An international collaborative network for agricultural systems applications (ICASA)

In the 1970s and 1980s much progress has been made in studying agricultural production systems by using simulation modelling of agronomic processes. The International Benchwork Sites Network for Agrotechnology Transfer (IBSNAT) group in the USA and the group around Professor Kees De Wit in Wageningen were active in this new area of research which created an important ‘niche’ within the agricultural sciences because of its integrative, interdisciplinary character and its focus on quantitative, process-based approaches. A first joint scientific meeting of the two groups was held in Bangkok in 1991 (SAAD1 conference: Systems Analysis for Agricultural Development). At the SAAD2 conference at IRRI in 1995, in which also other groups took part, notably the Agricultural Production Systems Research Unit (APSRU) group from Australia, the International Consortium for Agricultural Systems Applications (ICASA) was established as a forum for researchers engaged in the study of agricultural systems at different spatial scales ranging from fields, farms to regions and beyond. The ICASA is an informal network with a focus on three major activities: (1) sharing experiences and joint development of compatible software allowing more widespread use of models having been developed by various member groups; (2) organization of joint courses on different aspects of dynamic modelling of agricultural production systems. There is an increasing interest in such courses, also in developing countries, and local researchers increasingly take an active part in them; and (3) joint research on projects dealing with dynamic characterization of agronomic production systems at different spatial scales. ICASA researchers take part in eco-regional methodology development, through projects that are funded by the Dutch and Swiss governments, with ISNAR acting as the administrative agency. ICASA intends to be an effective platform on which researchers, stakeholders and policy makers can interact.     

Approaches to modular model development

One of the main goals of the International Consortium for Agricultural Systems Applications (ICASA) is to advance the development and application of compatible and complementary models, data and other systems analysis tools. To help reach that goal, it will adopt and recommend modular approaches that facilitate more systematic model development, documentation, maintenance, and sharing. In this paper, we present criteria and guidelines for modules that will enable them to be plugged into existing models to replace an existing component or to add a new one with minimal changes. This will make it possible to accept contributions from a wide group of modellers with specialities in different disciplines. Two approaches to modular model development have emerged from different research groups in ICASA. One approach was developed by extending the programming methods used in the Fortran Simulation Environment developed in The Netherlands. This method is being used in revisions of some of the Decision Support Systems for Agrotechnology Transfer crop models. A simple example of this approach is given in which a plant growth module is linked with a soil water balance module to create a crop model that simulates growth and yield for a uniform area. The second approach has been evolving within the Agricultural Production Systems Research Unit group in Australia. This approach, implemented in software called Agricultural Production Systems Simulator, consists of plug-in/pull-out modules and an infrastructure for inter-module communication. The two approaches have important similarities, but also differ in implementation details. In both cases, avoiding reliance on any particular programming language has been an important design criterion. By comparing features of both approaches, we have started to develop a set of recommendations for module design that will lead to a ‘toolkit’ of modules that can be shared throughout the ICASA network.     

Software for missing data error analysis of Penman-Monteith reference evapotranspiration

The most common approach for the estimation of crop water requirements is to pair a crop factor with the evaporation from a reference surface. In this study, a user-friendly computer tool was developed to facilitate the calculation of daily FAO (Food and Agricultural Organization of the United Nations, Rome, Italy) Penman-Monteith reference crop evaporation (ET₀), and to estimate errors that can arise if solar radiation, wind and vapour pressure data are not available. The ET₀ calculator imports comma, tab or space-delimited daily weather data files in any user-specified format. It displays graphically and processes statistically, ET₀ values calculated from full and incomplete weather data sets. The program is written in Delphi with a Paradox database and includes a comprehensive, context-sensitive help file. Sensitivity analyses were carried out for three locations as examples. The error in predicting ET₀ using estimated weather parameters was reduced by using 5-day averages of ET₀ rather than daily values. Although some error is incurred by estimating weather parameters, this is somewhat compensated for by the absence of any error that may have been associated with the measurements.     

IMPACT: Generic household-level databases and diagnostics tools for integrated crop-livestock systems analysis

We outline the need for generic crop-livestock systems databases and data standards for comprehensive systems analysis in developing countries. We also indicate the type of data that such databases should contain and review how they can be collected. We describe IMPACT, a database and analysis tool that we have developed that goes some way to meeting the demands that may be made of such systems data. Analysis tools, links to models and uses of such databases are briefly described and illustrated with case studies from Kenya, Ghana and Sri Lanka. The paper concludes with a discussion of the needs for a more coherent integration of global data collection and improved sharing of data for better articulation of research and development outcomes in developing countries.     

茎变差监测数据标准化处理与转换系统的设计与开发

茎变差监测数据标准化处理与转换系统,是中国农业科学院农田灌溉研究所研制的作物茎直径生长测量仪的配套软件,能将茎变差系统监测到的电信号根据一定的规则和方法,转换为指导作物实时灌溉的指标.开发该系统的目的是指导仪器使用者对监测到的茎变差数据进行标准化处理和转换,以便科学合理地进行灌溉决策.该系统采用B/S开发模式,运用C#...     

Tactical management of pasture fallows in Western Australian cropping systems

Agricultural systems in the Western Australian wheatbelt are increasingly moving towards specialist crop production due to elevated cereal prices, depressed markets for livestock products, and ongoing labour scarcity. However, the profitability of crop-only farms is threatened by increasing levels of herbicide resistance and declining soil fertility. This study determines the value of ungrazed pasture fallows grown tactically between crop phases to address these agronomic constraints. A novel metaheuristic optimisation technique, compressed annealing, is used to determine profitable flexible land-use sequences in a complex simulation model. Tactical use of single-year, ungrazed pasture phases is found to be more valuable than the use of break crops in crop-only systems. In contrast to previous analysis, it is identified that rotation of short periods of crop and pasture is more profitable than extended phases of both. Effective weed control without dependence on selective herbicides is the key agronomic characteristic determining the value of intermittent pasture phases. Accordingly, the number of single-year pasture phases employed in a sequence should increase with the severity of herbicide resistance. Compressed annealing is shown to be a practical method of identifying profitable land-use sequences that respond to information that unfolds dynamically.     

A GIS-based model to estimate the regionally distributed drought water demand

A GIS-based Water Resources and Agricultural Permitting and Planning System (GWRAPPS) was developed by integrating the Agricultural Field Scale Irrigation Requirements Simulation (AFSIRS) crop water model, a geographic information system (GIS) and a database management system within an ArcGIS framework. GWRAPPS facilitates the quantification of irrigation water for regional planning and farm scale permitting purposes under statistically average to drought conditions using spatially distributed soils, land-use, and long-term daily climate data. In addition, the system provides regional estimates of daily water withdrawals that are necessary for input into conjunctive surface/groundwater models. This paper presents two Florida case studies that demonstrate GWRAPPS’ ability to characterize irrigation needs based on spatially heterogeneous soil and climate data in contrast to a spatially lumped model. The results show that while inclusion of soil heterogeneity is important to capture water requirements at individual farms, regional water demands are adequately captured using each farm’s predominant soil.     

国内外暗管排水研究知识图谱可视化分析

【目的】探明国内外暗管排水研究领域的研究内容、发展动态。【方法】基于CNKI与WOS数据库,采用科技文本挖掘可视化软件VOSviwer对国内外暗管排水研究的文献引文数据进行了科学叠加可视化分析,国外机构耦合分析,国内外引文关键词共现分析,国内外研究人员合作网络分析。【结果】通过科学叠加图谱,从学科的宏观角度分析了暗管排水研究学科发展方向;通过国家合作网络分析,得出了该领域的研究强国;USA、Canada、Germany、China、Netherlands、France、Sweden、England、Denmark、Switzerland;通过机构耦合分析,确定了暗管排水研究高影响力研究机构;USDA ARS、Iowa State University、University of Illinois、University of Minnesota、Purdue University、Agriculturea nd Agri-Food Canada、U.S.Geological Survey、Swedish University of Agricultural Sciences、Ohio State University;通过国内外关键词共现网络图比较,揭示了国内外暗管排水研究的主要内容上的差异;通过国内外合作网络图分析,得出了国内外暗管排水核心研究学者之间的合作关系及他们为推动暗管排水研究所做的贡献。【结论】我国的暗管排水研究领域正处于引进吸收与发展的状态,在流域尺度暗管排水的研究、田间尺度农药与磷淋失机制、排水水质净化等方面研究薄弱。未来的新兴趋势是从暗管排水释放源头到排水的末端建立系统的研究体系,考虑多元化因素的排水管理,工程技术上在田间排水源头采用建立反硝化除氮生物反应池改善排水水质,农艺措施上非耕作期进行覆盖作物种植研究,气候变化与暗管排水研究耦合也将成为研究热点。     

作物长势信息空间分析系统设计

为了满足作物长势动态测量的要求,设计了作物长势信息空间分析系统,针对作物冠层信息获取手段及其数据特点设计相应的功能模块。系统主要由光谱文件管理、定点作物光谱分析、动态采集监测、空间数据分析等功能模块组成。系统能够兼容多种光谱文件格式,具有两种空间数据分析方法,配有专家数据库接口,具有较强的二次开发潜力。该系统配合车载作物长势检测平台,对玉米的长势空间分析进行了应用效果验证,结果证明：该系统能够实时读取和分析车载式作物长势检测平台的动态数据,通过不同的空间插值方法能够掌握冠层生物信息空间分布状况。该系统为车载动态测量提供了良好的技术支持,可为制定相应的精准管理决策提供理论依据。     

农艺与物联网下的智慧农业

农业物联网在大棚控制系统中的运用实现了农作物增产、改善品质、调节生长周期和提高经济效益的目的。从物联网出发,结合农艺技术和物联网技术,提出了智慧农业系统结构总体框架,为用户实时监控农田并进行信息决策提供了技术支持,真正实现了农业管理的智能化,符合现代农业的发展。      

Simulation of the soil-water dynamics and corn yields under deficit irrigation

Summary A simulation model capable of predicting the yield response of corn to a limited water supply was developed by combining two existing mathematical models. The resulting computer model was evaluated using experimental data taken under a wide range of soil moisture conditions. The soil profile water balances was simulated using SWATRE and SUCROS was used to model the crop growth in response to environmental conditions. In addition to the integration of the two existing models, some minor changes were made to each in an effort to improve the accuracy of the combined models. The model input parameters were derived entirely from published literature. The experimental data necessary for model validation were available from irrigation studies at the Sandhills Agricultural Laboratory of the University of Nebraska. These experiments not only provided the required input soil and climatic data, but also the observed irrigation levels, soil moisture distributions and crop yield required for model validation. Initial evaluation of the computer model indicates that the combined model adequately describes crop evapotranspiration, soil moisture extraction and crop yield under a fairly wide range of soil moisture stress. Additional modifications for the prediction of leaf area expansion and senescence, especially under moisture stress, are needed to improve the accuracy of the model.     

Stability of crop coefficients under different climate and irrigation management practices

Summary The effects to climate and management practices on crop water requirement coefficients were studied for a soybean crop growing on a sandy soil using a mechanistic model that computes evaporation and transpiration in response to soil, crop, and climatic factors. It was found that seasonal errors could the as high as 190 mm when crop coefficients developed under one set of conditions were used under different climate and management conditions. The largest error in ET occurred when vapor pressure was reduced from 26 mb to 14 mb; next in importance were site differences in wind speed, radiation, irrigation interval, temperature and planting date. Correction factors needed to adjust crop coefficients to those site specific conditions ranged from 0.73 to 1.30 depending on the time of season and climate or management variable that was changed. When the overall crop coefficient was divided into a plant specific and a soil specific coefficients, the plant coefficient was relatively stable compared to soil coefficients. The results of this study can help establish a practical range of conditions over which crop coefficients developed at one site can be used to compute the appropriate values for sites where measurements have not been made.Approved for publication as Florida Agricultural Experiment Station Journal Series No. 9514. This research was partially supported by the US AID project, International Benchmark Sites Network for Agrotechnology Transfer, No. DAN-4054-c-00-2071-00     

基于数据库的温室作物生长管理智能决策支持系统的研制

以Delphi7．0为软件开发环境，构建了温室作物生长管理智能决策支持系统。提出了温室作物生长管理智能决策支持系统的研究思路及系统实现的技术路线，采用Database Desktop来设计系统中的知识库、模型库和数据库。以数据库为基础的系统，有助于系统对知识、模型和相关数据的管理。对系统决策的过程采用基于数据库的方法进行编写，解决了温室作物生长智能决策过程中推理困难的问题，同时提高了决策的准确程度。经实际运用达到了预期的效果。     

Growth,yield and soil water extraction of irrigated and dryland peanuts in South Sulawesi,Indonesia

Summary Irrigation at 35 and 70 mm of pan evaporation applied during the pre and/or post early podfilling stages increased pod yield of Spanish peanuts (100 day maturity) three fold compared to a dryland crop. There was no difference in pod yield in crops receiving 12 compared to 6 irrigations. Soil water sampling immediately after irrigations on selected treatments revealed that infiltration of irrigation water was probably restricted to less than ca. 20 cm, a response which resulted in poor soil water replenishment and low irrigation efficiency (Fig. 3). Even though roots extracted soil water below the compaction layer which was at 20 cm severe crop water deficits had developed by the end of irrigation cycles during later but not early stages of growth. The dryland crop, which received no rainfall during the season, presumably extracted significant amounts of soil water at depths to and below 1.2 m (Fig. 3). Despite producing ca. 2.9 t ha^-1 of total dry matter yield, pod yield was extremely low (0.5 t ha^-1) arising from low pod numbers and high percentage of empty pods.This research was funded by the Australian Centre for International Agricultural Research (ACIAR-Project 8419) in collaboration with the Agency for Agricultural Research and Development (AARD).     

Crop coefficients for winter wheat in a sub-humid climate regime

Estimations of evapotranspiration (ET) from natural surfaces are used in a large number of applications such as agricultural water management and water resources planning. Lack of reliable, cheap and easy-to-use instruments, associated with the chaotic and varying nature of the meteorological and plant physiological factors influencing ET cause these estimations to be based on calculated values rather than the measured ones. The two-step approach where ET from a reference crop is calculated and multiplied by empirical crop coefficients to obtain ET from a crop has gained wide acceptance. Daily coefficients for a winter wheat crop growing under standard conditions, i.e. not short of water and growing under optimal agronomic conditions, were estimated for a cold sub-humid climate regime. One of the two methods used to estimate ET from a reference crop required net radiation (R_n) as input. Two sets of coefficients were used for calculating R_n. Weather data from a meteorological station was used to estimate R_n and ET from the reference crop. The winter wheat ET was measured using an eddy covariance system during the main parts of the growing seasons 2004 and 2005. The meteorological data and field measurements were quality controlled and discarded from the analysis if flagged for errors. Daily values of ET from the reference crop and winter wheat calculated from hourly values were used to calculate the crop coefficients. Average daily crop coefficients were in the 1.1–1.15 range during mid-season with standard deviations ranging from 0.13 to 0.23 for both years. These values exceed values used in some sub-humid climate regime studies, but agree well with values from the international literature.     

水泵零件强度校核软件数据模型的建立

水泵零件的强度校核是水泵设计的重要环节。为解决传统的水泵零件强度校核方法在精度、效率等方面的不足，采用数据智能读取与处理技术，在功能强大的VC＋＋6．0平台上，开发了实用的水泵零件强度校核软件，该软件由多个模块组成，各模块之间结构上相对独立但数据参数实现共享。零件强度校核的主要操作对象是计算过程中的各种数据，在对这些数据的来源进行分析的基础上建立了逻辑清楚、运行可靠的数据模型，研究了模型中重要数据的实现方法。材料参数的读取采用功能强大的ADO接口从数据库文件中直接读取的方法。软件的实际运行结果表明，该数据模型是稳定、合理、可靠的。     

农业干旱卫星遥感监测与预测研究进展

干旱是影响农业生产的主要气候因素。传统的农业干旱监测主要是基于气象和水文数据,虽然能提供监测点上较为精确的干旱监测结果,但是在监测面上的农业干旱时,仍存在一定的局限。遥感技术的快速发展,尤其是目前在轨的卫星传感器感测的电磁波段涵盖了可见光、近红外、热红外和微波等波段,为区域尺度农业干旱监测提供了新的手段。充分利用卫星遥感数据获得的丰富地表信息进行农业干旱监测和预测具有重要的研究意义。本文从遥感指数方法、土壤含水量方法和作物需水量方法三个方面阐述了基于卫星遥感的农业干旱监测研究进展。农业干旱预测是在干旱监测的基础上进行时间轴的预测,本文在总结干旱监测进展的基础上,进一步简述了以干旱指数方法和作物生长模型方法为主的农业干旱预测研究进展。     

Use of available information at a European level to construct crop nitrogen response curves for the regions of the EU

Nowadays European agriculture is evolving in a context where policy-making and environmental concerns play a key role. To better assess agro-environmental policies, the AROPAj agricultural supply model needs to take into account the technical characteristics of crop management for different farms. A method to build up specific relationships between yield and nitrogen fertilization that takes into account agronomic techniques is proposed in this paper. The nitrogen response curve is based on an exponential function that integrates economic properties consistently from an agronomic point of view. In AROPAj, individual production systems (farm types) do not have a given location within a specified region and in databases technical information is scarce. The method involves determining technical and physical characteristics, inputs that allow the STICS crop model to assess the yield response to nitrogen of each crop on every farm type. From this information, a nitrogen response curve can be drawn up for each crop of each one of the farms. It can take into account both nitrogen from purchased fertilizer and nitrogen from animal effluents produced on farm. The method was designed to be adaptable to any European region, and tests carried out on two French regions covering a wide range of situations (crops, soils, climates and techniques) showed it was able to cope with varying prices and environments. The agronomic consistency of STICS inputs and curve shapes was also checked. When incorporated into the AROPAj economic model, the response curves can be used to render farms more sensitive to agricultural policy scenarios, by allowing their optimal fertilization level to be adjusted.     

从2019年中国国际农机展看播种机技术特点及发展趋势

播种机是种植机械中比较重要的产品类型，是作物实现种植机械化的重要装备支撑，其技术发展水平直接决定了种植机械化进展。该文以2019年中国国际农业机械化展览会上展出的播种机为研究对象，分析典型产品的技术特点，总结发展趋势，为相关科研单位和生产企业研发播种机提供参考。      

查询分页技术在农副产品加工数据库设计中的应用

分页是数据库设计中的一项技术，许多Web应用程序用它来浏览大量记录。本文以农副产品加工品质数据库系统设计为例，介绍在数据库查询中基于ADO存取方式的分页技术的实现方法。