辽宁农业灌溉用水影响因素时空差异性研究

目的 文章基于2000—2019年辽宁农业灌溉用水相关数据，将农业灌溉用水压力、效率、用水价格、种植结构等因素纳入农业灌溉用水需求模型，估计各影响因素对农业灌溉用水需求的影响，更好地保障粮食和水资源安全。方法 利用时空地理加权回归模型研究辽宁各地级市农业灌溉用水影响因素作用的时空差异性。结果 （1）不考虑影响因素作用的时空差异性，用水价格和农村居民人均收入变动对辽宁农业灌溉用水需求的影响特别小。（2）考虑到影响因素作用的时空差异性，除了朝阳和大连，其余各地级市农业灌溉用水需求的价格弹性在2014年前后呈现出负向增大的态势，水价改革还有较大的效力空间。（3）辽宁农业灌溉用水效率和种植结构的回归系数在空间上呈现出中部低，四周高的特点。（4）城镇化程度对农业灌溉用水需求的影响呈现出由东北向西南逐渐递减，由正向较强逐渐向负向较强的演变。结论 依据辽宁农业灌溉用水的各影响因素的作用强度，种植结构、用水效率和城镇化程度是影响辽宁农业灌溉用水需求的主要因素，合理制定城镇化规划对该因素回归系数呈显著上升趋势的地级市尤为重要。     

LINEAR PROGRAMMING MODELS FOR DETERMINING IRRIGATION DEMAND FOR WATER*

The purpose of the paper is to discuss linear programming models useful in estimating irrigation demand for water. The discussion is limited to technique and first reviews the general characteristics of linear programming models. The author then goes on to indicate the results of several models developed at the University of Manitoba to estimate irrigation demand. Cet article a pour dessein de discuter des modèles de programmation linéaire qui seraient utiles pour eslimer la demande ?eau pour ?irrigation. La discussion est limitée a la méthode à suivre et revolt en lout premier lieu les caractéristiques généraux des modèles de programmation lineaire. Linéaire continue alors avec une analyse des résultats de plusieurs modèles pour eslimer la demande ?eau pour ?irrigation développés à?Université Manitoba.     

陕西省农业灌溉水资源保障程度及空间差异分析

[目的]文章选取2016年陕西省各市区农业灌溉水资源相关数据,分析其对粮食生产的影响,进而计算出陕西省及其各市区农业灌溉水资源对粮食生产保障程度,最终总结其存在的空间差异,并提出差异化的解决措施,以保障陕西省粮食安全。[方法]选用农业灌溉水资源保障度分析模型,针对陕西省各市区的水资源供需情况、粮食种植结构及产量和农作物灌溉情况,对陕西省及其各市区的农业灌溉水资源保障程度进行计算,研究其空间差异性。[结果]陕西省农业灌溉水资源保障度为101.84%,基本上能满足农业灌溉用水需求,但已迫近水资源供给紧张的边缘。陕西省农业灌溉水资源保障度呈显著的空间差异,关中地区农业灌溉水资源保障度P为82.20%,农业灌溉水资源轻度缺乏,属于资源型缺水现象;陕北地区农业灌溉水资源保障P为112.38%,影响该地区农业生产发展;陕南地区农业灌溉水资源保障P为145.92%,农业灌溉水资源丰富,灌溉耕地能够得到用水保障。[结论]农业灌溉水资源对粮食生产具有重要的作用,陕西省农业灌溉用水资源存在较大的空间差异性,需要参考不同地区的农业灌溉水资源保障度数值,采取不同的节水策略,以保障粮食安全生产。     

ECONOMIC OPTIMISATION OF SPRINKLER IRRIGATION CONSIDERING UNCERTAINTY OF SPATIAL WATER DISTRIBUTION*

The study is focused on the development and the application of a stochastic economic optimisation model by which optimal levels of applied water and sprinkler spacing are determined. Data on crop-water production function and uniformity of water application are taken from a sprinkler irrigation plot of sweet corn. It was found that a saving of irrigation water can be achieved not only by raising water prices but also by increasing application uniformity.     

DEVELOPMENT AND ANALYSIS OF INPUT-OUTPUT RELATIONS FOR IRRIGATION WATER

Recent developments in climatology mean that economists now have a highly acceptable physical theory which can underlie their analysis of the economic aspects of water as an input to the production process, as a source of production instability, and as a major component of error in their estimated crop production functions. This paper presents a model and a procedure for synthesising and analysing irrigation water crop input output relations based on this theory. The importance of time of application of water as well as quantity is shown. Different frequencies of irrigation are optimal at different times of the growing season.     

塔里木灌区农业可持续发展对策

塔里木灌区地处暖温带，光热资源丰富，具有发展农业的良好条件。近年来，灌区大规模农业综合开发，农业经济得到了较快的发展，但也面临着许多资源和环境问题。针对塔里木灌区的农业环境现状，提出了强化农业综合开发力度，加速优势资源转化，调整农业产业结构，合理作物布局，充分高效利用水资源，建立发展生态农业，积极发展高新技术产业，加强农业生态环境保护，防止环境污染，维持灌区生态平衡，树立广大群众的资源价值观，提高全民环保意识等促进灌区农业可持续发展的对策。     

Irrigation water productivity in Cambodian rice systems

Knowledge of the marginal productivity of water is crucial for decisions about its allocation between uses, which is particularly important in the context of increasing competition for water. Using primary, plot‐level panel data, this article estimates the marginal productivity of water from supplementary irrigation in lowland rice systems in Cambodia, taking into account farmer and plot heterogeneity as well as self‐selection of supplementary irrigation. Our estimates indicate a range of elasticities for rice output with respect to water inputs of between 0.057 and 0.069 for wet season production, substantially lower than previous estimates based on either aggregate or trial data. We discuss the policy implications of these results, in particular with respect to the utility of demand management policies and the challenges they pose to the decentralization of water management to Farmer Water Users Groups.     

基于遥感蒸散数据的农田灌溉水平评价和设施建设分区研究

[目的]利用遥感蒸散数据快速评价农田年度灌溉水平,及时获取基本农田建设成效,为农田灌溉设施分区建设提供参考。[方法]以黑龙江省海伦市为研究区,MOD16蒸散产品为数据源,计算有效灌溉量、灌溉需水量和作物缺水指数,分别对研究区2013年的旱地和水田灌溉水平进行评价,并将评价结果与农田水利设施作用分值图进行叠加分析,在此基础上进行基本农田灌溉设施建设分区。[结果]2013年海伦市耕地灌溉水平整体较高,区域间建设水平差别较大,可划分为4个级别。其中1级和2级灌溉水平的地块面积比例可达78.06%,地域分布上看,北部、西部、中部乡镇灌溉水平较高,东南部乡镇灌溉水平相对较低。叠加得出8种组合类型,分为设施修建型、设施提升型和设施维护型3种分区类型。[结论]研究为高标准农田建设提供了更详细的农田灌溉水平评价方法和更具差别化的农田灌溉设施建设策略。     

The positive impacts of irrigation schedules on rice yield and water consumption: synergies in Jilin Province,Northeast China

Food and water security in China are inextricably linked to the development of regional economy, especially for regions with temporary or sustained water shortage such as Jilin Province in northeast China. Water-saving irrigation practices are therefore urgently sought to maintain sustainable growth in grain production. To improve knowledge of the effect of irrigation water level on rice yield and water-use efficiency (WUE), we conducted a field experimental study over two growing seasons in central Jilin. The irrigation experiment included four schedules: (1) traditional irrigation (CK), (2) shallow wet irrigation (T1), (3) intermittent irrigation (T2), and (4) controlled irrigation (T3). Soil test pits were used to estimate evapotranspiration and seepage. The study showed that T3 had the highest WUE (1.64?kg/m³). However, the highest rice yield was found in T1 (9867?kg/ha¹) that achieved the second highest WUE (1.63?kg/m³). Compared with CK, T1 and T3 consumed 7.3% and 36.1% less water, respectively. If adopted at the operational scale, these two schedules could help reduce the pressure of local surface water supply and the production costs significantly. The results gained from this study could also have relevant implication in developing an effective irrigation management for other high-latitude regions.     

景电灌区绿洲生态农业可持续发展对策研究

景电灌区位于甘肃省北部景泰和古浪境内,该文在研究灌区农业资源现状的基础上,分析了灌区绿洲生态农业可持续发展面临的主要问题,提出了以节水灌溉为重点,优化灌区作物种植结构,大力发展优势主导产业,加强生态环境的综合治理等绿洲生态农业可持续发展应当采取的主要措施。     

ESTIMATION OF EFFECTIVE RISK REDUCION THROUGH IRRIGATION OF A PERENIAL CROP*

This paper outlines an approach to assessing the benefits from in vestment in the irrigation of tea stands in three areas of East Pakistan. Irrigation aflects both the establishment and productive life of the growing crop, and therefore the analysis includes a discounred assessment of the replacement decision, as well as an appraisal of the change in technology. Since the biological and weather eflects that determine annual and long-run productivity of the stand are stochastic variables, the evaluation is made using a simulation model in which these determinants are introduced as known discrete probabilities. Using this model an estimate may be made of rhe net gains to a tea estate of the risk reduction achieved by eliminating harmful crop moisture deficits.     

水肥一体化技术的环境效应与经济效应分析——基于山东省苹果种植户的调研数据

目的 绿色农业技术的环境与经济收益核算,对于推进技术应用、解决农业面源污染问题和实现生态文明建设具有重要的参考价值。究竟绿色农业技术有没有顺利实现农户的经济目标与社会的环境目标？现有研究诸多争议与困惑。方法 文章以水肥一体化技术为例,基于山东省649份苹果种植户的实地调查数据,借助内生转换模型,从微观层面探讨了水肥一体化技术的环境效应和经济效应。结果 （1）总体来看,农户采纳水肥一体化技术实现了节肥增收的目的。（2）采纳水肥一体化技术后,样本农户能够节约化肥施用量11.79%~20.98%,提高农产品收入8.15%~9.07%。（3）不同规模农户采纳水肥一体化技术的节肥增收效应存在显著差异。对于采纳水肥一体化技术的规模户而言,其化肥减量作用强度明显高于小规模农户。与此同时,采纳水肥一体化技术只对规模户有明显的农产品增收作用。结论 注重完善市场流通机制下农产品质量监督体系,使绿色农产品能够获得质量溢价的收益。同时创建有利于水肥一体化技术推广应用的土地规模条件,获得规模化带来的节肥增收效应。推动外部性内部化补偿制度实施,政府对具有正外部性行为的农户给予补偿。     

超量灌溉对农田耕作区水土肥流失的影响

目前,对山区、丘陵区的水土流失情况及治理措施,已有相对成熟的研究,但对于平原农田耕作区的水、土、肥的流失与治理,则少见有研究资料与科研成果发布。而平原农田耕作区在暴雨或高强度灌水情况下,极易造成土壤水、土、肥的流失。文章针对上述情况,选取具有代表性的沧州枣粮间作地中壤质土作为试验材料,模拟不同降雨强度与施肥量下,土壤经水流冲刷后,观察水、土、肥的流失规律。通过模拟天然降雨过程,对土壤中水、土、肥流失的影响,探索出平原农田耕作区治理水土流失的一般规律,并提出保护地表免受雨滴打击、加大表层土壤贮水量等提高土壤入渗性能的治理措施。     

A MODEL FOR THE ECONOMIC EVALUATION OF WATER QUALITY IN IRRIGATION

A model for determination of the efficient combination of water quantity and quality (salinity) in irrigation is presented. The efficient combination is evaluated with respect to a predetermined threshold salt concentration in the soil solution. A leaching model, designed for tracing salt distribution in the soil profile, serves as the basis for the analysis. The optimal quantity-quality combinations are derived with the aid of a linear programming model. An illustrative application of the model concludes the presentation.     

农业水价形成机制的建构与检验以四川武引灌区为例

[目的]以四川武引灌区为案例，实证检验农业水价现实运行情况与农业水价形成机制的契合程度，探讨优化农业水价形成机制的基本方向。[方法]文章从市场和政府两个维度分析农业水价影响因素，建构“成本导向、支付可行”的农业水价形成机制，科学测定农业水价的弹性区间。[结果]市场作用下，供给维度要以供水工程成本为基准，需求维度在用水户承载力支付能力区间较为合理；由于农业用水具有正外部性以及农业供水的垄断性，政府应为农业用水构建合理的价格机制。农业水价构成应以平均运行可变成本为最低参考标准，也可实行全成本农业水价，以此符合“成本导向”。“支付可行”表现为实际支付能力和心理支付意愿，农业水价既要考虑农业生产中投入产出情况，判断用水户实际支付能力，又要研究其心理支付意愿，分析现实情况和心理参照点的差别情况。[结论]农业水价形成机制的学理建构与现实运行具有内在逻辑一致性，优化农业水价形成机制重点包括两个方面，即优化“成本导向”形成机制，科学建立灌区成本核算体系，完善农业用水价格制定准则，确立农业用水计收方式。优化“支付可行”形成机制，积极促进用水户增收，提高水价实际支付能力，强化宣传提高用水户心里支付意愿及加...     

Comparing Open-Ended Choice Experiments and Experimental Auctions: An Application to Golden Rice

We use two experimental valuation methods to estimate consumer demand for genetically modified golden rice. The first is an open-ended choice experiment (OECE) where participants name the quantities of golden rice and conventional rice demanded at each of several price combinations, one of which will be randomly chosen as binding. This allows us to estimate market demand by aggregating demand across participants. This estimate of market demand also allows us to estimate own-price elasticity and consumer surplus for golden rice. Comparing willingness-to-pay (WTP) estimates from the OECE with those from a uniform-price auction, we find that OECE WTP estimates exhibit less affiliation across rounds, and the effects of positive and negative information under the OECE are more consistent with prior expectations and existing studies. We also find that, while auction WTP estimates more than double across five rounds, OECE WTP estimates are stable across rounds and are always roughly equal to those from the final auction round.     

Irrigation production functions with water-capital substitution

The dynamics of biomass growth implies that the yield of irrigated crops depends, in addition to the total amount of water applied, on irrigation scheduling during the growing period. Advanced irrigation technologies relax constraints on irrigation rates and timing, allowing us to better adjust irrigation scheduling to the varying needs of the plants along the growing period. Irrigation production functions, then, should include capital (or expenditures on irrigation equipment) in addition to aggregate water. We derive such functions and study their water-capital substitution properties. Implications for water demand and adoption of irrigation technologies are investigated. A numerical example illustrates these properties.     

FORECASTING THE FUTURE FOR TIMBER*

For each State a simple two-equation model of demand and supply was fitted to post-war data using two-stage least squares. Prior estimates of the housing coefficient were used to break collinearity problems in the demand function. Price elasticity of demand appears to be high and income elasticity moderate but declining with increasing income. The use of these estimates in forecasting is briefly outlined.     

Private irrigation investment in Colombia: effects of violence,macroeconomic policy,and environmental conditions

This paper identifies and estimates the effects of several determinant, on private investment in irrigation in Colombia. It attempts to quantify macroeconomic policy, environment, and violence variables that have been identified in previous studies as significantly affecting investment, in agriculture in genera., and in irrigation in particular. Variables such as violence, climate, and governmental price credit policies are used to explain changes in private investment in irrigation across regions and over time. Violence negatively affects private investment. Climate affects the investment such that in regions with favorable climate condition, investment in irrigation is less attractive, and appropriate government crop-price and credit policies promote investment in irrigation.     

Variability in wheat export demand elasticity: Policy implications

Agricultural economists and policy makers in the United States believe that the magnitude of the export demand elasticity is one of the most important parameters used in farm policy decisions. However, past empirical estimates show wide variation in the size of the U.S. export demand elasticity. Reasons for this wide variation go beyond differences in model specification, estimation methods, and period of estimation to involve factors such as trade policies and changes in the supply and demand conditions of foreign countries. In view of the continual variation in magnitude, the elasticity of export demand should be viewed as a variable rather than as a parameter. In this study, U.S. wheat export demand elasticities are computed using a world wheat trade model. The estimates show that the elasticities vary significantly over time. They also reveal that elimination of trade barriers would more than double wheat export demand elasticities.