塔里木河流域基于资源环境水价的农业水价的承受力分析

首先在成本水价基础上,分别构建塔河流域作物和流域基于水资源费的未来农业水价,然后进一步汇总和计算了塔河流域农户对基于资源环境水价的未来农业水价的承受力分析的基本指标;在此基础上,分析了塔河流域农户对基于资源环境水价的未来农业水价的承受力,主要结果表明：除叶尔羌河、和田河流域和干流下游基于资源环境水价的未来流域和作物水价的农户承受力超过适宜经济承受力外,其它源流和干流上中游的农户水价承受力则处于适宜经济承受力范围,未来塔河流域应当实行差别水价政策;干流下游、叶尔羌河流域未来农业水价承受力很低,尤其是流域未来粮食作物水价的承受力很低,必须给予粮食作物农业水价直接补偿。而且,环境水价对农户水价承受力影响较小,能够成为未来流域生态环境保护的主要经济手段。     

基于资源环境水价的塔里木河流域作物农业水价的节水效应分析

立足当前塔河流域的成本水价,基于已有研究的流域水资源费和环境水价模型与相关资料,首先构建了流域基于资源环境水价的未来农业水价;然后,利用已有研究资料和流域不同作物的水分生产函数,进一步构建了流域未来作物农业水价的需求效应模型;分析了未来塔河流域基于资源环境水价的未来作物农业水价的节水效应。结果表明:基于资源环境水价的未来农业水价调整可大幅提高节水效应,只是环境水价更侧重于实现流域生态用水保障的经济补偿。再者,不同流域和作物水价需求弹性效应差别很大,可以实行有差别的农业水价调整政策。还有,流域水价弹性系数会由缺乏弹性变为富有弹性,受作物基本灌溉定额限制,就是采用高效节水技术也难以保证水价节水效应的实现,这成为流域农业水价调整可行性的一个标志。但是,这也使未来流域农业水价的需求效应分析事关流域粮食安全和用水户的水价承受力问题,成为未来塔河流域农业水价调整研究的重要相关研究内容。     

Impact of irrigation timing on simulated water-crop production functions

Estimates of the effects of alternative discrete irrigation water scheduling options on consumptive use or evapotranspiration and on crop yield are developed for a northeastern Colorado case study. The analysis proceeds from the premise that farmers, rather than considering irrigation water as a continuously variable input, tend to treat irrigations as discrete events, and make scheduling decisions as choices among numbers of irrigations of approximately equal volume. The van Genuchten-Hanks model is employed to develop a transient-state water-crop production function model. Results for two crops – corn grain and edible dry beans – are presented here. Findings are that the effect of the number of irrigations on evapotranspiration and yield per hectare varies widely, depending upon the timing of applications. When farmers can choose the optimal timing of irrigations, a reduced number of irrigations has a relatively limited adverse effect on crop production until irrigations are reduced to less than four per season. However, there are many situations in which an inability to apply water can result in a very large reduction from potential maximum yield, particularly if water is withheld early in the season and/or during the rapid growth period of the crops. In many contexts of irrigation water management, water policy analysts will wish to consider the more realistic discrete-input simulation model for policy evaluation. Received: 1 November 1996     

Irrigation Policy Reforms for Rice Cultivation in Egypt

This paper reports a fieldresearch that evaluated irrigation waterdelivery options for promoting conservativewater use in rice cultivation. Ricecultivation in the Delta region of Egypthas grown dramatically, replacing cotton asthe major summer crop. The Ministry ofWater Resources and Irrigation is findingit difficult to limit the area planted torice since rice cultivation is profitableto farmers. A socially more feasibleoption is to encourage farmers to cultivateshort-season rice varieties. The Ministrycan then adopt the policy that will provideirrigation water to the farmers to supportcultivation of 120-day rice varietiesrather than 160-day traditional varieties. The field studies conducted for two yearsin the Nile Delta conclusively show thatthis is indeed feasible. Farmers in thedemonstration canal areas were able tosuccessfully finish 120-day ricecultivation, which allowed the Ministrystaff to end the rice water delivery about35 days early and realize substantial watersavings.     

‘More crop per drop’: how to make it acceptable for farmers?

In countries facing water scarcity, governmental water agencies try to transfer this constraint to farmers, e.g. by encouraging them to shift from traditional to localized irrigation methods to save water. However, water shortage is often much less a problem for farmers than soil limitations, their objective being mostly to maximize their income per cultivated area (US$ per hectare rather than per cubic meter of water). This discrepancy can only be solved if governments find ways to ‘transfer’ water scarcity, e.g. through economic incentives such as water pricing and/or subsidies. The aim of this study was to address the question of how to match the interest of both water managers and farmers. We aimed particularly at evaluating whether shifting to drip irrigation is a relevant way to save water and increase farmer's income.Our analysis was based on the interactive impacts among economic, environmental, technical and methodological parameters on the net productivity of two crops. We focused on the case study of Turkey considering two crops with contrasted gross productivity, tomato and cotton, characterized by partial vegetation cover during a large part of crop cycle. A 3D crop energy balance model was applied showing that crop transpiration is increased by up to 10% when shifting from furrow to drip irrigation. These results were used to correct the maximal evapotranspiration (ET_m), estimated with the simple “crop coefficient” (K_c) method, and then used to enhance net productivity estimation both for furrow and drip irrigation.The results suggest that water managers and farmers share a common interest in adopting drip irrigation of tomato. Inversely, interests divergence may increase with low/medium value crops as cotton; the combination between water pricing and subsidies could be a way of agreement, but it would require subsidies for irrigation equipment of at least 40%, for low water tariffs, to 60%, for high water tariffs, to make the transfer from furrow to drip irrigation acceptable. This approach appeared generic enough to be applied for other economic, technical or environmental conditions, to modernize irrigation by harmonizing constraints faced by water managers and farmers.     

Using satellite remote sensing to assess irrigation performance in Water User Associations in the Lower Gediz Basin, Turkey

The aim of this research was to assess the irrigation performance of the Salihli Right Bank, Salihli Left Bank, Ahmetli, Gokkaya, Turgutlu, Mesir, Sarikiz, Gediz, Menemen Right Bank and Menemen Left Bank Water User Associations (WUAs) in the Lower Gediz Basin in western Turkey, using remote sensing techniques. To reach this aim the performance of the irrigation system for the 2004 irrigation season was determined according to five indicators, namely overall consumed ratio (e_p), relative water supply (RWS), depleted fraction (DF), crop water deficit (CWD) and relative evapotranspiration (RET). Potential and actual evapotranspiration parameters used in determining these indicators were estimated according to the Surface Energy Balance Algorithm for Land (SEBAL) method using NOAA-16 satellite images.Seasonal averages of these indicators ranged from 0.59 to 2.26 for e_p, 0.47-1.66 for RWS, 0.43-1.31 for DF, 180.5-269.5 mm month⁻¹ for CWD, and 0.61-0.74 for RET. According to the seasonal average values of all the performance indicators, the irrigation performance of all WUAs was usually poor. The performance indicators showed that less irrigation water was supplied to WUAs than was needed. It was concluded that proximity to the source could be an advantage in obtaining water, and that when water was insufficient, groundwater in the crop root area could be used.     

Performance of Locally Managed Irrigation in Turkey: Gediz Case Study

Performance indicators for locally managedirrigation systems in the Gediz Basin,Turkey, show that during the first fouryears after management transfer there wasbeen a continued improvement in irrigationperformance. While the area cropped usingsurface water has only marginally improved,yields and water productivity have shownsignificant increases. These benefits canbe attributed in part to favorable marketconditions for cotton and grapes, but alsoto a management system that values level ofservice so that farmers are not constrainedby uncertainties in water deliveries. Individual systems are managed quitedifferently within the Gediz Basin showingthat there is scope for considerablediversity in Irrigation Associationspractices without affecting the resultingperformance of systems.     

A model for equitable distribution of canal water

The equitable distribution of canal water is imperative to ensure social justice as well as crop productivity. In north-west India and Pakistan, water from the tertiary canal (watercourse) is distributed to the farmers through a rotational system of irrigation. In this system the duration of supply to each farmer is in proportion to his holding in the outlet (watercourse) command, without considering the seepage loss. The rate of seepage loss increases with increase in length of watercourse from head to tail. Thus, the farmers in the lower reaches get much less water per unit area than the farmers in the upper reaches. The farmers must be compensated for the seepage loss. Therefore, a model was developed to ensure equitable distribution of water to the farmers located on a watercourse in proportion to their land holdings giving due compensation for the seepage loss. The model is based on the assumption that soil throughout the length of flow is homogeneous and loss through evaporation is negligible. The model developed ensures an equitable distribution of water to the farmers according to their land holdings. A comparison of existing and revised time allocation reveals that the farmers located in the upper reaches were getting more time (up to 12.2 min per unit area), while the farmers located in the lower reaches have been getting less time (up to 28.1 min per unit area). The existing allocation of time of 0.75 h per unit area to all the farmers according to the old rules was revised to 0.546–1.219 h per unit area from head to tail. The conclusions drawn suggest that the strategy developed here should be adopted elsewhere in the existing system of irrigation for equitable distribution of canal water. Received: 21 December 1999     

An economic evaluation of sugar cane production under different water supply systems in Thailand

In a vegetative crop like sugar cane, soil water stress will invariably result in reduced growth and yield. Under inadequate rainfall conditions such a crop needs supplemental irrigation to maximize the yield.The present article discusses the relationship between sugar cane yield and rainfall/irrigation requirements. Special attention is given to the potential sugar cane yields and benefit/cost ratios in the Malaiman area in Thailand, under four water conveyance systems (from low- to high-density irrigation and drainage network) and under optimized rainfed cultivation.A linear relationship between cane yield and water use is applied for the prediction of potential crop yields for the various water conveyance systems. These yields are compared with the actual cane production in pilot areas with different irrigation infrastructure, which has been monitored over a period of years. Actual yields fall short of predicted in all cases. This is mainly be attributed to the low cane prices, resulting in sub-optimal cultivation practices by the farmers.Prediction of potential sugar cane yields for local circumstances is quite possible. At present sugar cane price levels, development of a low-density irrigation infrastructure seems to be the most economical solution.     

Profitability analysis of a farming system in Africa

This analysis questions the assumptions that in a traditional farming system food production is primarily for home consumption and is not competitive with export crop (cocoa) production. Government planners and policy makers must look at the total operation of a farmer to understand the role of food crop production. In the case of Ghana in 1981 they needed to seek ways to make cocoa production relatively more profitable if the goal of increased cocoa production from small farms were to succeed.The analysis indicates why farmers were devoting scarce resources, particularly labor, to producing food crops in Ghana in 1981. Food crops were the most profitable both (1) in 1981 and (2) when the flow of income from the life of the trees was considered. Clearly, the farmers were demonstrating that they were rational economic men.In order to get an idea of what price cocoa must bring for it to be as profitable as the food crop systems, the price of cocoa was varied with all other prices held constant. The price of cocoa would have had to be approximately ¢400 per load of 30 kilograms in 1981. The government purchase price was ¢120 per load. Nor surprisingly, cocoa production in Ghana was declining steadily.     

Optimizing supplemental irrigation: Tradeoffs between profitability and sustainability

Water production functions are used to model yield response to various levels of supplemental irrigation (SI), to assess water productivity coefficients, and to identify optimum irrigation under various input-output price scenarios. The SI production function is taken as the difference between the total water production function (irrigation + rain) and that of rainwater. Theoretical analysis of the unconstrained objective function shows that the seasonal depth of SI to maximize profit occurs when the marginal product of water equals the ratio of unit water cost to unit product sale price. Applying this analysis to wheat in northern Syria, the production functions of SI under different rainfall conditions are developed. Coupled with current and projected water costs and wheat sale prices, the functions are used to develop an easy-to-use chart for determining seasonal irrigation rates to maximize profit under a range of seasonal rainfall amounts.Results show that, for a given seasonal rainfall, there is a critical value for the ratio of irrigation cost to production price beyond which SI becomes less profitable than rainfed production. Higher product prices and lower irrigation costs encourage the use of more water. Policies supporting high wheat prices and low irrigation costs encourage maximizing yields but with low water productivity. The resulting farmer practice threatens the sustainability of water resources. Balancing profitability versus sustainability is a challenge for policy makers. Our analysis can help national and local water authorities and policy makers determine appropriate policies for water valuation and allocation; and assist extension services and farmers in planning irrigation infrastructure and farm water management.     

Policies to support economic and environmental goals at farm and regional scales: Outcomes for rice farmers in Southern India depend on their resource endowment

Improving water use and nitrogen efficiencies is of overall importance to society at large - to conserve scarce water resources and prevent environmental pollution. Efficient cultivation practices for rice which had no yield penalty were not adopted by farmers because of the open access to water free of charge. Well-chosen combinations of policy measures are thus needed to stimulate adoption of new cultivation practices. We developed a multi-objective linear programming (MGLP) model to explore the impact of: (i) modified rice cultivation including water-saving irrigation on farm profit; (ii) water pricing and water quota government policies on adoption of modified rice cultivation by farmers; (iii) a combination of (i) and (ii) to achieve the objectives of both farmers and society at large, and (iv) to study the trade-offs between income, water and nitrogen use. The analysis was carried out on four rice-based farm types for the state of Tamil Nadu, South India. Model results showed that observed farm profit of all four farm types could be increased using current practices simply by optimizing land use for specific crops. Adoption of modified rice cultivation further increased farm profit. Water-saving practices were selected only when water pricing was introduced. Farm profits were reduced even at low water prices but were compensated by farmers through adoption of modified rice cultivation. The combination of policies that stimulate adoption of modified rice cultivation was effective in achieving both increased farm income and water savings. The required water prices differed across farm types and seasons and impacted poor resource-endowed farmers the most. Providing water quotas could protect the poor resource-endowed farmers. The model helped to identify the optimal water price and water quota for each farm type to achieve both the objectives of farmers and society at large. Opportunities for reducing water use and avoiding environmental pollution at acceptable profits are available for all farm types, but need to be tailored to the farmers’ resource endowments.     

大豆振兴背景下吉林省大豆供给反应研究——基于Nerlove模型的实证分析

大豆振兴背景下,大豆成为吉林省农业结构调整的关键作物。本文利用1985—2019年吉林省大豆相关数据,通过建立Nerlove模型对大豆供给反应进行分析,得出吉林省大豆短期供给价格弹性为0.23,而长期供给价格弹性为0.39,表明大豆供给对价格反应较为迟缓,缺乏弹性。测得预期价格调整系数为0.72,调整时滞为1.39,表明大豆种植户在调整种植面积行为上的滞后期约为1年。通过对吉林省大豆供给反应影响因素分析发现滞后一期的大豆播种面积、大豆市场价格、大豆与玉米单位面积收益比和大豆相关政策都对当期大豆播种面积有显著影响。基于此本文剖析了各影响因素的作用机理,提出深化农业供给侧结构性改革、完善米豆轮作制度和大豆生产者补贴政策,稳定价格、改善大豆与玉米的比价关系,提高大豆种植收益等建议,以鼓励吉林省农户大豆种植积极性,保障大豆良性供给。     

Determining the disaggregated economic value of irrigation water in the Musi sub-basin in India

In this paper the residual method is used to determine the disaggregated economic value of irrigation water used in agriculture across crops, zones and seasons. This method relies on the belief that the value of a good (its price by its quantity) is equal to the summation of the quantity of each input multiplied by its average value. By applying this method to the Musi sub-basin; a subdivision of the Krishna basin in India, it was found that the value of irrigation water use is not equated across the crops, zones and seasons. The reasons why there is no sinlge value of irrigation water use are suggested. As farmers do not have perfect knowledge, do not all possess the same resource base, plant different crops for a variety of reasons (some for a financial return on land instead of water and others for sustenance), possess different crop rotation practices and are possibly riks adverse, they all value water differently. However, the results need to be interpreted with care as the crop with the lowest return to water is probably not the one to be sacrificed if water is restricted, since farmers plant crops for a variety of reasons (and sometimes not for the highest return to water that they can achieve).     

Study of feasibility of night-closure of irrigation canals for water saving

The feasibility of closing distributary canals at night was investigated in a recently modernized surface irrigation system in Pakistan, the Upper Swat-Pehur High Level Canal system. Increased water supply, greater delivery capacity and the introduction of downstream control potentially allow more flexible service. In the command area of Maira branch of this system, farmers are anyway abandoning night-time irrigation, as they can meet their needs from improved supply during the day. They practice night irrigation only during the times of peak crop water demand. The rotational delivery system, known as warabandi in the sub-continent and Dauran in Arabian countries, has even broken down in the day in some parts of the command area. This is believed to be typical of systems with more than adequate water supply.A simulation study was undertaken using the CanalMan software developed by Biological & Irrigation Department, Utah State University, Utah Logan, USA. Primary data collected in one distributary canal and the two minors connected to it was utilized for simulations. The feasibility of night-time closure depends on the speed of filling and emptying the canal each day, and the time required to meet full irrigation demand during the day. The results show that where canal lengths are less than 5 km, in this system, there is good potential to make savings, which can be realized at system level through reduced demand on supplemental supplies from Tarbela Dam.     

KDF-1．1型地膜覆盖机的使用及故障排除

地膜覆盖技术能提高地温，保墒保肥，改善水、肥、温度、光照等作物生长条件，早播早收，促进作物增产，增加农民收入。同时能减轻劳动强度，质量好，省时省工效率高，深受广大农民欢迎，在日益广泛的使用中用户应该了解使用注意事项和故障排除等知识。     

模糊数学在农业水价中的应用

基于模糊数学理论,综合考虑影响农业水价的环境、经济和社会3方面因素,选取水质、水资源量、人均可支配收入、技术成本投资和农民满意程度5项影响因素,建立了农业水价模糊数学综合评价模型,并应用于实际工程。以云南某大型灌区为例,测算的农业水价为0.99元/m3,与现行水价0.08元/m3差距较大,故应在农民可接受的范围内提高农业水价。合理的农业水价,可减少农业水资源浪费,提高水资源利用率,对实现农业节水具有重要意义。      

Conjunctive use of canal and groundwater in Punjab,Pakistan: management and policy options

Data from 41 watercourses commands in Pakistan show that, as expected, farmers in head end reaches of canals receive more canal water than those in tail end reaches. Contrary to conventional wisdom, however, these head end farmers also use more groundwater than those at the tail end. Overall, groundwater plays a more important role in irrigation than surface water, ranging from 65% dependence on pumped water in head end areas to over 90% in tail end areas. This means that groundwater is no longer supplemental to canal water, but is an integral part of the irrigated agricultural environment. However, the cropping choices of farmers appear to reflect the amount of good quality canal water they receive: head end farmers are able to grow more high value basmati rice in the summer and more vegetables in the winter, leaving tail enders to rely on less valuable crops such as fodder and wheat.Tail end areas are not only deprived of their fair share of surface water: they have to pump proportionately more groundwater which shows decreasing quality towards the tail. Typically, head end areas have groundwater with EC values of less than 1.0 dS/m, rising to over 2.0 dS/m in tail end areas. When the quality of both surface and groundwater used by farmers is examined, only the top 40% of the distributary gets water of adequate quality, the next 40% get below average quality, while the tail 20% of farmers irrigate with water that is classified as saline.Because of higher dependence on more expensive groundwater tail enders use less water per unit area, thereby reducing the leaching requirement. The result is a clear increase in soil salinity from head to tail along distributary canals, and there is some evidence of land abandonment in tail end watercourses due to excess salinity.The implications of these results are far reaching. Government policy includes plans to divert significant quantities of fresh canal water to areas underlain by saline groundwater on the basis that farmers already have adapted to pumping fresh groundwater. The results reported suggest that if this policy were implemented, there is a risk that over-dependence on fresh groundwater could lead to an intensification of the rate of soil salinization and deterioration of quality in areas currently classified as fresh groundwater zones.At present, the location and utilization of privately owned shallow tubewells is not monitored, and thus it is not possible for government agencies to determine just how much water of different qualities is being used. Further, canal water deliveries, public deep well monitoring, watercourse monitoring programs, soil salinity measurements, and agricultural performance monitoring are all scattered among different agencies and organizations, making the task of effective conjunctive management of surface and groundwater even more difficult.Conventional wisdom: Groundwater in Pakistan ... where it exists within the canal system ... is used to supplement surface water supplies to meet peaks in demand. (WAPDA, 1990)     

Productivity of Rice—Wheat Cropping System in a Part of Indo-Gengetic Plain: A Spatial Analysis

Investigations were made to study the effect of unequal distribution of canal water in land and water productivity of the rice—wheat cropping system in terms of head—tail relationship in Bhakra Canal command, Haryana. Information on water supply, agronomic practices, crop yield, etc.,were collected from 216 farmers comprising 36 farmers each from the head, middle, and tail watercourses of two minors during year 2000–01. The unequal supply of canal water and presence of marginal quality groundwater creates large variations in the cropping pattern, irrigation application, and land and water productivity of the irrigation system. The groundwater of tail reaches, being saline in nature, was about 25% less productive as compared to head reaches. The unavailability of canal water in the tail reaches creates more dependency on groundwater. Due to its poor quality the crop production in the tail reaches was less by 10 to 20% in case of wheat, and 20 to 40% in case of rice, as compared to head reaches. Groundwater transfer from head to tail reaches and cultivation of low water requiring salt tolerant crops/varieties would be helpful in reducing the productivity gap and increasing the profitability of the farms in the region.     

Comparing water management in rice-wheat production systems in Haryana, India and Punjab, Pakistan

The intensive irrigated rice-wheat systems in the northwest Indo-Gangetic Plains of South Asia are built on a long tradition of canal irrigation and the more recent advent of tubewells. Findings from farm surveys are used to examine water management and water productivity in the rice-wheat belt of India's Haryana State and Pakistan's Punjab province. Attributes of the irrigation sources help explain the widespread interest in groundwater use and the relative demise of canal water use. In each area groundwater now is the main irrigation source, used either solely or in conjunction with surface water. The ownership of tubewells is near universal among the surveyed farms, whereas conjunctive water use is more widespread during the monsoon season, among better endowed farmers and in the Pakistan Punjab. In Pakistan Punjab farmers primarily rely on diesel powered tubewells whereas Haryana farmers mainly use relatively cheaper electric power. Water productivity indicators for rice are markedly lower than those for wheat—largely reflecting significantly higher water inputs in paddy cultivation—but also vary between the study areas and by the prevailing water use, reflecting the limited incentives for farmers to use water wisely. A combination of technological, land use and market based approaches is likely to be most effective in achieving sustainable water management in these intensive cereal systems.