Increased Productivity of a Cover Crop Mixture Is Not Associated with Enhanced Agroecosystem Services

Cover crops provide a variety of important agroecological services within cropping systems. Typically these crops are grown as monocultures or simple graminoid-legume bicultures; however, ecological theory and empirical evidence suggest that agroecosystem services could be enhanced by growing cover crops in species-rich mixtures. We examined cover crop productivity, weed suppression, stability, and carryover effects to a subsequent cash crop in an experiment involving a five-species annual cover crop mixture and the component species grown as monocultures in SE New Hampshire, USA in 2011 and 2012. The mean land equivalent ratio (LER) for the mixture exceeded 1.0 in both years, indicating that the mixture over-yielded relative to the monocultures. Despite the apparent over-yielding in the mixture, we observed no enhancement in weed suppression, biomass stability, or productivity of a subsequent oat (Avena sativa L.) cash crop when compared to the best monoculture component crop. These data are some of the first to include application of the LER to an analysis of a cover crop mixture and contribute to the growing literature on the agroecological effects of cover crop diversity in cropping systems

Strategies for simulating the transition to agroforestry in Quebec, Canada

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Farmers' management of rice varietal diversity in the mid-hills of Nepal: implications for on-farm conservation and crop improvement

Season-long monitoring of on-farm rice (Oryza sativa, L.) plots in Nepal explored farmers' decision-making process on the deployment of varieties to agroecosystems, application of production inputs to varieties, agronomic practices and relationship between economic return and area planted per variety. Farmers deploy varieties [landraces (LRs) and modern varieties (MVs)] to agroecosystems based on their understanding of characteristics of varieties and agroecosystems, and the interaction between them. In marginal growing conditions, LRs can compete with MVs. Within an agroecosystem, economic return and area planted to varieties have positive relationship, but this is not so between agroecosystems. LRs are very diverse on agronomic and economic traits; therefore, they cannot be rejected a priori as inferior materials without proper evaluation. LRs have to be evaluated for useful traits and utilized in breeding programmes to generate farmer-preferred materials for marginal environments and for their conservation on-farm

The Community Ecology of Herbivore Regulation in an Agroecosystem: Lessons from Complex Systems

AbstractWhether an ecological community is controlled from above or below remains a popular framework that continues generating interesting research questions and takes on especially important meaning in agroecosystems. We describe the regulation from above of three coffee herbivores, a leaf herbivore (the green coffee scale, Coccus viridis), a seed predator (the coffee berry borer, Hypothenemus hampei), and a plant pathogen (the coffee rust disease, caused by Hemelia vastatrix) by various natural enemies, emphasizing the remarkable complexity involved. We emphasize the intersection of this classical question of ecology with the burgeoning field of complex systems, including references to chaos, critical transitions, hysteresis, basin or boundary collision, and spatial self-organization, all aimed at the applied question of pest control in the coffee agroecosystem

The well-proportioned farm organism. Just a pleasing image of a mixed farming system or rather a basic requirement for functioning organic husbandry?

The basic references and textbooks of organic farming describe this agricultural method as aiming at and using the benefits of a certain farm structure. Similar concepts and ideas of a farm have been described both by the pioneers of organic farming and by the pioneers of agricultural sciences, although using various terms: agricultural individuality (Steiner in 1924), self-sufficient organic whole (Lord Northbourne in 1940), the proportioned farm (Young in 1770), the farm organism (Koepf in 1976), the branches of a farm are like organs in a body (Aereboe in 1920) having a certain size and being dependent from each other (Brinkmann in 1922). The various terms, ideas and aspects are explained and compared with each other. In the 1970s and 1980s, some decades later than most of these references have been published, scientific activities called ecosystem research have been undertaken to investigate the structures and processes in natural or almost natural ecosystems as well as in agricultural ecosystems. Particularly, the effects and the significance of human impact (e.g. tillage, fertilization, plant protection) as regards structure, functioning and long-term stability or productivity of agroecosystems have been investigated. These results considered in the light of experiences gained in both organic and conventional farming practice can explain the linkage between structures and functions of a farm, i.e. why not only a certain diversity but also a ceratin set of operation (“impacts”) is necessary for the long-term fertility and sustainability of a farm if it is managed organically. Different, partly the opposite consequences can be observed with the specialisation versus the diversification of the farm organism. The effects of agronomic tools and techniques mainly depend on whether they support the ability of self-regulation in agroecosystems or they act as an external (anthropogenic) regulation, as different types of feedback can be provoked in the system. The paper is a contribution to the general concept of organic farming and to the present tendency in organic farming practice to accept more simple, specialized farms

Farm enterprises as self-organizing systems: A new transdisciplinary framework for studying farm enterprises?

The growing attention to sustainable food production and multifunctional agriculture calls for a multidisciplinary or transdisciplinary research and development perspective on farming, which is able to grasp the environmental, social, technical, and financial aspects of a farm and the dynamic relationship between the farm enterprises and the surrounding world. Our thesis is that a transdisciplinary approach needs to build on a working ontology that goes beyond the epistemology of each discipline and that is not just pieced together of the ontologies connected to these different epistemologies. Based on a review of three prevailing theoretical frameworks within the field of agro-sociology: The farming styles approach, the Bawden approach, and Conway’s agroecosystem approach, we argue that these existing theories do not offer such a theoretical framework. The claim of this paper is that a new concept of a farm enterprise as a self-organizing social system, which combines ideas from Actor-Network theory (ANT) and Luhmann’s theory of social systems, can serve as a useful ontological platform for understanding a farm-enterprise as an entity independent of a scientific observer. In this framework, each farm is understood as a self-organizing node in a complex of heterogeneous socio-technical networks of food, supply, knowledge, technology, etc. This implies that a farm has to be understood as the way in which these network relationships are organised by the farm as a self-organizing social system. Among all the different possible ways in which to interact with the surrounding world, the system has to select a coherent strategy in order to make the farming processes possible at all. It will be discussed how this framework may add to the understanding of the continuous development of a heterogeneity of farm strategies and contribute to a more comprehensive view of the fields of regulation and extension

The Critical Point of Conventionally Bred Soft Wheat Varieties in Organic Farming Systems

Nowdays, wheat is the most important crop for organic farming system. However, the varieties breeded and tested in the conditions of organic farming system are still missing. It gives rise to very low level of yield in the Czech Republic (less than 50% of level of convention one in the same conditions). One of the reasons is that the ideotype of organic breeded variety is different from conventional one. The varieties suitable for organic farming system differ in many respects from those adopted in conventional farming. The first difference is obvious from the conventional tests of use value of the varieties, taking just some direct indicators influencing the main parameter (yield) into account. Generally speaking, the features to be tested can be divided into 4 groups: the morphological, the biological, the economic and quality parameters. The conventional varieties are bred in conditions characterised by an abundance of soluble nutrients, and therefore, their root systems are not adapted to an insufficiency of nutrients or weaker bonding of nutrients. The competitiveness to weeds has also been ignored. Any conventional variety, which has never confronted any strong weeds during the breeding process, cannot be assumed to be competitive enough in the conditions of an organic agroecosystem. Resistance to diseases and pests can be similarly characterised. The variety is protected by pesticides throughout the conventional breeding process. Because of the seasonal fluctuations in weather, we need a plastic and flexible variety. They are also different from the point of view of their qualitative parameters

Energy Assessment of Pastoral Dairy Goat Husbandry from an Agroecological Economics Perspective. A Case Study in Andalusia (Spain)

This paper presents a methodological proposal of new energy sustainability indicators according to a novel accounting that follows agroecological and ecological economics criteria. Energy output is reformulated to include manure and thus consider the contribution to fertilization made by pastoral livestock farming to agroecosystems. Energy inputs calculations include the grazing resources. These new definitions and calculations allow for new formulations of the energy return on investment (EROI) as measures of the energy efficiency of livestock farming systems (final EROI and food/feed EROI). The environmental benefit of manure is estimated from the avoided energy cost of using this alternative to inorganic fertilizers (AECM). The environmental benefit of grazing is measured through the energy cost of avoiding cultivated animal feed (AECP) and its impact in terms of non-utilized agricultural area (ALCP). The comparative analysis of different livestock breeding systems in three pastoral dairy goat farms in the Sierra de Cádiz in Andalusia, southern Spain, reveals the analytical potential of the new energy sustainability indicators proposed, as well as the potential environmental benefits derived from territorial-based stockbreeding and, more specifically, grazing activities. Those benefits include gains in energy efficiency, a reduction of the dependence on non-renewable energy, and environmental costs avoided in terms of energy in extensive pastoral systems

Application of processed organic municipal solid waste on agricultural land - a scenario analysis

Source separation, composting and anaerobic digestion, with associated land application, are increasingly being considered as alternative waste management strategies to landfilling and incineration of municipal solid waste (MSW). Environmental life cycle assessments are a useful tool in political decision-making about waste management strategies. However, due to the diversity of processed organic MSW and the situations in which it can be applied, the environmental impacts of land application are very hard to determine by experimental means. In the current study, we used the agroecosystem model Daisy to simulate a range of different scenarios representing different geographical areas, farm and soil types under Danish conditions and legislation. Generally, the application of processed organic MSW resulted in increased emissions compared with the corresponding standard scenarios, but with large differences between scenarios. Emission coefficients for nitrogen leaching to the groundwater ranged from 0.03 to 0.87, while those for nitrogen lost to surface waters through tile drains ranged from 0 to 0.30. Emission coefficients for N2O formation ranged from 0.013 to 0.022 and for ammonia volatilization from 0.016 to 0.11. These estimates are within reasonable range of observed values under similar conditions. Furthermore, a sensitivity analysis showed that the estimates were not very sensitive to the mineralization dynamics of the processed organic MSW. The results show that agroecosystem models can be powerful tools to estimate the environmental impacts of land application of processed MSW under different conditions. Despite this, agroecosystem models have only been used to a very limited degree for this purpose