EVALUATION OF MANAGEMENT PRACTICES TO CONTROL AGRICULTURAL POLLUTANTS1

ABSTRACT: The objective of this study was to evaluate the effectiveness of various land-use practices upon the production of nonpoint source pollutants from small agricultural watersheds in Northern Virginia. Pollutant production at each watershed was determined by individual monitoring stations. Data analysis consisted of a determination of the site specific pollutant yield for similar watersheds subjected to differing crop management approaches. These collected data were then compared to those generated by a parametric, event model developed for this investigation. This synthetic data base was used to eliminate or reduce errors resulting from monitoring site differences and to extend the collected data for additional comparisons.     

POLICY IMPACTS ON AGRICULTURAL IRRIGATION ELECTRICITY DEMAND IN THE COLUMBIA BASIN1

ABSTRACT: Accurately estimating the price elasticity of demand for irrigation electricity is important to major electricity suppliers such as the Bonneville Power Administration (BPA) of the Pacific Northwest. The BPA has a revenue maximization objective, and the elasticity of demand is central to its rate setting process. Several studies have attempted to estimate demand for irrigation electricity, but none has explicitly included federal agricultural policy and program variables. Tins paper discusses how agricultural programs may influence farmers irrigation decisions and thus their demand for irrigation electricity. It suggests that existing programs serve to make farmers more responsive to electricity rate increases than would otherwise be the case. Thus, studies that fail to include them may underestimate the responsiveness of farmers to electricity rate increases.     

攀西地区农业开发条件、潜力与对策

攀西地区位于四川省的西南部,包括攀枝花市和凉山州的全部。幅员面积6.75万km~2,1988年末人口为437.3万人。攀西不仅矿产、水能资源举世瞩目,而且光热资源丰富,宜农荒地资源多,农业开发条件好、潜力大,是国家原材料、能源和农业开发的重点地区。本文拟就种植业为重点,对攀西农业开发条件、潜力和对策进行分析论证,以引起社会重视,使之尽快列为全国农业开发的重点区,进行先期开发。     

AN ARCHETYPAL LINEAR PROGRAMMING MODEL FOR OPTIMAL INTERTEMPORAL ALLOCATION OF GROUNDWATR TO AGRICULTURAL ACTIVITIES1

ABSTRACT: In the past, researchers have applied a variety of analytical techniques for maximizing the present value of a stock resource - simulation, calculus of variations, stochastic dynamic programming, and optimal control theory. This paper presents a more operational approach - linear programming. A simplified, broadly drawn example from Southwest agriculture is used for demonstrating the model's structure and output. The method is based on a set of state transformation operations that prevent the additivity assumption of linear programming from being violated.     

A CONCEPTUAL FRAMEWORK FOR EVALUATING AGRICULTURAL WATER CONSERVATION POTENTIALS1

ABSTRACT: This paper defines types of water losses in irrigated agriculture and outlines potentials for water conservation. Recoverable water “losses” (seepage, leakage, and spillage during storage and conveyance, and surface runoff and deep percolation during irrigation) and irrecoverable losses (evaporation from water and soil surfaces and transpiration from plants) are described and illustrated. Some conservation terms are defined, particularly the distinction between on-farm irrigation efficiency and areawide efficiency. Briefly reviewed are agricultural water conservation technologies and their applicability. The biggest untapped potential for water conservation may be a reduction in irrecoverable losses, especially evapotranspiration. The advantages and disadvantages of reducing recoverable and irrecoverable water losses are described, including possible effects on ground water, energy, salinity, crops, wildlife, and in-stream uses. Such information may be useful in several policy and management issues, e.g., ground water overdraft and possible constraints on crops and sites to be irrigated.     

DEVELOPMENT AND EVALUATION OF A DIMENSIONLESS UNIT HYDROGRAPH1

ABSTRACT: A generalized unit hydrograph method is developed and evaluated for ungaged watersheds. A key component in this method is the value of a dimensionless storage coefficient. Procedures to estimate this coefficient are given using calibrated values from 142 rainfall-runoff events gaged in watershed located mainly in the Eastern US. Only limited success was obtained in predicting this storage coefficient. Thirty-seven, independent rainfall-runoff events were used to test the proposed technique. The generalized unit hydrograph predicted the observed runoff hydrographs fairly well with considerable improvement in accuracy over the SCS dimensionless unit hydrograph. Approximately one-half of test storms had percent errors in predicted peak flow rates that were less than 34 percent compared to percent error of 88 percent with the SCS method.     

脱硫石膏农业利用研究进展与展望

概述火电厂脱硫石膏定义、生产过程和性质。简述了脱离石膏的工业利用，详述了脱离石膏对酸性和碱性土壤改良的现状和机理，并展望了脱硫石膏促进滩涂土植被演替的前景。     

能量生态学在农业生态系统研究中的应用──胜利油田生态农场能量流分析

本文以能量生态学原理为指导，应用投入产出法对胜利油田生态农场系统内能量流动及能量利用效率进行了计算分析，从中发现了系统生产的薄弱环节和在能量利用方面的问题，并提出了调整系统内部产业结构和能量投入结构的措施，为今后系统生产力及能量转化效率的提高，提供了科学依据。     

中国农产品产地环境标准中存在的问题与对策研究

目前中国已经颁布的各类产地环境类标准已超过30多个(不含地方标准)，与欧美发达国家同类标准相比，中国现行的产地环境类标准普遍存在着制定程序不严谨、相关标准之间衔接统一不够、标准的科学技术水平不高、标准的针对性与实用性不强、标准与分析检验方法不配套等共同的问题。通过实例和数据，对以上问题进行了研究和分析，提出了改革现行的标准管理模式、加强基础性科学研究、借鉴和引进国际先进标准、培育专业技术队伍等对策措施。     

富水农业植物废物的易降解性及对其他堆肥植物降解的影响

对富水型农业植物废物和其他典型城市植物固废进行了好氧堆肥实验．结果表明，富水型农业植物废物的有机质降解率最高，达到了69％．富水型农业植物废物和其他植物固废混合堆肥时能明显提高其他植物固废的降解率．富水型农业植物废物和其他典型城市植物固废混合物的质量比为2：1时，最高降解率39．1％．研究发现这与它们的组分有关，富水型农业植物含水率高达80％以上，含有的有机物质主要为易降解的蛋白质、脂肪、纤维和其他碳水化合物，C／N比在10：1～35：1之间．在堆肥物料中加入富水型农业植物废物可使堆肥的腐熟期缩短至20d，最低C／N比为18．5：1．图4表2参21