemicals and reducing their rates of application. Clean farming systems directly give rise to four environmental biotechnologies, i.e., recycling of composted organic waste, fortifying the rhizosphere soil with biofertilizers, encouraging the use of biopesticides in agricultural practices and bioremediation of polluted agro‐ecosystems.     

High-throughput molecular analyses of microbiomes as a tool to monitor the wellbeing of aquatic environments

Aquatic environments are the recipients of many sources of environmental stress that trigger both local and global changes. To evaluate the associated risks to organisms and ecosystems more sensitive and accurate strategies are required. The analysis of the microbiome is one of the most promising candidates for environmental diagnosis of aquatic systems. Culture-independent interconnected meta-omic approaches are being increasing used to fill the gaps that classical microbial approaches cannot resolve. Here, we provide a prospective view of the increasing application of these high-throughput molecular technologies to evaluate the structure and functional activity of microbial communities in response to changes and disturbances in the environment, mostly of anthropogenic origin. Some relevant topics are reviewed, such as: (i) the use of microorganisms for water quality assessment, highlighting the incidence of antimicrobial resistance as an increasingly serious threat to global public health; (ii) the crucial role of microorganisms and their complex relationships with the ongoing climate change, and other stress threats; (iii) the responses of the environmental microbiome to extreme pollution conditions, such as acid mine drainage or oil spills. Moreover, protists and viruses, due to their huge impacts on the structure of microbial communities, are emerging candidates for the assessment of aquatic environmental health.     

Integrated physiological and agronomic modelling of N capture and use within the plant

Today farmers have several constraints to take into account in managing their crops: (i) competitiveness: productivity must be maintained or increased whereas inputs must be decreased, (ii) the environmental consequences of cultural practices: pesticide and fertilizer use must be decreased, and (iii) product quality must be improved and nitrogen nutrition is an important factor in harvest quality. These new constraints sometimes conflict: maximum yield is often obtained with large amounts of N, increasing the risks of N leaching. The determination of rates and dates for nitrogen application must become more precise in this context. Tools are required for the forecasting of crop requirements, the diagnosis of N deficiencies during the crop cycle and breeding of new adapted varieties. Models and diagnosis indicators have been developed to meet these needs, but those relating to nitrogen are often based on empirical relationships. Moreover, the available models and indicators often fail to account for cultivar-specific responses. The improvement of agronomic tools and the breeding of new varieties adapted to new cropping systems should be based on a thorough understanding of the key metabolic processes involved, and the relative contributions of these processes to yield determination in conditions of fluctuating N supply. For both purposes, more information is required about plant and crop N economy. In this paper, the way in which N absorption and use within the plant and crop, plant responses to deficiencies and excesses of nitrogen are taken into account in major agronomic models is described first. The level of sophistication of the modules comprising these models depends on operational objectives. Secondly, the ways in which the most recent molecular plant physiology findings can, and indeed should, be integrated into models at the crop and crop cycle levels are described. The potential value of this approach for improving current agronomic models and diagnostic tools, and for breeding more efficient varieties is also discussed.     

Population and agricultural intensity in the humid tropics

A review of models of agricultural intensification and their application to the agricultural systems of the humid tropics is presented. Taken into account are the distributions of these systems at various population densities, available data on labor efficiencies, the costs of establishing continuous cropping, and data regarding soils under cultivation and various types of fallow. The findings that fallows much longer than 10 or 15 years serve no known agronomic function, that given preindustrial technology, grass fallows are disadvantageous, even environmentally destructive, and that continuous cropping usually entails a considerable amount of environmental modification support the interpretations that agricultural intensification in the humid tropics is best understood in terms of ecologically optimal strategies at different population densities. Points needing further investigation are highlighted: the reasons for very long fallows, and the comparative labor efficiencies of fallow and continuous cropping systems where crops and environments are similar.     

Review: Precision livestock farming,automats and new technologies: possible applications in extensive dairy sheep farming

Precision livestock farming (PLF) technologies are becoming increasingly common in modern agriculture. They are frequently integrated with other new technologies in order to improve human–livestock interactions, productivity and economical sustainability of modern farms. New systems are constantly being developed for concentrated farming operations as well as for extensive and pasture-based farming systems. The development of technologies for grazing animals is of particular interest for the Mediterranean extensive sheep farming sector. Dairy sheep farming is a typical production system of the area linked to its historical and cultural traditions. The area provides roughly 40% of the world sheep milk, having 27% of the milk-producing ewes. Developed countries of the area (France, Italy, Greece and Spain – FIGS) have highly specialized production systems improved through animal selection, feeding techniques and intensification of production. However, extensive systems are still practiced alongside intensive ones due to their lower input costs and better resilience to market fluctuations. In the current article, we evaluate possible PLF systems and their suitability to be incorporated in extensive dairy sheep farming as practiced in the FIGS countries. Available products include: electronic identification systems (now mandatory in the EU) such as ear tags, ruminal boluses and sub-cutaneous radio-frequency identification; on-animal sensors such as accelerometers, global positioning systems and social activity loggers; and stationary management systems such as walk-over-weights, automatic drafter (AD), virtual fencing and milking parlour-related technologies. The systems were considered according to their suitability for the management and business model common in dairy sheep farming. However, adoption of new technologies does not take place immediately in small and medium scale extensive farming. As sheep farmers usually belong to more conservative technology consumers, characterized by an average age of 60 and a very transparent community, the dynamics do not favour financial risk taking involved with new technologies. Financial barriers linked to production volumes and resource management of extensive farming are also a barrier for innovation. However, future prospectives could increase the importance of technology and promote its wider adoption. Trends such as global sheep milk economics, global warming, awareness to animal welfare, antibiotics resistance and European agricultural policies could influence the farming practices and stimulate wider adoption of PLF systems in the near future.     

Review: Associations among goods,impacts and ecosystem services provided by livestock farming

Livestock is a major driver in most rural landscapes and economics, but it also polarises debate over its environmental impacts, animal welfare and human health. Conversely, the various services that livestock farming systems provide to society are often overlooked and have rarely been quantified. The aim of analysing bundles of services is to chart the coexistence and interactions between the various services and impacts provided by livestock farming, and to identify sets of ecosystem services (ES) that appear together repeatedly across sites and through time. We review three types of approaches that analyse associations among impacts and services from local to global scales: (i) detecting ES associations at system or landscape scale, (ii) identifying and mapping bundles of ES and impacts and (iii) exploring potential drivers using prospective scenarios. At a local scale, farming practices interact with landscape heterogeneity in a multi-scale process to shape grassland biodiversity and ES. Production and various ES provided by grasslands to farmers, such as soil fertility, biological regulations and erosion control, benefit to some extent from the functional diversity of grassland species, and length of pasture phase in the crop rotation. Mapping ES from the landscape up to the EU-wide scale reveals a frequent trade-off between livestock production on one side and regulating and cultural services on the other. Maps allow the identification of target areas with higher ecological value or greater sensitivity to risks. Using two key factors (livestock density and the proportion of permanent grassland within utilised agricultural area), we identified six types of European livestock production areas characterised by contrasted bundles of services and impacts. Livestock management also appeared to be a key driver of bundles of services in prospective scenarios. These scenarios simulate a breakaway from current production, legislation (e.g. the use of food waste to fatten pigs) and consumption trends (e.g. halving animal protein consumption across Europe). Overall, strategies that combine a reduction of inputs, of the use of crops from arable land to feed livestock, of food waste and of meat consumption deliver a more sustainable food future. Livestock as part of this sustainable future requires further enhancement, quantification and communication of the services provided by livestock farming to society, which calls for the following: (i) a better targeting of public support, (ii) more precise quantification of bundles of services and (iii) better information to consumers and assessment of their willingness to pay for these services.     

Yield stability: an agronomic perspective on the origin of Near Eastern agriculture

Here we argue that, based on evolutionary, ecological and agronomic considerations, climate change could not have been a suitable background nor a probable cause of plant domestication in the Near East. This thesis is developed based on the year-to-year yield dynamics in traditional rainfed grain farming in semi-arid environments, on the genetic basis that underlies temporal yield dynamics in natural wild cereal populations as well as in traditional farming systems, and upon the recognition that prior to elaborate high capacity and long-range trade networks, yield stability was more important than yield maximization. We also briefly discuss the likely social and cultural responses to subtle and real climatic changes vs. responses to rapid directional environmental trends. Taking into account the agronomic, ecological and genetic aspects discussed, it is suggested that the Near Eastern founder crop assemblage was chosen to function within the normal east Mediterranean precipitation regime, in which good rainy years create the ‘normal surplus’ that sustains farming communities during drought years, and the different crop types provide the system with its compensating ability. A slow (but real) climatic change is unlikely to induce major (revolutionary) cultural changes. Nor would a prominent environmental change provide the proper background for the origins of agriculture because it would abolish the buffering capacity of the system. Therefore, farming cannot function as a sustainable ‘buffering mechanism’ to counterbalance climatic instability causing natural resource depletion.     

Estimating the human appropriation of land in Brazil by means of an Input–Output Economic Model and Ecological Footprint analysis

As we confront the current environmental crisis, determining the biophysical base (e.g., materials, energy, land, and water) of nations has become paramount. With advanced economies benefiting from the import of resource-intensive primary goods originating from poorer parts of the world, especially emerging nations, these are dilapidating their natural capital. Brazil is one of such emerging economies, whose mining and farming activities, propping up its export-led economic growth, exert great pressure on the environment. In particular, farming has been shown to have one of the world's greatest environmental impacts, especially as a consequence of land use associated with cattle ranching. Since a nation-wide evaluation of land-use types across the whole sectorial spectrum of the country's economy is still lacking, we used the most recently available Input–Output Economic Model for Brazil and the Ecological Footprint method to identify those economic sectors with the greatest potential for appropriating portions of the natural world.Our results show that: (i) the biggest chunk of Brazil's Ecological Footprint is due to its Carbon Footprint and, in particular, emissions from cattle; (ii) only a few economic sectors exhibit high Ecological Footprint values, chiefly those belonging to livestock farming and energy production based on fossil fuels; (iii) excluding the soybeans and slaughter sectors, export-oriented sectors have below-average Ecological Footprint values; and (iv) the percentage of Brazil's Ecological Footprint due to household consumption (excluding imports) is three times bigger than that attributable to exports, with sectors belonging to livestock farming contributing the most to such disparity.These results underscore that the environmental impact of the Brazilian economy can be drastically reduced by tackling the emission-intensive production processes of a few sectors only and disincentivizing the domestic consumption of a narrow range of products, especially with respect to the livestock segment.     

Exploiting Co-Benefits of Increased Rice Production and Reduced Greenhouse Gas Emission through Optimized Crop and Soil Management

Meeting the future food security challenge without further sacrificing environmental integrity requires transformative changes in managing the key biophysical determinants of increasing agronomic productivity and reducing the environmental footprint. Here, we focus on Chinese rice production and quantitatively address this concern by conducting 403 on-farm trials across diverse rice farming systems. Inherent soil productivity, management practices and rice farming type resulted in confounded and interactive effects on yield, yield gaps and greenhouse gas (GHG) emissions (N₂O, CH₄ and CO₂-equivalent) with both trade-offs and compensating effects. Advances in nitrogen, water and crop management (Best Management Practices—BMPs) helped closing existing yield gaps and resulted in a substantial reduction in CO₂-equivalent emission of rice farming despite a tradeoff of increase N₂O emission. However, inherent soil properties limited rice yields to a larger extent than previously known. Cultivating inherently better soil also led to lower GHG intensity (GHG emissions per unit yield). Neither adopting BMPs only nor improving soils with low or moderate productivity alone can adequately address the challenge of substantially increasing rice production while reducing the environmental footprint. A combination of both represents the most efficient strategy to harness the combined-benefits of enhanced production and mitigating climate change. Extrapolating from our farm data, this strategy could increase rice production in China by 18%, which would meet the demand for direct human consumption of rice by 2030. It would also reduce fertilizer nitrogen consumption by 22% and decrease CO₂-equivalent emissions during the rice growing period by 7% compared with current farming practice continues. Benefits vary by rice-based cropping systems. Single rice systems have the largest food provision benefits due to its wider yield gap and total cultivated area, whereas double-rice system (especially late rice) contributes primarily to reducing GHG emissions. The study therefore provides farm-based evidence for feasible, practical approaches towards achieving realistic food security and environmental quality targets at a national scale.     

Ecological and environmental footprint of 50 years of agricultural expansion in Argentina

Agriculture expanded during the last 50 years from the Pampas to NW Argentina at the expense of natural forests and rangelands. In parallel, productivity was boosted through the increasing application of external inputs, modern technology and management practices. This study evaluated the impact of agricultural expansion between 1960 and 2005 by assessing the implications of land use, technology and management changes on (i) carbon (C), nitrogen (N) and phosphorous (P) stocks in soil and biomass, (ii) energy, C, N, P and water fluxes and (iii) water pollution, soil erosion, habitat intervention and greenhouse gas (GHG) emissions (impacts). Based on different data sources, these issues were assessed over～1.5 million km² (63% of Argentina), involving 399 political districts during three representative periods: 1956–1960, 1986–1990 and 2001–2005. The ecological and environmental performance of 1197 farming system types was evaluated through the AgroEcoIndex model, which quantified the stocks, fluxes and impacts mentioned above. Cultivation of natural ecosystems and farming intensification caused a noticeable increase of productivity, a strengthening of energy flux, an opening of matter cycles (C, N, P) and a negative impact on habitats and GHGs emission. However, due to the improved tillage practices and the application of less aggressive pesticides, erosion and pollution risk are today lower than those of the mid‐20th century. The consistency of some assumptions and results were checked through uncertainty analysis. Comparing our results with international figures, some impacts (e.g. soil erosion, nutrient balance, energy use) were less significant than those recorded in intensive‐farming countries like China, Japan, New Zealand, USA, or those of Western Europe, showing that farmers in Argentina developed the capacity to produce under relatively low‐input/low‐impact schemes during the last decades. [Correction added after online publication 4 October 2010: In the first sentence of the Abstract, NE was corrected to NW.]     

Paths to last in mixed crop–livestock farming: lessons from an assessment of farm trajectories of change

Mixed crop–livestock systems, combining livestock and cash crops at farm level, are considered to be suitable for sustainable intensification of agriculture. Ensuring the survival of mixed crop–livestock systems is a challenge for European agriculture: the number of European mixed crop–livestock farms has been decreasing since 1970. Analysis of farming system dynamics may elucidate past changes and the forces driving this decline. The objectives of this study were (i) to identify the diversity of paths that allowed the survival of mixed crop–livestock farming and (ii) to elucidate the driving forces behind such survival. We analysed the variety of farm trajectories from 1950 to 2005. We studied the entire farm population of a case study site, located in the ‘Coteaux de Gascogne’ region. In this less favoured area of south-western France, farmers have limited specialisation. Currently, half of the farms use mixed crop–livestock systems. The data set of 20 variables for 50 farms on the basis of six 10-year time steps was collected through retrospective surveys. We used a two-step analysis including (i) a visual assessment of the whole population of individual farm trajectories and (ii) a computer-based typology of farm trajectories on the basis of a series of multivariate analyses followed by automatic clustering. The European Common Agricultural Policy, market globalisation and decreasing workforce availability were identified as drivers of change that favoured the specialisation process. Nevertheless, farmers’ choices and values have opposed against these driving forces, ensuring the survival of some mixed crop–livestock farming systems. The trajectories were clustered into five types, four of which were compatible with mixed crop–livestock systems. The first type was the maximisation of autonomy by combining crops and livestock. The second type was diversification of production to exploit economies of scope and protect the farm against market fluctuations. The other two types involved enlargement and progressive adaptation of the farm to the familial workforce. The survival of mixed crop–livestock systems in these two types is largely dependent on workforce availability. Only one type of trajectory, on the basis of enlargement and economies of scale, did not lead to mixed crop–livestock systems. In view of the current evolution of the driving forces, maximising autonomy and diversification appear to be suitable paths to deal with current challenges and maintain mixed crop–livestock systems in Europe.     

Assessing Compositional Variability through Graphical Analysis and Bayesian Statistical Approaches: Case Studies on Transgenic Crops

Abstract

New transgenic (GM) crops are subjected to extensive safety assessments that include compositional comparisons with conventional counterparts as a cornerstone of the process. The influence of germplasm, location, environment, and agronomic treatments on compositional variability is, however, often obscured in these pair-wise comparisons. Furthermore, classical statistical significance testing can often provide an incomplete and over-simplified summary of highly responsive variables such as crop composition. In order to more clearly describe the influence of the numerous sources of compositional variation we present an introduction to two alternative but complementary approaches to data analysis and interpretation. These include i) exploratory data analysis (EDA) with its emphasis on visualization and graphics-based approaches and ii) Bayesian statistical methodology that provides easily interpretable and meaningful evaluations of data in terms of probability distributions. The EDA case-studies include analyses of herbicide-tolerant GM soybean and insect-protected GM maize and soybean. Bayesian approaches are presented in an analysis of herbicide-tolerant GM soybean. Advantages of these approaches over classical frequentist significance testing include the more direct interpretation of results in terms of probabilities pertaining to quantities of interest and no confusion over the application     

Metacommunity organisation,spatial extent and dispersal in aquatic systems: patterns,processes and prospects

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