Crop/Weed Outcomes from Site-Specific and Uniform Soil-Applied Herbicide Applications

While uniform broadcast application (BC) of soil-applied herbicides is the norm, advances in geospatial technologies have enabled the deployment of site-specific herbicide application (SS). Since there are several, largely-untested decision rules for SS herbicide use, the objective of this work was to evaluate crop/weed outcomes and isoxaflutole use for a number of BC and SS strategies. Field experiments were established where isoxaflutole dose response functions were quantified from early-season Zea mays (L.), Sorghum bicolor (L.) Moench., and Abutilon theophrasti Medic. response data at multiple plots (64 in 1999; 62 in 2000) throughout a variable field. These data were then used to infer crop and weed outcomes from simulated application strategies. While BC and SS strategies that relied on the product label were similar in terms of total herbicide use, extent of crop tolerance, and A. theophrasti efficacy, the SS strategy resulted in a significant redistribution of herbicide. Using biologically effective doses (ED) resulted in the highest efficacy and herbicide use was highly species-dependent. By using a historical weed map of the field to guide herbicide application, herbicide use could be reduced some 20–48% when following the product label where seedlings were present, or >90% when using the ED for A. theophrasti. In order to maximize the potential agronomic benefits of SS, biological and spatial information of both the weed and soil should be taken into account.An erratum to this article can be found at     

Two-Year Weed Seedling Population Responses to a Post-Emergent Method of Site-Specific Weed Management

Field experiments were conducted to determine how a site-specific weed management practice in Zea mays L. influenced the numerical and spatial distribution of a naturally occurring weed infestation in Z. mays and the succeeding Beta vulgaris L. crop. Compared to conventional broadcast herbicide applications, site-specific herbicide applications reduced herbicide load by 11.5 and 98.0% in two separate Z. mays fields. The broad range in outcomes was attributed to the spatial aggregation and density of target weed populations. While herbicide use was successfully reduced at field locations with low weed density, most survivors of multiple control tactics were in locations with the highest initial density. A greater understanding of interactions between weed management and weed density would increase the likelihood that site-specific weed management offers long-term improvements over conventional approaches.     

Site-Specific Weed Control in Maize,Sugar Beet,Winter Wheat,and Winter Barley

A four-year study of site-specific weed control is presented in this paper. Weed seedling distribution was sampled and mapped prior to and after post-emergence herbicide application in four fields planted with maize, sugar beets, winter wheat and winter barley, rotating on one site. Herbicides and other weed control strategies were applied site-specifically according to the spatial variation of weed populations. Different decision algorithms were used for chemical weed control methods in each crop. A weed treatment map was created to direct location and dosage of herbicide application. The sprayer was coupled with a differential Global Positioning System (DGPS). The solenoid valves of the sprayer were opened automatically when the tractor entered a weed patch characterized in the weed treatment map. For site specific herbicide application, a patch sprayer was developed that allowed variable rate application and the selective control of each section of the spray boom.     

Soil and Weed Survey for Spatially Variable Herbicide Application on Railways

Weed control on railways is frequently done by herbicide application, using large amounts of chemicals and labour. Only a few hectares of surface area on a railway can be many kilometres long so high levels of spatial variability of soils and weeds are expected. Railway sprayers use similar technology to crop sprayers so it is possible to adopt concepts from precision agriculture for weed control. The objective of this study was to evaluate spatial variability of soils and weeds on railways in order to define weed control strategies and basic characteristics of a railway sprayer. This work is part of a research project aiming at the development of a system for spatially variable herbicide application on railways. Soil and weed data were collected from five different railway companies in Brazil. These data were used to simulate treatment maps based on weed control strategies and to estimate technical requirements for spatially variable herbicide application. The results showed that soil and weed survey gave important information for defining weed control strategies and spraying equipment. The sprayer must treat the three swaths (left, central and right parts of the railway surface) separately applying at least two different herbicides at the same time. On average, a variable dose rate application based on the treatment maps generated in this work could save up to 59% of herbicides.     

抗药性杂草产生原因及治理策略

分析了长时间或多次使用一类或一种除草剂及使用作用靶标相同的除草剂致使杂草抗药性产生的原因,同时指出除草剂和杂草的特性也对杂草的抗性产生影响。提出了治理杂草抗性的措施：以预防为主,多种手段相结合的方式延缓和治理杂草抗药性的产生。     

林业及生态系统管理决策支持系统研究综述

概述了决策支持系统的概念、结构组成，以及与MIS，ES的区别与联系，提出了DSS的未来发展方向。详细评价了国内外林业及生态系统管理决策支持系统的研究与应用情况。     

新靶标铁苋菜在除草化合物筛选研究中的应用

铁苋菜具有特殊的生物学特性,属于旱田难防杂草。采用商品化除草剂硝磺草酮及巴佰金对铁苋菜进行室内防除试验,同时验证与硝磺草酮及巴佰金结构类似的新化合物对其的防除活性。结果表明,结构类似的除草化合物对铁苋菜的防除活性较为接近;铁苋菜作为新的生测靶标,可应用于化合物除草活性生测筛选研究。     

Evaluation of the Accuracy of a Central Iowa Soil Survey and Implications for Precision Soil Management

The movement towards precision agriculture has led to calls for soil maps that are more detailed and accurate than those offered in standard NCSS soil surveys. Studies have shown that soil variability can be greater than depicted in soil surveys; in fact, delineations that contain at least 50% of the soil mapped are considered satisfactory for soil survey purposes. Lacustrine plains are relatively flat and often have parent materials with uniform properties. Because soils are usually mapped using soil–landform relationships one might expect soil maps in these areas to be less accurate than average; it is difficult to delineate between map units using soil–landform relationships in such subtle landscapes. We grid-mapped a field containing lacustrine-derived soils in central Iowa and used the grid to evaluate the soil survey for accuracy. Two major and two minor soils, as determined by the area they occupy in the field, were present. For the field as a whole, the two major soils were correctly identified by the soil survey at least 63% of the time. The two minor soils were correctly identified 33% of the time or less by the soil survey. Large-scale soil mapping is expensive because of the time involved to create them in the field and in the office. Therefore, it is only economically beneficial to produce a detailed map if the map leads to significant alterations in the way a field is managed. In fields that may have uniform soil properties, it may be more cost-effective to conduct a reconnaissance survey first and then decide if more detailed mapping is required.     

Comparison of Estimated Costs and Benefits of Site-Specific Versus Uniform Management for the Bean Leaf Beetle in Soybean

Six soybean, Glycine max (L.) Merrill, fields were examined to compare estimated costs and benefits for uniform and site-specific management (SSM) programs for the bean leaf beetle, Cerotoma trifurcata (Forster). Beetle counts and soybean yield were field-collected, insecticide and sampling costs were estimated. In five fields, site-specific management produced only slightly greater return. The inclusion of sampling costs in each scenario resulted in higher return for the uniform scenario. The uniform management scenario estimated pest pressure as well as the site-specific scenario when beetle populations were high or low. In one field with moderate pest pressure, the SSM scenario would have increased insecticide use. The estimations in this study are based on hypothetical scenarios and the application equipment to target insecticides based on map coordinates is not readily available. The economic estimations provide examples of current limitations of site-specific management that need to be addressed before this technology becomes valuable for soybean insect management.     

A Knowledge Model- and Growth Model-Based Decision Support System for Wheat Management

By applying the system analysis principle and mathematical modeling technique to knowledge expression system for crop cultural management, the fundamental relationships and quantitative algorithms of wheat growth and management indices to variety types, ecological environments and production levels were analysed and extracted, and a dynamic knowledge model with temporal and spatial characters for wheat management (WheatKnow) was developed. By adopting the soft component characteristics as non language rele vance, re-utilization and portable system maintenance, and by further integrating the wheat growth simulation model (WheatGrow) and intelligent system for wheat management, a comprehensive and digital knowledge model, growth model and component-based decision support system for wheat management (MBDSSWM) was established on the platforms of Visual C++ and Visual Basic. The MBDSSWM realized the effective integration and coupling of the prediction and decision-making functions for digital crop management.     

Effects of Site-Specific Nitrogen Management on Yield and Dry Matter Accumulation of Rice from Cold Areas of Northeastern China

The effects of yield increase and mechanism of site-specific nitrogen management （SSNM） in five rice varieties from cold areas of northeastern China were studied. Plot experiment for critical SPAD value and experiments of two fertilization methods, SSNM and farmer＇s fertilization practice （FFP） were conducted to study their effects on the quality and dry matter accumulation of rice population, as well as N uptake. Compared with FFP, SSNM significantly decreased the average N rate by 33.8%, significantly increased average ear-bearing tiller rate and LAI for grain-filling stage by 12.3% and 14.1-27.6%, correspondingly, improved dry matter weight and N uptake after heading period by 4.3-29.1% and 11.8-55.1% （P 〈 0.05）, and heightened recovery efficiency and agronomic efficiency by 38.5-133.4% （P 〈 0.05） and 39.8-194.3% （P 〈 0.05）, respectively, as well as increased the average yield by 9.8% in 2004 and 2005. The results indicated that the accumulation rate of dry matter and N increased the rice yield and N use efficiency, because of improving rice population quality and increasing LAI after heading period.     

基于RM、RS与GIS的小流域综合治理决策支持系统

为了给探索小流域信息化管理和科学决策的面向对象的软件工程技术以及多媒体和网络技术提供方法和途径,采用Visual Basic6.0作为开发工具,以区域管理软件Region Manager V5.5(RM)为开发平台,通过遥感系统(RS)、地理信息系统(GIS)与专家系统松耦合的方式,开发出小流域综合治理决策支持系统(DSS);可应用于土地资源管理、林业资源管理、水土保持、荒漠化防治与监测、生态农业开发、草场管理、林业生态工程规划设计与监测评价等领域,有助于实现办公自动化和决策科学化。     

Comparison of Different Sampling Scales to Estimate Weed Populations in three Soybean Fields

A study was conducted to evaluate the accuracy of different weed sampling scales to accurately describe populations in soybean. Three soybean fields were sampled at 8 and 6 weeks after planting in 1998 and 1999, respectively. All weed species were counted on a 10 m grid, using a 0.58-m² quadrat. Data were eliminated from the original 10 m grid sample of weeds for each field to develop 40 m, 60 m, and 80 m independent data sets. Distribution and population maps were interpolated using an inverse distance weighted method. Data were extracted from the interpolated maps at known coordinates so that the observed population and the predicted population could be compared. The 10 m grid served as a standard to which all others were compared. No differences in population accuracies between each scale were detected when results were compared on a per weed basis, except when weed populations were very high, generally exceeding 400 plants ha^–1. When the weed density was not at an extreme, the results from these data indicate the ability to describe or account for the weed population fairly accurately, when using coarser grid sizes. These results also suggest that when using a regular grid coordinate system as the sampling structure, an increase from a 10 m scale to an 80 m scale will not cause a significant loss of information when weed populations were not extreme and will provide the necessary information for making suitable weed treatment decisions. However, some small weed patches were not detected with the coarser sampling scales, and the larger sampling scales would not meet their needs if the producers objective is complete control of a species.     

双季稻田生态系统信息管理的调控决策支持系统(DOREIDS)研究

阐述了DORIEDS的设计思想,整体设计,基本功能及展望,该系统是由综合调控系统（ICS）与专业调控系统（PCS）组成的双层结构,ICS是4个PCS的总平台,技术信息系统（作物技术措施知识库）,环境信息系统（环境信息数据库）,技术经济评价系统（20余种作物种植方式的数据库和模型库）以及RICAM 1．3（水稻生长发育预测模型）,DORIEDS的基本功能为：信息查询和情景分析;生长发育和产量形成进程的预测,优化农艺方案和应变决策的建议,新品种适应性的预估和杂交水稻制种的花期预测;水稻育种的理想株型的模拟,以及技术经济的评价。     

农业科研机构评价辅助支持系统构建研究

在明确了农业科研机构评价辅助支持系统的系统功能及性能要求的基础上提出了基于构件技术的构建方案,依照此构建方案对系统结构和功能进行介绍,详细描述了系统实现评价辅助服务的评价模型和关键技术,最后就该系统的应用提出对未来的展望。     

近自然森林经理计划体系技术应用示范

基于北京市一个示范区的实例,介绍在森林生态系统多功能可持续经营目标指导下的近自然森林经理计划技术体系及其4个技术要素的实现方法与具体应用。群落生境分析制图技术是支持森林经理空间区划和作业级类型计划的基本技术工具;森林发展类型设计技术为在“作业级”这个自然性质、动态特征和经营目标基本一致的经营空间单元层次上提供了长期稳定的目标森林设计模式;目标树作业方法是规定本经理期内对当前林分执行具体采伐和造林（补植）作业的技术模式;垂直结构导向的经营周期计划给出了从林分发生发展到最终利用全过程的作业计划。希望通过与操作实例结合提出的近自然森林经营计划体系,能成为在多功能经营目标下的新型森林作业法的一个典型参考案例。     

敏感性分析在林业经营决策中的应用

敏感性分断是项目投资中的一种风险分析技术。根据调查资料,分析了3个树种7个经营类型的总收益最佳值,在此基础上分别对影响总收益的造林成本、平均年成本、贴现率、价格做了敏感性分析。分析结果,总结规律,并在林业经营决策中提出了相应对策,以期降低经营风险。     

玉米精准作业智能空间决策支持系统的研究与应用

为解决玉米精准施肥、土壤肥力评价、地力等级分类和产量预测等问题,将具有空间信息处理功能的地理信息系统、具有空间信息分析功能的空间数据挖掘技术、人工智能领域中的专家系统技术与传统的信息管理系统、决策支持系统有效集成,并将GIS中的统计分析方法与数据可视化结合起来,研制了玉米精准作业智能空间决策支持系统。该系统极大提高了农业管理部门进行农业生产决策的能力。     

农业病虫草害图文知识服务系统的研发与应用

针对新农村植物保护工作需要,研制开发了＂农业病虫草害图文基础数据库＂＂合肥市农业病虫草害专家管理系统＂等网络软件,及植保类图书、课件、视频等植保信息产品,通过因特网等途径提供服务,为基层植保工作者、农技人员、农业企业、知识农民提供病虫草害知识检索和浏览。该系统的知识库高效灵活,软件系统傻瓜易用,服务手段更先进,适宜我国广大农村的发展和生产需求。     

林业网格化管理模式评价体系研究

为科学地评价林业网格化管理模式的绩效,在概述林业网格化管理模式和当前评价体系的基础上,提出了林业网格化管理模式评价体系。评价体系以管理区域、专业部门和管护员为对象,以月为周期,提出了22项基本指标和16项比率指标,采用内部评价和外部评价相结合的方法,提出了管理区域评价三级6项评价指标体系、专业部门评价二级6项评价指标体...