计量经济分析 = Econometric analysis

Statistics for Spatial Data.

1. Introduction and Overview. 2. Detecting Influential Observations and Outliers. 3. Detecting and Assessing Collinearity. 4. Applications and Remedies. 5. Research Issues and Directions for Extensions. Bibliography. Author Index. Subject Index.

Regression Diagnostics: Identifying Influential Data and Sources of Collinearity

The author systematically examines one of the important issues of information — establishing the market price. He introduces the concept of «search» — where a buyer wanting to get a better price, is forced to question sellers. The article deals with various aspects of finding the necessary information.

Economics of Information

Nitrogen is the most limiting nutrient for crop production in many of the world's agricultural areas and its efficient use is important for the economic sustainability of cropping systems Furthermore, the dynamic nature of N and its propensity for loss from soil‐plant systems creates a unique and challenging environment for its efficient management Crop response to applied N and use efficiency are important criteria for evaluating crop N requirements for maximum economic yield Recovery of N in crop plants is usually less than 50% worldwide Low recovery of N in annual crop is associated with its loss by volatilization, leaching, surface runoff, denitrification, and plant canopy Low recovery of N is not only responsible for higher cost of crop production, but also for environmental pollution Hence, improving N use efficiency (NUE) is desirable to improve crop yields, reducing cost of production, and maintaining environmental quality To improve N efficiency in agriculture, integrated N management strategies that take into consideration improved fertilizer along with soil and crop management practices are necessary Including livestock production with cropping offers one of the best opportunities to improve NUE Synchrony of N supply with crop demand is essential in order to ensure adequate quantity of uptake and utilization and optimum yield This paper discusses N dynamics in soil‐plant systems, and outlines management options for enhancing N use by annual crops

Enhancing nitrogen use efficiency in crop plants

Microbiological Procedures for the Diagnosis of Bovine Udder Infection and Determination of Milk Quality

Spatial analysis of the amenity value of green open space

Probit analysis identified factors that influence the adoption of precision farming technologies by Southeastern cotton farmers. Younger, more educated farmers who operated larger farms and were optimistic about the future of precision farming were most likely to adopt site-specific information technology. The probability of adopting variable-rate input application technology was higher for younger farmers who operated larger farms, owned more of the land they farmed, were more informed about the costs and benefits of precision farming, and were optimistic about the future of precision farming. Computer use was not important, possibly because custom hiring shifts the burden of computer use to agribusiness firms.

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Adoption of Site-Specific Information and Variable-Rate Technologies in Cotton Precision Farming

The Energy Policy Act of 2005 includes a provision designed to double the production and use of ethanol in fuels by 2012, and to ensure that by 2013, a minimum of 250 million gallons per year of ethanol is produced from cellulosic sources, such as corn stover, wheat straw, and switchgrass. Cellulosic ethanol (CE) has a much greater potential volume than grainbased ethanol. For example, if the entire 2005 U.S. corn crop of 11.1 billion bushels had been converted to ethanol, the resulting product would have contained less than 9% of the en-

Challenges to the Development of a Dedicated Energy Crop

Research on how land suitability affects yields and breakeven prices for switchgrass (Panicum virgatum L.) grown as a bioenergy crop is lacking for the U.S. Southeast. Data from a 3-yr multilocation experiment at Milan, TN, were analyzed to determine the influence of soil drainage and landscape position on switchgrass yield and farm-gate breakeven price. Plots were seeded in 2004 with 'Alamo' at 2.8, 5.6, 8.4, 11.2, and 14.0 kg ha -1 pure live seed (PLS). Plots were split in 2005 and N was applied at 0, 67, 134, and 201 kg N ha -1 Farm-gate breakeven prices for 5- and 10-yr production contracts were determined by calculating unit production costs from enterprise budgets that varied by input level and yield. Maximum yields occurred at 67 kg N ha -1 on well-drained soils and at higher N levels on less-well-drained soils. Yield response to seeding rate (SR) was insignificant or small relative to other factors. Averaged across treatments, the well-drained upland location suitable for row crops had the largest yield (17.7 Mg ha -1 ) and lowest breakeven price ($46 Mg -1 ) for a 10-yr period. In contrast, the poorly drained flood plain location considered marginal yielded lowest (8.5 Mg ha -1 ) and had the highest breakeven price ($69 Mg -1 ). Breakeven prices were sensitive to yield, N price, and fuel price. Results suggest a lower breakeven price for switchgrass in the U.S. Southeast as compared with other U.S. regions, mainly due to high yields for the Alamo variety.

Roland K. Roberts

Papers

Microbiological Procedures for the Diagnosis of Bovine Udder Infection and Determination of Milk Quality

Spatial analysis of the amenity value of green open space

Adoption of Site-Specific Information and Variable-Rate Technologies in Cotton Precision Farming

Challenges to the Development of a Dedicated Energy Crop

Yield and Breakeven Price of ‘Alamo’ Switchgrass for Biofuels in Tennessee