Performance evaluation of a crop/weed discriminating microsprayer

An intelligent real-time microspraying weed control system was developed. The system distinguishes between weed and crop plants and a herbicide (glyphosate) is selectively applied to the detected weed plants. The vision system captures 40 RGB images per second, each covering 140 mm by 105 mm with an image resolution of 800 × 600 pixels. From the captured images the forward velocity is estimated and the spraycommands for the microsprayer are calculated. Crop and weed plants are identified in the image, and weed plants are sprayed. Performance of the microsprayer system was evaluated under laboratory conditions simulating field conditions. A combination of maize (Zea mays L.), oilseed rape (Brassica napus L.) and scentless mayweed (Matricaria inodora L.) plants, in growth stage BBCH10, was placed in pots, which were then treated by the microspray system. Maize simulated crop plants, while the other species simulated weeds. The experiment were conducted at a velocity of 0.5 m/s. Two weeks after spraying, the fraction of injured plants was determined visually. None of the crop plants were harmed while 94% of the oilseed rape and 37% of the scentless mayweed plants were significantly limited in their growth. Given the size and shape of the scentless mayweed plants and the microsprayer geometry it was calculated that the microsprayer could only hit 64% of the scentless mayweed plants. The system was able to effectively control weeds larger than 11 mm × 11 mm.     

田间杂草识别与除草技术智能化研究进展

随着计算机与电子技术的发展,田间杂草识别与除草技术逐步走向智能化,自动除草系统成为国内外研究热点。本文对组成田间杂草识别与自动除草系统的4个主要模块(系统导航模块、图像采集与处理模块、杂草识别模块和除草控制模块)分别进行了综述和分析,并指出目前研究中存在的问题及今后努力的方向。     

蟹塘梳草船驱动系统设计与试验

水草管理是河蟹养殖的重要环节,为降低水草收集设备操控劳动强度,降低人员使用量,研发梳草船的风机驱动系统。该驱动系统主要由风机叶片、防护装置、支架、电机、减速传动和防水密封罩等组成。通过CFD流体仿真计算并验证实体船的阻力情况,进行风机选型,其额定功率为1 100 W,工作电压48 V,叶片最大宽度100 mm,叶根倾斜角28°,设计具有自锁功能的转向系统。使用该驱动系统在河蟹养殖塘进行测试表明：48 V/24 Ah动力电池下其连续工作时间为1.5 h;无水草情况下空载和满载船速分别为1.14和0.43 m/s;轻度水草（水草顶端距离水面>3 cm且<8 cm）情况下空载和满载的最大船速分别为1.06和0.26 m/s;密集水草（水草顶端距离水面≤3 cm）情况下空载和满载的最大船速分别为0.71和0.12 m/s,同时可以保持前进姿态持续打捞水草;平均转弯半径1.2 m。现场应用表明该驱动系统满足蟹塘实际水草环境下梳草船的驱动需求,单位时间内与人工清理水草质量相比提高94.3%,为实现自动化水草管理打下了基础。     

茶园不同控草措施效果比较

[目的]探究不同茶园杂草防控措施的效果,寻找出成本低、效果佳、无污染的除草方式,为防控茶园草害发生及指导茶农科学除草提供技术支撑.[方法]以茶树自然生长为对照(CK),设套种绿豆(生物竞争)、人工除草(人工铲除)、剪枝覆盖(物理抑制)及喷施除草醋(化学清除)等4种不同控草处理,通过观测不同处理杂草数量、种类及株高等,计算杂草多样性指数,比较不同处理的杂草防除效果.[结果]试验区茶园共滋生杂草13科20属20种,4种不同控草措施对茶园杂草种类、数量、密度和株高均有不同程度的影响,茶园杂草种类减少1~8种,数量减幅16.62%~89.06%,密度抑制幅度4.18%~100.00%,除套种绿豆处理下个别草种株高呈现出增高的趋势外,其余处理对茶园杂草株高有明显的抑制作用.综合比较得出茶园杂草防控效果依次为除草醋>剪枝覆盖>人工除草>套种绿豆.[结论]喷施除草醋和剪枝覆盖处理对茶园杂草防控效果表现尤为突出,可在当前茶园生产实际中大力推广应用.     

水泥混凝土轴心受压应变的分布曲线

对3组共9个水泥混凝土棱柱体试件(150mm×150mm×300mm)进行逐级加载试验,研究水泥混凝土棱柱体试件轴心受压时接近试验机压头位置以及其他各截面纵向应变的分布状况,得到不同荷载作用下的各截面应变分布曲线.分析水泥混凝土棱柱体试件不同位置在荷载逐渐加大情况下的应变分布规律,进而得到应变分布曲线方程.     

Real-time image processing for crop/weed discrimination in maize fields

This paper presents a computer vision system that successfully discriminates between weed patches and crop rows under uncontrolled lighting in real-time. The system consists of two independent subsystems, a fast image processing delivering results in real-time (Fast Image Processing, FIP), and a slower and more accurate processing (Robust Crop Row Detection, RCRD) that is used to correct the first subsystem’s mistakes. This combination produces a system that achieves very good results under a wide variety of conditions. Tested on several maize videos taken of different fields and during different years, the system successfully detects an average of 95% of weeds and 80% of crops under different illumination, soil humidity and weed/crop growth conditions. Moreover, the system has been shown to produce acceptable results even under very difficult conditions, such as in the presence of dramatic sowing errors or abrupt camera movements. The computer vision system has been developed for integration into a treatment system because the ideal setup for any weed sprayer system would include a tool that could provide information on the weeds and crops present at each point in real-time, while the tractor mounting the spraying bar is moving.     

Evaluation of an autonomous GPS-based system for intra-row weed control by assessing the tilled area

An automatic tillage system for inter- and intra-row weed control based on real-time kinematic GPS navigation and control has been used to address the problem of mechanically removing weeds within rows of precision seeded crops. The system comprised a side-shifting frame with an attached tine-rotor (cycloid hoe) with eight sigmoid-shaped, vertically directed tines. The individual tines can be released for individual rotation in order to avoid collision with geo-referenced crop plants. The system navigated with reference to pre-defined waypoints for tillage parallel to crop rows and around individual crop plants. The system evaluation was based on quantification of treated areas for uprooting and burial and the corresponding prediction of weed control efficiencies. A single pass of an 80 mm wide row band provided tillage of 30–49% of the intra-row area, with highest coverage at a speed of 0.32 m s⁻¹ and at even plant spacing. A double pass, once on each side of the row in opposite directions, provided higher soil disturbance intensity and resulted in tillage of 31–58% of the intra-row area with highest coverage at a speed of 0.32 m s⁻¹. The intra-row weed control effect was predicted to be up to 20% for a single pass and up to 29% for a 2-way pass treatment both at the white thread to the two-leaf stage of weeds. The result of the prediction is of crucial importance for the considerations of tool designs at the current conceptual stage of the system.     

海南省南红稻田杂草群落的模糊聚类分析

采用模糊聚类法对海南省南红稻田要草群落进行研究,以优势度作为因子归并样方,得到样方树图,并结合实际结果,讨论了杂草群落的成层现象,结果可作为杂草防除的依据。     

辽宁东部山区几种主要森林植被类型土壤矿质层蓄水能力分析

对辽宁东部山区具有代表性的油松林、落叶松林、红松林、柞木林、杂木林及灌丛6种植被类型的土壤蓄水能力及其影响因素进行了比较研究。结果表明 ,各植被类型80cm土层的总蓄水能力为362.0～422.2mm,平均值为387.2mm ;80cm土层的有效蓄水能力为102.4～182.2mm,平均值为156.5mm,都表现为阔叶林大于针叶林,灌丛居于中间。棕壤和暗棕壤无论是总蓄水能力还是有效蓄水能力都表现出阔叶林大于针叶林。植被类型、土壤种类及土壤层次对非毛管孔隙度有显著影响。植被类型对非毛管孔隙度的作用特点是阔叶林大于针叶林,灌丛居于中间 ;土壤类型的作用特点是棕壤大于暗棕壤 ;土壤层次的作用特点是A层>B层>C层。本研究对于科学地评价该地区水源涵养林的水文效益,指导水源涵养林体系建设具有重要意义     

Guidance of a Forage Harvester with GPS

Precision agriculture requires automatic control of agricultural machinery in order to cope with the large amount of information which has to be applied during site specific field work. The driver is occupied with operating and supervising the controlled and non-controlled implements as well as with vehicle guidance. Steering, in particular, is monotonous and tiring. This can result in reduced operation quality. This was the motivation to develop a concept of a guidance system for agricultural vehicles. A self-propelled forage harvester was the test vehicle for this research. The harvester was equipped with an automatic steering system. Real Time Kinematic Global Positioning System (RTK-GPS) was used as the only positioning sensor due to high absolute accuracy within the field and its high reliability. The system performance was investigated under various test conditions. Additionally a guidance-path-planning for swath harvesting operations was developed. Both the automatically steered forage harvester and the path planner could be examined under real field conditions. The standard deviation of the driving performance was better than 100 mm under all conditions. The swaths could be collected reliably with the automatically steered forage harvester.     

Evaluation of agronomic and economic benefits of using RTK-GPS-based auto-steer guidance systems for peanut digging operations

Increasing the peanut (Arachis hypogea L.) digger efficiency by accurate placement over the target rows could minimize damaged pods and yield losses. Producers have traditionally relied solely on tractor operator skills to harvest peanuts. However, as peanut production has shifted to new growing regions in the Southeast US, producers face difficulties digging peanuts under conventional and new management schemes. The present study aimed to: (i) determine the effect of row deviations (RD) of the digger from the target row on peanut yield and quality, and (ii) determine the economic value of using RTK auto-steer guidance systems to avoid tractor deviations during peanut harvest. The study consisted of a randomized complete block design of tillage [conventional (CT) and strip tillage (ST)], row patterns [single (SR) and twin (TWR)] and row deviation (RD_0 mm, RD_90 mm, and RD_180 mm). The RD_90 mm and RD_180 mm treatments exemplify manual driving deviations compared to using an RTK auto-steer guidance system (RD_0 mm). Higher yields and higher net returns resulted from using the RTK auto-steer guidance system. Data showed that for every 20 mm row deviation, an average of 186 kg ha^?1 yield loss can be expected. Overall, yield was higher for the conventional tillage and twin row pattern treatments compared to the other treatments. Yield losses for the SR-CT treatment were higher as the row deviation increased compared with the TWR-CT treatment. In contrast, higher yield losses for TWR-ST compared to SR-ST were observed when deviations of 180 mm occurred instead of digging using the RTK auto-steer guidance system. While a farmer using an RTK auto-steer guidance system with an accuracy within 25 mm (RD_0 mm treatment) could potentially expect additional net returns of between 94 and 404 $ ha^?1 compared to those from row deviations of 90 mm, higher net returns of between 323 and 695 $ ha^?1 could be perceived if the guidance system is used instead of having row deviations of 180 mm. Therefore, the use of RTK auto-steer guidance system will allow growers to capitalize on the increases in yield potential by implementing changes in tillage and row patterns as those evaluated in this study.     

油-棉连作棉田油菜秸秆覆盖对棉田杂草发生及土壤杂草种子库的动态影响

在安徽省沿江棉区开展了油菜秸秆覆盖对棉田杂草发生、棉花生长及土壤杂草种子库影响的研究。结果表明,随着油菜秸秆覆盖量的增加,对棉田杂草的抑制效果增强。与未覆盖秸秆且不除草处理相比较,7000Kg/hm²秸秆覆盖量处理棉花单株铃数和子棉产量显著提高。7000Kg/hm²秸秆覆盖量处理在覆盖后30d、60d和120d逐步减少0-20cm土层杂草种子库密度,与全程除草剂处理较一致;随着覆盖量减少,对0-20cm土层杂草种子库密度降低幅度减小。全程除草剂处理降低0-5cm土层杂草种子库多样性,而油菜秸秆覆盖则可能增加0-5cm土层的杂草种子库多样性。3500Kg/hm²覆盖量+秸秆覆盖30d后喷施除草剂处理的抑草效果和增产效果与全程除草剂处理一致。因此,在安徽省沿江棉区油-棉连作棉田推荐使用3500Kg/hm²油菜秸秆覆盖量+秸秆覆盖30d后喷施除草剂。     

从土壤种子库角度探讨草坪杂草的可持续管理

土壤杂草种子库是草坪杂草发生危害的主要根源,种子库的动态变化规律对于杂草的综合管理具有非常重要的意义。本文对土壤杂草种子库进行了论述,同时提出在草坪建植与养护管理过程中实行基于杂草种子库调控的草坪杂草综合治理策略,即合理地运用物理的、化学的、生物的、生态学的手段和方法,有机的组合成“断源、截流、竭库”的杂草综合管理体系,将有害杂草有效的控制在生态经济阈值水平之下,实现草坪杂草的可持续管理。     

三种植物在不同肥力下对紫茎泽兰的生态控制效果

以狗尾草、黑麦草、白三叶为材料研究了混栽其中的紫茎泽兰在不同肥力条件下的生长状况。结果表明,黑麦草和白三叶在高肥力的条件下对紫茎泽兰的控制效果最好,中肥力次之,低肥力最差;而狗尾草在三种肥力条件下最终控制效果基本相同,基本上消灭了紫茎泽兰。因此可以建议,在土壤肥力较差时,可以通过施肥等措施来加强黑麦草和白三叶的竞争力,从而达到控制紫茎泽兰的作用。     

交通荷载下管道疲劳寿命的模糊可靠度方法

以受交通荷载作用的埋地管道为研究对象，认为受交通载荷作用下管道的失效是一个模糊随机事件。考虑交通载荷的非平稳作用特点，基于模糊理论，在合理选取隶属函数的基础上，结合可靠度分析方法对交通荷载作用下管道的疲劳寿命进行了计算，提出了一套简便方法，从而为交通荷载下管道系统的可靠性设计计算提供了一种明确的分析方法和思路。     

不同施氮水平和杂草清除时间对半湿润地区农田氮素利用及产量的影响

在半湿润地区中等肥力土垫旱耕人为土上进行田间试验,通过对冬小麦不同生育期杂草和作物样品的采集与分析,研究不同施肥及杂草处理对氮肥肥效的影响。结果表明:作物吸氮量随施氮量增加而增加,杂草吸氮量随吸氮量增加而降低;在不同杂草处理全生育期不清除杂草(A)、越冬前清除杂草(B)、返青期清除杂草(C)和拔节期清除杂草(D)的各个处理中,A、B、C和D杂草吸氮量分别占农田植物(作物 杂草)地上部分总吸氮量的1.98%、1.39%、3.99%和3.82%。籽粒产量随施氮量增加而增加,施氮量为135 kg N.hm-2时产量最高,达5 645.1 kg.hm-2,施氮量高于135 kg N.hm-2时,产量趋于稳定。氮肥利用率、氮肥利用效率、氮肥农学效率和氮肥生理效率均随施氮量增加而降低;从不同杂草处理看,以全生育期不清除杂草处理氮肥利用率最高,达到43.8%,返青期清除杂草处理氮肥利用率最低,为26.3%,二者间差异达显著水平;氮肥利用效率以越冬期清除杂草处理最高,为42.8 kg.kg-1N,全生育期不清除杂草处理最低,为40.6kg.kg-1N;氮肥生理效率以返青期清除杂草处理最高,为57.5 kg.kg-1N,显著高于其他杂草处理。综合氮效率及产量效率,小麦农田杂草处理时间应该相对较早,以越冬期和返青期清除杂草较好。     

Biological Control of Yellow Nutsedge with the Indigenous Rust Fungus Puccinia canaliculata

Yellow nutsedge (Cyperus esculentus L.) is a serious weed problem in the United States and other countries. An indigenous rust fungus [Puccinia canaliculata (Schw.) Lagerh.], pathogenic on yellow nutsedge, was released in early spring as a potential biological control agent. The fungus inhibited nutsedge flowering and new tuber formation. The fungus also dehydrated and killed nutsedge plants. The successful control of yellow nutsedge by a rust epiphytotic under experimental conditions demonstrates the potential use of the rust in an integrated weed management system.     

Curved and straight crop row detection by accumulation of green pixels from images in maize fields

This study proposes a new method for detecting curved and straight crop rows in images captured in maize fields during the initial growth stages of crop and weed plants. The images were obtained under perspective projection with a camera installed onboard and conveniently arranged at the front of a tractor. The final goal was the identification of the crop rows which are crucial for precise autonomous guidance and site-specific treatments, including weed removal based on the identification of plants outside the crop rows. Image quality is affected by uncontrolled lighting conditions in outdoor agricultural environments and by gaps in the crop rows (due to lack of germination or defects during planting). Also, different plants heights and volumes occur due to different growth stages affecting the crop row detection process. The proposed method was designed with the required robustness to cope with the above undesirable situations and it consists of three sequentially linked phases: (i) image segmentation, (ii) identification of starting points and (iii) crop row detection. The main contribution is the ability of the method to detect curved crop rows as well as straights rows even with irregular inter-row spaces. The method performance has been tested in terms of accuracy and time processing.     

不同耕作模式对大豆田土壤杂草种子库的影响

[目的]明确不同耕作模式对大豆田土壤杂草种子库的影响。[方法]采用杂草种子萌发法,调查玉米大豆轮作区翻耕和免耕2种耕作模式下大豆田0~30 cm土层土壤杂草种子库组成及特征。[结果]2013—2015年调查统计结果表明,翻耕大豆田杂草共有16科28种,免耕大豆田杂草共有15科26种,有22种杂草在翻耕和免耕大豆田均有分布。翻耕田主要优势杂草为稗草、铁苋菜、龙葵、藜和委陵菜,免耕田主要优势杂草为龙葵、铁苋菜、稗草、藜和马唐,杂草类型以阔叶杂草为主,禾本科杂草较少。翻耕大豆田杂草种子库密度为3 248.2粒/m2,主要分布在0~5、15~20、20~25 cm土层,其中稗草的密度和相对优势度最高;免耕大豆田杂草种子库密度为3 181.5粒/m2,主要分布在0~5、20~25、25~30 cm土层,其中龙葵密度和相对优势度最高。不同耕作模式优势杂草在土层中的分布有一定差别,稗草在翻耕田主要分布于0~5、10~15、20~25 cm土层,而在免耕田主要分布于20~25 cm土层;龙葵在翻耕田主要分布于5~10、20~25 cm土层,而在免耕田主要分布于20~25 cm土层。[结论]免耕和翻耕对大豆田杂草种子库密度影响不大,不同耕作模式对杂草相对优势度和土壤中的垂直分布有一定影响。     

测算辽东山区主要林分类型的蒸发散量

本试验运用固定标准地观测的方法测定辽东山区几种主要林分类型的蒸发散量,根据布兰尼-尼里德尔模型推算的后楼水库集水区邻域范围内的年土壤和枯落物水分蒸发量分别为落叶松幼龄林720 mm/a、落叶松中龄林751 mm/a,红松幼龄林762 mm/a、红松中龄林826 mm/a、柞树林677 mm/a、杂木林741 mm/a.影响单位面积蒸发量的主要因子为地表枯落物量,同时蒸发量又与郁闭度呈弱的负相关关系,地表至20 cm的表层土壤的水分蒸发量约占总蒸发量的绝大部分;各个林分类型间的蒸腾量差异显著.