Agroecology is the application of ecological concepts and principles to the design and management of sustainable agricultural
systems. An agroecological approach to agriculture has special importance in the humid tropics where agricultural development
and the preservation of tropical forests are most often in direct conflict. It is proposed that a more sustainable approach
to development is needed, where agroecosystems depend on low external inputs, function more on the use of locally available
and renewable resources, have benign impacts on the environment, and are based on the knowledge and culture of the local inhabitants.
Examples of traditional agroecosystem management in Mesoamerica that can provide this basis are presented. The preservation
of both biological and cultural diversity are integral to the long-term sustainable management of natural resources in the
tropics. 相似文献
Burning fossil fuel in the North American continent contributes more to the CO2 global warming problem than in any other continent. The resulting climate changes are expected to alter food production. The overall changes in temperature, moisture, carbon dioxide, insect pests, plant pathogens, and weeds associated with global warming are projected to reduce food production in North America. However, in Africa, the projected slight rise in rainfall is encouraging, especially since Africa already suffers from severe shortages of rainfall. For all regions, a reduction in fossil fuel burning is vital. Adoption of sound ecological resource management, especially soil and water conservation and the prevention of deforestation, is important. Together, these steps will benefit agriculture, the environment, farmers, and society as a whole. 相似文献
Process hazards review (PHR) techniques have generally been applied by large, sophisticated companies in the nuclear, aerospace, and chemical process industries. There remains, however, a large population of smaller distributors and consumers of hazardous materials which could benefit equally from the application of PHR. These consumers unfortunately are generally less sophisticated and individually lack the necessary resources required to apply such state-of-the-art safety techniques.
Where common processes can be identified, it is possible to conduct a more generic PHR that will provide a sound technical basis for recognizing and preventing the development of hazards wherever these processes are used. Some facility-specific issues will always need to be considered, but the existence of the generic PHR should make the conduct of a PHR by each facility considerably easier and less costly.
Researchers from the National Institute for Occupational Safety and Health (NIOSH) contracted with DNV Technica Inc. to lead a hazard and operability study (HAZOP) of agricultural handling of anhydrous ammonia, from the receipt of ammonia at the retail distribution centre to the application of the ammonia by farmers to the fields. The multidisciplinary HAZOP team consisted of representatives from NIOSH, an agricultural chemical trade association, an ammonia producer, state ammonia facility inspectors, a retail distributor, and an equipment manufacturer. Several participants were part-time farmers with ammonia application experience.
Some specific aspects of applying the HAZOP technique in the context of this study, the findings obtained, and the plans to disseminate the important safety information developed during the course of the PHR are discussed. Finally, it is suggested that this approach could prove to be a useful addition to the product stewardship activities of chemical producers. 相似文献
According to the United Nations Framework Convention on Climate Change (UNFCCC) and Kyoto Protocol under it, industrial countries
have to estimate their greenhouse gas emissions annually, and assess the uncertainties in these estimates. In Finland, agricultural
methane (CH4) and nitrous oxide (N2O) emissions represent 7% of anthropogenic greenhouse gas emissions, and globally the share is much higher. Agriculture is
one of the most uncertain emission categories (representing over 20% of greenhouse gas inventory uncertainty in Finland),
due to both high natural variability of the emission sources and poor knowledge of the emission-generating processes. In this
paper, we present an uncertainty estimate of agricultural CH4 and N2O emissions from Finland in 2002. Uncertainties were estimated based on measurement data, literature and expert judgement,
and total uncertainty in agriculture was calculated using Monte Carlo simulation. According to the calculations, agricultural
CH4 and N2O emissions from Finland were 3.7 to 7.8 Tg carbon dioxide (CO2) equivalents, 5.4 Tg being the mean value.Estimates of CH4 emissions are more reliable than those of N2O. N2O from agricultural soils was the most uncertain emission category, and the uncertainty was not reduced by using available
national measurement data of N2O fluxes. Sensitivity study revealed that the uncertainty in total agricultural inventory could be 7% points lower, if more
accurate emission estimation methods were used, including 1) improved data collection in area estimates of organic soils,
2) climate-specific methods for N2O from agricultural soils as already presented in literature, and 3) more detailed CH4 estimation methods for enteric fermentation which can be achieved by investigating national circumstances and digestible
systems of animals in more detail. 相似文献
The ongoing drought in the Sahel region of West Africa highlights the vulnerability of food-producing systems to climate change
and variability. Adaptation to climate should therefore increase the sustainability of agriculture under a long-term drought.
Progress towards sustainability and adaptation in the the Senegal River Basin is hampered by an existing set of social and
ecological relationships that define the control over the means of production and how people interact with their environment.
These relationships are sensitive to the technological inputs and the administration of food production, or the factor bias
in the different policy alternatives for rural development. One option is based on state-controlled, irrigated plantations
to provide rice (Oryza) for the capital, Dakar. This policy emphasizes a top-down management approach, mechanized agriculture and a reliance on
external inputs which strengthens the relationships introduced during the colonial period.
A time series decomposition of the annual flow in the Senegal River at Bakel in Senegal suggests that water resources availability
has been substantially curtailed since 1960, and a review of the water resources budget or availability in the basin suggests
that this policy's food production system is not sustainable under the current climate of the basin. Under these conditions,
this program is exacerbating existing problems of landscape degradation and desertification, which increases rural poverty.
A natural resource management policy offers two adaptation strategies that favour decentralized management and a reduction
of external inputs. The first alternative, “Les Perimetres Irrigués”, emphasizes village-scale irrigation, low water consumption
cereal crops and traditional socio-political structures. The second alternative emphasizes farm-level irrigation and agro-forestry
projects to redress the primary effects of desertification. 相似文献