MIRRIG: A decision support system for design and evaluation of microirrigation systems

The decision support system (DSS) MIRRIG has been developed to support the design of microirrigation systems and to advise farmers as a result of field evaluations. It is written in Visual Basic 6.0, runs in a Windows environment, and uses a database with information on emitters and pipes available in the market, as well as on crops, soils and the systems under design. MIRRIG is composed by design and simulation models and a multicriteria analysis model that ranks alternative design solutions based upon an integration of technical, economic and environmental criteria. User friendly windows are adopted for handling the databases and to manage the sub-models. The model allows creating and comparing a set of design alternatives relative to the pipe system and the emitters, either drip or microsprinkling emitters. For each alternative, the pipe system is sized and the irrigation system is simulated to produce performance, environmental and economic indicators. These include uniformity of water application, potential for contamination with agrochemicals due to water percolation, and installation and operation costs. Those indicators are used as attributes of the selected criteria. All alternatives are then compared and ranked through multicriteria analysis where the weights giving the relative importance of the adopted criteria are defined by the user. These procedures allow selecting the best design alternative and solving the complexities involved in the design of microirrigation systems. The model is available from the website www://ceer.isa.utl.pt/cms or by contacting cpedras@ualg.pt.     

An approach to multi-criterion evaluation of irrigation system performance

Irrigation systems aim to meet multiple objectives and performance must therefore be assessed using quantifiable measures for each. It therefore becomes an extremely difficult task to capture the valuation of all of them simultaneously and to mentally process the trade-offs between them in order to arrive at an overall impression of system performance. There is a need for a methodology which provides a systematic approach to comparing and combining the components of overall performance.Multi-Attribute Utility Theory offers an attractive approach to assessing performance of irrigation systems in the form of a utility function which reflects the strength of preferences and trade-offs between individual performance criteria. The method is described and demonstrated on the basis of a case study of irrigation in Sudan.     

Prototype decision support system based on the VegSyst simulation model to calculate crop N and water requirements for tomato under plastic cover

The simulation model VegSyst was calibrated and validated for tomato grown under plastic cover. Calibration was conducted with an autumn–winter soil-grown crop, and validation with five crops with differences in season, cropping media, and site. VegSyst accurately simulated daily dry matter production (DMP), N uptake, and ET_c. Comparing simulated and measured values by linear regression, slope and intercept values were not statistically significantly different (P < 0.05) from 1 and 0, respectively. Slopes between simulated and measured values indicated average differences of 4, 2, and ?1 % for DMP, N uptake, and ET_c, respectively. Model performance was good with autumn–winter and spring cropping cycles, and in soil and substrate. A prototype decision support system (VegSyst-DSS) based on VegSyst was developed to calculate daily irrigation and N fertilizer requirements and nutrient solution [N] for fertigated tomato. N fertilizer requirements are based on crop N uptake and consider soil mineral N, and N mineralized from manure and soil OM and the N efficiency of each N source. Irrigation requirements are based on ET_c and consider application efficiency and salinity. VegSyst-DSS requires very few inputs which are all readily available to farmers and advisors. Scenario analysis compared a scenario representative of local farming practice, where N supplied from soil is not considered, with scenarios with different amounts of N supplied from soil mineral N at planting and mineralization of soil OM and of manure. Relative to the scenario representative of farmer practice, VegSyst recommendations resulted in reductions of 34–65 % in fertilizer N.     

Introducing monitoring and evaluation into main system management — a low investment approach

The need to develop a framework for performance assessment of irrigation schemes is increasingly dominating discussions in the field of water management. This paper supports the view that the introduction of monitoring and evaluation of water distribution systems as a part of the day to day management activity is a desirable step in the improvement process and can be introduced at little cost.Data already being routinely collected in many schemes provide a valuable insight into scheme operation and can be used to improve planning of operating strategies. One aim of the study being carried out by Hydraulics Research and the Irrigation Department at Hakwatuna Oya in Sri Lanka is to improve the standards of main system management within the constraints of the existing physical infrastructure through the provision of timely performance data. A microcomputer has been installed at the project office to store and analyse rainfall, flow and field wetness data, and to provide performance reports on a regular basis. Early results suggest that the timely processing of an increased level of data collection is effective for both the identification of problems and the quantification of potential for improvement. Particular emphasis is given to providing the necessary software tools and training such that routine monitoring and evaluation becomes an accepted and sustainable proposition.     

VegSyst, a simulation model of daily crop growth, nitrogen uptake and evapotranspiration for pepper crops for use in an on-farm decision support system

The VegSyst simulation model was developed to assist with N and irrigation management of sweet pepper grown in plastic greenhouses in the Mediterranean Basin. The model was developed for use in an on-farm decision support system with the requirement for readily available input data. Dry matter production (DMP), crop N uptake and crop evapotranspiration (ET_c) are simulated on a daily basis. DMP is calculated from daily fraction of intercepted photosynthetically active radiation (PAR), PAR radiation, and radiation-use efficiency. Fraction of intercepted PAR is calculated from relative thermal time. Crop N uptake is calculated as the product of DMP and N content which is described by a power function of DMP. ET_c is the product of daily reference evapotranspiration (ET_o) using an adapted Penman–Monteith equation, and a daily simulated crop coefficient value. The VegSyst model for soil-grown, greenhouse pepper was calibrated in one crop and validated in three different crops. In the validation, the model accurately simulated crop growth, N uptake and ET_c. Relative to measured values, simulated DMP at final harvest was 0.89–1.06, and crop N uptake was 0.97–1.13. Simulated cumulative ET_c for complete crops was 0.95–1.05 of measured values.     

农情监测多旋翼无人机系统开发及性能评估

现代农业要求农业生产者实时、准确、全面地了解农作物的生长环境和生长状态。与传统的人工田间调查方式相比,无人机是一种高效的农田信息获取平台。本研究将自主研发的八旋翼无人机与农田信息采集设备进行整合,形成了一套用于农情监测的无人机系统,实现了无人机按照预设航线自动巡航并采集农田遥感图像、地理位置信息以及环境照度信息。经测试,在飞行中,图像采集设备能够稳定维持垂直对地的姿态并进行拍摄,采集的数据能够拼接成完整的农田正射影遥感图像。测试结果表明研发的无人机系统能够满足低空农情监测作业要求。与商业化产品相比,该系统避免了因任务设备与飞机独立工作而导致重拍、漏拍的情况,实现了无人机与任务设备高效协同作业。     

Changing systems for supporting farmers' decisions: problems,paradigms, and prospects

All correct reasoning is a grand system of tautologies, but only God can make direct use of that fact. The rest of us must painstakingly and fallibly tease out the consequences of our assumptions. (Herbert Simon in ‘The Sciences of the Artificial’, p.15)

Decision support systems (DSS), like other information systems (IS) before them, were designed to serve functions deemed by ‘management scientists’ to be potentially useful to managers. But the unwelcome fact is that the use of agricultural DSSs by managers of farms has been low. This paper probes possible reasons for this through interpretation of agricultural DSS case histories and several strands of relevant social theory. From nine cases of DSS development effort and 14 products interpreted comparatively, a number of generalisations are made that serve as reference points in the following search for explanation in theory.First, the nature of management practice of family farms is explored and differences between the internal structure governing personal action and the scientific approach to practice are contrasted. Next, the interaction between the nature of the particular action/practice and the nature of the DSS is explored. A DSS designed to provide integrated, optimal recommendations for management typifies the DSS as a proxy for a manager's decision process. Examples of elaborate expert systems that simply were not used dramatically illustrate the resistance of family farmers to have their decision processes by-passed. On the other hand, the DSS designed to serve as a tool in a modified decision process is shown to have experienced higher use, by deriving and exploiting ‘deep,’ abstract information about the system, by introducing a powerful ‘logic,’ or a combination of both.A number of the referenced case stories demonstrate the resurgence of the decision support mode whereby the simulator is in the hands of an expert intermediary as an alternative to easy-to-use software in the hands of a farmer. This is the mode of operational research/management science, which preceded the DSS.In comparison with hierarchical organizations, available options for overcoming the persistent ‘problem of implementation’ of the DSS in family farms are inherently weak. This focuses attention on the importance of the relationship between the DSS developer and the potential user. Drawing on a classic typology of possible configurations of ‘understanding’ between the scientist and the manager, four approaches to intervention are discussed. Three entail a degree of engagement that qualifies them as ‘participative.’ But one of these constitutes a departure from the DSS and broader IS traditions that places it in another paradigm. In this ‘mutual understanding’ relationship, intervention intent shifts from educating and persuading to recognition of and respect for other ways of viewing the world. This opens up the opportunities for co-creating information systems that utilise the comparative advantages of both practical and scientific knowledge. Intervention emphasis shifts from prescribing action to facilitating learning in actions.Although the DSS has fallen far short of expectations in its influence on farm management, the experience has been instructive in multiple ways to both farmers and professionals in agriculture. In many cases, farmers learned from the DSS and could then jettison it without loss. From disappointments scientists have sometimes learned what was needed to achieve a better outcome. From collated DSS experiences, important lessons for the future can be drawn.The paper concludes by conjecturing that the future of the DSS and related ISs, while more limited than once imagined, holds promise in four directions: a ‘small’ tool for aiding farmers' tactical decisions; a versatile simulator as a consultant's tool; a versatile simulator as the core of a facilitated ‘learning laboratory,’ and a formal framework that supports regulatory objectives in constraining and documenting farming practice.     

Sustainable land use and food security in developing countries: DLV's approach to policy support

During the past decades, major changes have taken place with regard to the available policy instruments for food security and rural development. These changes are reviewed against the background of the structural adjustment programmes carried out in the agricultural sector. The linkages between agricultural policy and farmers' supply response are discussed, emphasizing the influence of macro-policy for decision-making at the micro-level of a farm household. An integrated bio-economic modelling framework is presented that allows a better understanding of the effects of macro and sectoral policy interventions for food security and sustainable land use at the farm and (sub)regional level. Critical areas where the understanding of macro–micro linkages is still weak are identified. Major conclusions regarding a suitable analytical framework for policy analysis and support are presented.     

I. A decision support system to improve planning and management in large irrigation schemes

This paper describes a decision support system (DSS) that was developed to improve planning and management for the large irrigation schemes in the Alentejo region of Portugal. The system was designed to help in the analysis and evaluation of the crops and crop systems that can potentially be cultivated, together with identification of limitations affecting crop selection and crop yields. It integrates socio-economic and biophysical data at the field level to analyse the performance of an irrigation scheme in terms of the adoption of irrigation by farmers and farmers’ incomes. The final output is given in the form of specific actions and policies for the irrigated areas. The DSS was designed initially to be used in the Alqueva project, a large irrigation scheme that is under construction in Alentejo. Nevertheless, the final framework is generic in nature, being suitable for planning and policy evaluation in other large irrigation schemes.     

Analysing agricultural users’ patterns of behaviour: The case of OPTIRas™, a decision support system for starch crop selection

Redesigning IT systems for specific user groups encompasses a lot of effort with respect to analysing and understanding user behaviour. The goal of this paper is to provide insights into patterns of behaviour of agricultural users, during the usage of a decision support system called OPTIRas™. This system aids agricultural users in their cultivar selection activities. We analyse logs resulting from OPTIRas™, and we get insights into user’s navigational patterns. We claim that the results of our analysis can be used to support the redesign of decision support systems in order to address specific agricultural users’ characteristics.     

我国出口退税政策的实施绩效评价与创新研究

出口退税政策是税收政策的重要组成部分,在许多方面都具有非常重要的作用.目前我国出口退税政策存在的问题表现为出口退税办法不统一、退税手续繁杂、退税效率低下、出口退税管理体系不完善、出口骗税现象严重等,因此要构建稳定的出口退税机制、建立出口退税的监督制约机制.     

Use of simulation models to evaluate irrigation performance including water productivity, risk and system analyses

 Worsening water scarcity will increase pressure to use water more productively. In the classical view of irrigation research, some important aspects are often ignored: the total water balance approach, productivity of water, food security, and irrigation-system level analyses. These four approaches were evaluated using a detailed agro-hydrological model applied to an irrigation system in western Turkey. Emphasis was placed on the two dominant crops in the area: cotton and grapes. According to the classical point of view, the only result would be to irrigate the cotton with 1000 mm and the grapes with 800 mm. From the water productivity point of view, however, the water productivity of grapes appeared to be maximal without any irrigation; while for the cotton, irrigation at 600 mm maximizes water productivity. To minimize risks and increase yield stability, grapes perform better than cotton. Finally, from the irrigation system point of view, decisions can be made about the desirable cropping pattern and the distribution of water between crops. With limited amounts of water available for irrigation, a cropping pattern consisting mainly of grapes is desired; while with higher water availability, a mixture of cotton and grapes is preferable. The methods presented provide a clear methodology with which to achieve the most productive use of water. Received: 3 June 1999     

拖拉机提升器的基本参数和性能评价

分析了关于提升器基本参数和性能评价方面目前存在的问题,阐述了提升器的主要性能和提升特性,并提出了关于提升器基本参数和性能评价的若干意见。     

Development and evaluation of a pastoral simulation model that predicts dairy cattle performance based on animal genotype and environmental sensitivity information

A dairy cattle simulation model for pastoral systems that considers how dairy cow genotypes respond to different environments is described. The dairy cow is represented by five modules for maintenance, pregnancy, growth, body energy reserves and lactation with the influence of environmental factors on processes included within each module. Feed intake is predicted based on the requirements for maintenance, growth and pregnancy, and the dairy cow’s potential for yields of milk, fat and protein and body fat change in a given environment. The effects of various temporary environmental factors such as cow body condition score, climate, feed quality and the stage of pregnancy are all considered when predicting yields of milk, fat and protein, energy and dry matter intake. The model was evaluated using information from a prior experimental study with 1990s Holstein-Friesian dairy cattle of North American/European or New Zealand origin managed in a pasture-based system in early to peak lactation. The model was able to predict, to a high degree of accuracy, mean values for yields of milk, fat and protein, and concentrations of fat and protein. However for individual cows, feed intake and live weight change were less reliably predicted. The major source of error was a lack of simulated variation, rather than any systematic bias. The major advance of the model is its ability to predict performance from genetic and environmental sensitivity information for particular breeds, and its ability to predict feed intake and yields of milk, fat and protein concurrently.     

LUSE,a decision support system for exploration of rural land use allocation: Application to the Terra Chá district of Galicia (N.W. Spain)

This article describes LUSE, a system for exploration of rural land use allocations (total area devoted to each kind of use) by multiobjective linear programming methods. The objectives pursued are maximization of gross margin, employment in agriculture, land use naturalness and traditional rural landscape, and minimization of production costs and use of agrochemicals. The constraints on the areas devoted to the land uses considered in addition to those imposed by their joint and individual availabilities, are that they must reach levels considered to satisfy existing demand for those uses or their products, and that the areas devoted to maize and fodder must be sufficient for maintenance of dairy farm production. The program generates comprehensive samples of the Pareto-optimal set, and also allows interactive convergence on a solution that is satisfactory to the decision-maker or interactive exploration of the Pareto-optimal set. The system is currently parameterized for use in an area of Galicia (N.W. Spain), but is easily adaptable to other geographic locations.     

Computer simulation of monitoring herd productivity under extensive conditions: Sampling error of herd size and offtake rate

Monitoring extensive pastorialist herds was simulated using a personal computer program designed to yield balance sheets for numbers and annual rates of births, mortalities, cullings and herd growth, as well as for herd structure in successive periods of weeks or months. Instead of calving rate, the program used frequency distributions of first parturition age and parturition interval, together with sterility rates, to generate individual reproduction. It took 15 years for herd size to become free from carry-over effects due to inherent herd history. Offtake rate seemed to be a convenient statistic for measuring productivity under the conditions of stable environment and herd policy. It was not auto-correlated and its sampling error followed binomial expectation. The standard error of annual offtake rate was large and, even with monitoring periods of as much as two years, some herds were three or four times as productive as others. A menu-driven program that can handle different animal species and various herd development policies without prior modification can be useful for testing hypotheses which would otherwise be difficult to treat mathematically. Practical monitoring schemes should maintain corresponding packages for routine purposes.     

Energy analysis of irrigation delivery systems: monitoring and evaluation of proposed measures for improving energy efficiency

In Spain, the Ministry of Industry is implementing actions for analyzing the energy efficiency of Water User Associations (WUAs) by using energy indicators and proposing measures to improve the use of energy. The main objective of this work was to develop tools to improve energy efficiency in WUAs. These tools were validated by utilizing them in the energy analysis of 15 WUAs located in Castilla-La Mancha Region (Spain) during the 2007 irrigation season. These tools were also utilized for the proposal of measures to improve the use of energy. The proposed measures were monitored and evaluated in 7 of the 15 WUAs during the 2008 irrigation season. The developed tools were integrated into a Decision Support System for performing energy analysis and for proposing measures of energy efficiency improvement. In most of the study cases, an improvement of the energy efficiency after the implementation of the proposed measures was detected, with an average energy saving of the 10.2%.