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971.
ABSTRACT: Water budget studies are essential for water resources and environmental management. In this study, a water budget analysis is presented for the Everglades Agricultural Area (EAA) in South Florida for the period from 1973 to 1991. The EAA is a highly productive irrigation/drainage basin that has a high water table and organic soils. Water quality problems are associated with the drainage discharge from the basin. During dry periods, supplemental water is used for irrigation and in rainy periods excess water with relatively higher phosphorus content is pumped out of the basin to Lake Okeechobee and the Everglades ecosystem. Elevated concentrations of phosphorus in the runoff/drainage that is discharged from the EAA basin have created water quality problems. The mean surface water inflow to the basin was 63,990 ha-m, and the outflow was 131,447 ha-m per year. On the average, supplemental surface water use was 47,411 ha-m, and runoff/drainage was 114,816 ha-m per year. The mean annual basin rainfall was 120.9 cm. A general trend in the decline of the wet season rainfall is observed.  相似文献   
972.
Utilitarian ethics provides a model for evaluating moral responsibility in agricultural research decisions according to the balance of costs and benefits accruing to the public at large. Given the traditions and special requirements of agricultural research planning, utilitarian theory is well adapted to serve as a starting point for evaluating these decisions, but utilitarianism has defects that are well documented in the philosophical literature. Criticisms of research decisions in agricultural mechanization and biotechnology correspond to documented defects in utilitarian theory. Research administrators can expect that application of a utilitarian standard ignoring these deficiencies will become the occasion for predictable attacks by critics. Administrators who are sensitive to the strengths and weaknesses of utilitarian ethics are equipped to make a better allocation of research effort.  相似文献   
973.
ABSTRACT: We tested the common assumption, made when expressing phosphorus export on an areal basis, that this export is a linear function of catchment area and found it wanting. The data show that in agricultural catchments, TP (total phosphorus) export varies as the 0.77 power of drainage basin area, resulting in a reduction in phosphorus delivery per unit area with increasing catchment size. Following further division of catchments according to agricultural practice, we found that this spatial scale effect is restricted to row crops and pastures. We present simple statistical models to allow a comparison of TP export from catchments of different size. Such models are not needed for nonrow crops, mixed agricultural and forested catchments, where TP export is a linear function of catchment size.  相似文献   
974.
ABSTRACT: This paper describes a procedure to design pluvial drainage systems in such a way as to prevent large excavation volumes and erosive velocities. To this end the storage capacity of the channel system is taken into account. In a preliminary step, the procedure employs an approximate method to determine the channel dimensions. Therefore, the dimensions are adjusted by means of a numerical method of solution of the unsteady flow equations. An example is included.  相似文献   
975.
本文分析评价了温州市农业资源,农业开发条件与潜力,提出了农业区域开发的指导思想,总体目标与主要任务,确定了农业商品生产基地,划分了农业开发区,阐述了农业区域开发的对策与措施。  相似文献   
976.
A geoinformation technology for creating spatially distributed greenhouse gas inventories based on a methodology provided by the Intergovernmental Panel on Climate Change and special software linking input data, inventory models, and a means for visualization are proposed. This technology opens up new possibilities for qualitative and quantitative spatially distributed presentations of inventory uncertainty at the regional level. Problems concerning uncertainty and verification of the distributed inventory are discussed. A Monte Carlo analysis of uncertainties in the energy sector at the regional level is performed, and a number of simulations concerning the effectiveness of uncertainty reduction in some regions are carried out. Uncertainties in activity data have a considerable influence on overall inventory uncertainty, for example, the inventory uncertainty in the energy sector declines from 3.2 to 2.0% when the uncertainty of energy-related statistical data on fuels combusted in the energy industries declines from 10 to 5%. Within the energy sector, the ‘energy industries’ subsector has the greatest impact on inventory uncertainty. The relative uncertainty in the energy sector inventory can be reduced from 2.19 to 1.47% if the uncertainty of specific statistical data on fuel consumption decreases from 10 to 5%. The ‘energy industries’ subsector has the greatest influence in the Donetsk oblast. Reducing the uncertainty of statistical data on electricity generation in just three regions – the Donetsk, Dnipropetrovsk, and Luhansk oblasts – from 7.5 to 4.0% results in a decline from 2.6 to 1.6% in the uncertainty in the national energy sector inventory.  相似文献   
977.
农业旅游对发展新农村具有重大的推动作用,已经成为近年来研究的一个热点课题。以国家旅游局命名的359个农业旅游示范点为研究对象,通过对农业旅游示范点的空间分布概况以及分布密度、客源市场空间联系的分析,揭示了农业旅游的空间分布特征,据此对我国目前的农业旅游分区进行了探讨,提出了四大分区的构想。  相似文献   
978.
The challenge of pursuing sustainability in agriculture is often viewed as mainly or wholly technical in nature, requiring the reform of farming methods and the development and adoption of alternative technologies. Likewise, the purpose of sustainability is frequently cast in utilitarian terms, as a means of protecting a valuable resource (i.e., soil) and of satisfying market demands for healthy, tasty food. Paul B. Thompson has argued that the embrace of these views by many in the consumer/environmental movement enables easy co-optation by agribusiness. It also reflects a critical weakness in this movement: a lack of commitment to philosophical principles that depart from the utilitarian premises of the industrial model of agriculture. This paper draws on the writings of Thomas Berry and Liberty Hyde Bailey to identify the philosophical principles of what we call planetary agrarianism. From the perspective of planetary agrarianism, the pursuit of sustainability is a broad and challenging moral, educational, and political task. Berry helps us see that it is fundamentally a project of worldview transition, which requires a new cultural narrative that must rival, in form and appeal, the mythic power of the utilitarian industrial vision. Liberty Hyde Bailey, author of The Holy Earth (1915) and a leader in the land-grant education and nature-study movements, took up the project of worldview transition in his life work. While in some ways dated and flawed, Bailey’s writings are a valuable source of guidance for developing and pursuing a viable philosophy of agriculture for the 21st century.  相似文献   
979.
Annual expenditures by the federal government in the United States for agricultural conservation programs increased about 80 percent with passage of the 2002 Farm Bill. However, environmental benefits of these programs have not been quantified. A national project is under way to estimate the effect of conservation practices on environmental resources. The watershed models intended for use in that project are focused on water quantity and quality and have minimal habitat assessment capability. Major impairments to aquatic ecosystems in many watersheds consist of physical habitat degradation, not water quality, suggesting that current models for this national initiative do not address one of the most significant aspects of aquatic ecosystem degradation. Currently used models contain some components relevant to aquatic habitat, and this paper describes specific components that should be added to allow rudimentary stream habitat quality assessments. At least six types of variables could be examined for ecological impact: land use, streamflow, water temperature, streambed material type, large woody debris, and hydraulic conditions at base flow. All of these variables are influenced by the presence, location, and quality of buffers. Generation of stream corridor ecological or habitat quality indices might contribute to assessments of the success or failure of conservation programs. Additional research is needed to refine procedures for combining specific measures of stream habitat into ecologically meaningful indices.  相似文献   
980.
农业灾害统计是认识和分析农业灾害问题的主要环节,做好这一工作对于实现我国农业可持续发展具有重要意义。文章在分析我国农业灾害统计存在问题的基础上,指出在新时期为推进我国农业灾害统计工作,必须大力加强农业灾害统计指标体系的构建和统计规范性的建立,改进传统的农业灾害统计方法、流程,并完善农业灾害统计管理等工作。  相似文献   
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