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.     

The Economic Impact of Site-Specific Weed Control

In order to evaluate economic and ecological benefits, site-specific weed control was realised in a 4-year experiment on five fields with a GPS-guided sprayer. An average of 54% of the herbicides could be saved. Savings were strongly dependent on crop and year. For grass weed herbicides, the savings were 90% in winter cereals, 78% in maize, and 36% in sugar beet. For herbicides against broadleaf weeds, 60% were saved in winter cereals, 11% in maize, and 41% in sugar beet. The monetary savings resulting from the reduction in herbicide use varied between the crops, depending on the amount of herbicides saved and the price of the herbicides. In maize, savings of 42euro/ha were realised, in winter wheat of 32euro/ha, in winter barley of 27euro/ha and in sugar beet of 20euro/ha. Large sections of the fields needed herbicide treatment significantly less frequently. In those areas where weed density remained below the weed control threshold, flora and fauna were allowed to establish largely without disturbance.     

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.     

Efficacy of Grid and Zone Soil Sampling Approaches for Site-Specific Assessment of Phosphorus,Potassium, pH,and Organic Matter

Within-field variability of plant-available nutrients often results in different fertilizer requirements across a field. There is uncertainty concerning the efficacy of alternative sampling strategies suitable for site-specific management. This study compared various soil sampling approaches for P, K, pH, and organic matter (OM) in eight agricultural fields. Soil samples were collected using an intensive 0.2-ha grid-point procedure, and were used to compare less intensive sampling approaches. The approaches were based on 1.2–1.6-ha grid cells (Grid), soil series of digitized soil survey maps (SSM), soil series of detailed soil survey (1:12,000 scale) maps, elevation zones, and management zones based on various information layers (ZS). The approaches varied in reducing the within-unit soil-test variability and maximizing mean soil-test values across sampling units, but none was superior across all fields and nutrients. All approaches were less efficient for P and K than for pH or OM. The Grid and ZS approach were the most effective across all nutrients and fields. However, the Grid approach was more effective for P, the Grid and ZS approaches were better for K and pH, and the SSM and ZS approaches were better for OM. The ZS approach often resulted in fewer sampling zones than the Grid approach, which implies lower soil testing costs for producers, but required more knowledge and subjective judgement than a Grid approach to adapt it to field-specific conditions.     

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。     

Development of an Image Processing System and a Fuzzy Algorithm for Site-Specific Herbicide Applications

In precision farming, image analysis techniques can aid farmers in the site-specific application of herbicides, and thus lower the risk of soil and water pollution by reducing the amount of chemicals applied. Using weed maps built with image analysis techniques, farmers can learn about the weed distribution within the crop. In this study, a digital camera was used to take a series of grid-based images covering the soil between rows of corn in a field in southwestern Quebec in May of 1999. Weed coverage was determined from each image using a greenness method in which the red, green, and blue intensities of each pixel were compared. Weed coverage and weed patchiness were estimated based on the percent of greenness area in the images. This information was used to create a weed map. Using weed coverage and weed patchiness as inputs, a fuzzy logic model was developed for use in determining site-specific herbicide application rates. A herbicide application map was then created for further evaluation of herbicide application strategy. Simulations indicated that significant amounts of herbicide could be saved using this approach.     

实时实地氮肥管理对水稻产量和稻米品质的影响

【目的】探讨实时实地氮肥管理对水稻产量和品质的影响。【方法】试验于2004和2005年在大田条件下，以两优培九、汕优63为材料研究了不同叶绿素仪（SPAD）预设阈值指导下的实时实地氮肥管理方式的产量与产量形成以及相应的稻米品质特性。【结果】在实时氮肥管理（RTNM）模式下，两优培九和汕优63各施氮处理比不施氮处理增产幅度分别达21.12%～57.65%和15.00%～31.18%。在实地氮肥管理（SSNM）模式下，两优培九和汕优63 SSNM处理比不施氮小区增产幅度分别达45.44%～50.71%和28.53%～32.40%。两优培九SPAD阈值分别由34～45的RTNM模式下，当SPAD阈值介于38～41之间时（氮肥用量120～165 kgN•ha-1）可以改善稻米的外观品质和加工品质；汕优63则以SPAD阈值36～39（氮肥用量：120～165 kgN•ha-1）范围内有利于改善米质。SSNM模式下以SPAD施肥阈值为37-39（氮肥用量130 kgN•ha-1）进行氮肥运筹能显著改善两优培九的加工品质、外观品质和营养品质；SSNM模式下汕优63以SPAD阈值为35～37时稻米品质相对较好，同时产量也比较高。【结论】实时实地氮肥管理能较好地协调水稻产量和品质的关系，关键措施是依据品种特性确定适宜的预设SPAD阈值。在本试验条件下，实时实地氮肥管理模式两优培九以SPAD 38～39、汕优63以SPAD 35～37左右时能获得较高的产量和部分地改善米质，可以作为生产上应用实时实地氮肥管理时的推荐阈值。     

Participatory Environmental Management and its Framework of Group Decision Support System

Considering some drawbacks of the mainstream approach to environmental management (EM) ,the conception and basic idea of Participatory EM(PEM) are put forward. PEM possesses some main features and benefits that are superior to the mainstream approach ,but also faces the crucial constraint in decision-making. The dilemma can be effectively settled by applying an advanced decision-making support tool-group decision support system(GDSS). On the basis of recognizing the complex decision-making environment of PEM,this paper describes the components of GDSS for PEM (PEM-GDSS) and further discusses the basic requirement of PEM-GDSS.     

Cre/loxP位点特异性重组系统在植物中应用的研究进展

Cre/loxP位点特异性重组系统自发现以来,在植物基因重组领域得到了广泛应用,已成为提高转基因植物安全性的有效方法。本文介绍了该系统的基本概况及其在转基因植物表达载体构建方面的应用,尤其是在基因删除、定点整合、多基因表达以及杂种优势利用等方面的应用做了重点阐述。     

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。     

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。     

城市固体废弃物管理及规划决策支持系统开发

在全面分析城市固体废弃物管理和规划决策支持系统的需求状态和特点的基础上,采用软件工程的方法,面向用户完成了该决策系统的系统分析、系统设计及初步开发工作。该系统库包括数据库管理系统和模型库管理系统。数据库管理系统又包括堆肥处理库、填埋处理库、焚烧处理库和综合处理库;模型库管理系统又包括模型库、模型数据库和图形数据库。该决策系统具有人机交互、信息支持、模型辅助决策以及处理方案生成,模拟和评价等功能,并突出实用性、灵活性和可操作性。     

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.     

秸秆还田与实地氮肥管理对直播水稻产量、品质及氮肥利用的影响

 【目的】探讨麦秸秆还田与施氮技术对直播水稻产量、品质的影响及氮肥利用效率的表现。【方法】以直播粳稻扬粳9538为材料进行大田对比试验,设置麦秸还田与不还田、实地氮肥管理（SSNM）和农民习惯施肥法（FFP）等处理,测定水稻产量、品质及氮肥利用效率。【结果】无论是SSNM还是FFP,与秸秆未还田相比,秸秆还田降低了单位面积穗数,提高了每穗粒数、结实率与千粒重,增加了产量,改善了稻米的外观品质与蒸煮品质。与FFP相比,SSNM显著提高水稻产量,降低了稻米蛋白质含量,改善了稻米的食味性。秸秆还田结合SSNM增大了籽粒最大灌浆速率与平均灌浆速率,缩短了活跃灌浆期,增加了粒重,并提高了氮收获指数、氮肥吸收利用率、氮肥农学利用率、氮肥生理利用率和氮肥偏生产力。【结论】秸秆还田结合SSNM可增加产量,改善稻米品质,提高氮肥利用效率。