Vibeke Langer

Innovative Education in Agroecology: Experiential Learning for a Sustainable Agriculture

The transdisciplinary field of agroecology provides a platform for experiential learning based on an expanded vision of research on sustainable farming and food systems and the application of results in creating effective learning landscapes for students. With increased recognition of limitations of fossil fuels, fresh water, and available farmland, educators are changing focus from strategies to reach maximum yields to those that feature resource use efficiency and resilience of production systems in a less benign climate. To help students deal with complexity and uncertainty and a wide range of biological and social dimensions of the food challenge, a whole-systems approach that involves life-cycle analysis and consideration of long-term impacts of systems is essential. Seven educational case studies in the Nordic Region and the U.S. Midwest demonstrate how educators can incorporate theory of the ecology of food systems with the action learning component needed to develop student potentials to create responsible change in society. New roles of agroecology instructors and students are described as they pursue a co-learning strategy to develop and apply technology to assure the productivity and security of future food systems.

Environmental assessment of organic juice imported to Denmark: a case study on oranges ( Citrus sinensis ) from Brazil

Growing global trade with organic products has given rise to a debate on the environmental impacts during both production and transport. Environmental hotspots of organic orange juice produced by smallholders in Brazil, processed and imported to Denmark, were identified in a case study using a life cycle approach. Furthermore, small-scale organic orange production was compared with small-scale conventional and large-scale organic orange production in the case study area in Brazil. Transport was the main contributor (58%) to the global warming potential of organic orange juice from small-scale farmers imported to Denmark, followed by the farm stage (23%), especially the truck transport of fresh oranges in Brazil and of reconstituted orange juice in Europe. Non-renewable energy use per hectare was significantly lower on the organic small-scale farms than on the conventional, with a similar pattern for global warming potential and eutrophication. Including soil carbon sequestration in organic plantations widened the difference in global warming potential between organic and conventional. Organic small-scale farms had a higher crop diversity than conventional, which may have a positive effect on biodiversity along with the spontaneous vegetation between the organic orange trees and the absence of toxic pesticides. Comparing small-scale with large-scale organic orange production, crop diversity was higher on the small-scale farms, while global warming potential, eutrophication potential and the use of copper per hectare were significantly lower, indicating that environmental impacts from small-scale differ from large-scale organic farms.

Energy Use in Organic, Green and Conventional Pear Producing Systems—Cases from China

The objective of this study was to evaluate the differences in the energy consumption between the production of certified organic pear, green food certified pear, and conventional pear in two areas in China. Data were collected from interviews with farmers during 2007 and 2008. Energy inputs were significantly higher in organic systems compared with conventional and green systems. Fertilizer was the most important contributor to energy consumption in all three farming systems. Three calculation methods for energy value of manure have been found in the literature: substitution method, by-product method, and thermal method. The choice of various calculation methods for estimating the energy value of manure turns out to have great influence on the results in terms of energy inputs and energy efficiency. Additionally, energy inputs and energy efficiency were also influenced by other agricultural inputs, such as machinery and corresponding fossil fuels, human labor, etc. Possible explanations for these differences are discussed.

The potential of leys and short rotation coppice hedges as reservoirs for parasitoids of cereal aphids in organic agriculture

The aim of this study was to assess whether leys used for nitrogen fixation and fodder, which cover from a fifth to more than half the acreage on organic farms, as well as short rotation coppice (SRC) used for energy purposes, have potentials as reservoirs for aphid parasitoids in organic agriculture. Exposure of cereal aphids to naturally occurring parasitoids in various crops showed that parasitoids capable of parasitizing the pest aphid Sitobion avenae were active in ley, alfalfa and SRC from spring to late autumn, but in barley fields only in mid-summer. Parasitism by Aphidius sp. dominated in ley, whereas parasitism by Praon sp. was most frequent in SRC. Alternative aphid hosts for parasitoids of S. avenae were shown to be present in late summer, late autumn and early spring in ley and SRC. Within field distribution of parasitism and prevalence of entomophtoralean fungi on aphids in spring barley fields were determined by spatially explicit sampling, but was not consistently affected by proximity to ley or SRC. The data indicate that SRC hedges and clover/grass leys in the rotation may increase diversity and activity of parasitoids attacking cereal aphids.

Energy efficiency of organic pear production in greenhouses in China

The development of organic protected cultivation taking place in densely populated areas has raised the question whether it is an environmentally friendly production system. The present study investigated energy consumption of organic pear production in two production systems, namely in traditional Chinese solar greenhouses and in the open field. In both production systems, energy output/input ratio and energy productivity were used as indicators to determine the energy efficiency; yield, cost of production, net economic return per land area unit and benefit/cost ratio were used to evaluate economic productivity. The analysis results indicated that energy input and energy output per land area unit in the solar greenhouse were higher than in the open field; whereas energy efficiency in terms of output/input ratio and energy productivity were lower in the solar greenhouse than those in the open field. However, if energy input sequestered in the protected structure was excluded in the solar greenhouse production system, energy efficiency was higher in the greenhouse system than in the open-field system. Our analysis further showed that the economic costs, the yield, cost of production, gross product value and net income per land area unit in the greenhouse were more than twice as high as those in the open field due to a higher tree density and a premium price. However, the production taking place in the open field used a great share of renewable energy and higher energy efficiency, which may comply more with the principles of organic farming than the greenhouse production system.

Collaborative partnerships between organic farmers in livestock-intensive areas of Denmark

Specialisation within organic agriculture in many western European countries has led to the decoupling of crop and animal systems, resulting in a shortfall in manure fertilisers on most farms and a surplus on others. One solution to solve a problem has been the establishment of collaborative partnerships between specialist organic farms for manure exchange. The aim of this study is to acquire factual knowledge about existing partnerships. A survey was undertaken of dairy farms in livestock-intensive areas of Denmark, identifying and comparing 95 partnerships between organic dairy farms and organic arable farms with 144 partnerships between conventional dairy farms and conventional arable farms. In order to understand the diversity of strategies among organic farmers, five types of partnerships were identified. The character and functioning of the organic partnerships are influenced by the high demand for organic-certified manure on organic arable farms, but many organic dairy-arable partners also have strong social connections irrespective of the distances involved. The five organic partnership types showed that the organic partners’ strategies were influenced by environmental regulations as well as social connections and location. Trust and reciprocal relationships through high-quality communication and well-functioning institutional arrangements seem to play pivotal roles for partnerships to be maintained. As organic farmers are continuously facing global market conditions and tightening regulations, the development of collaborative partnerships which could contribute to adaptability and flexibility is essential. These findings are not exclusive to organic farmers and may also apply to other intensive livestock regions in Europe.