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1.
Wild blueberry producers apply fungicide uniformly without considering significant bare spots in the field. The wrong or over use of fungicide in bare spots results in an increased cost of production and threatens the environment. An automated prototype variable rate (VR) sprayer was used for spot-application (SA) of Chlorothalonil (Bravo®) fungicide in a wild blueberry field. Eighteen 6.1 m wide test tracks were selected in the field and bare spots were mapped using a real-time kinematics-global positioning system (RTK-GPS). Six plots were selected randomly for three different application rates. Water sensitive papers (WSP) were placed in foliage and bare spots in SA and uniform-application (UA) tracks. The percent area coverage (PAC) of WSP with both SA and UA in foliage and bare spot areas were calculated. Plant growth parameters were measured from all 108 randomly selected plots in SA, UA and control (CN) tracks for comparison. Plant images were taken over six selected plots in each of the 18 tracks. Images were analyzed using custom developed software to calculate the percentage of green pixels (PGP) for determining the effect of Bravo® on plant health. Fruit yield parameters were also measured from selected plots for comparison. Non-significance of the t test for SA versus UA plant targets’ PAC indicated that there was no significant bias in the SA with saving (9.90–51.22 %) and SA was accurate. Bravo® did not show any significant difference on plant growth parameters among SA, UA and CN. However, PGP, floral bud and harvestable yield of SA and UA were significantly increased over CN. Therefore, a VR sprayer could be used for SA of fungicides in wild blueberry cropping system to reduce chemical usage and maintain crop productivity.  相似文献   

2.
An essential part of the wild blueberry cropping system is the proper management of agrochemical inputs including herbicides, fungicides and insecticides. A machine vision system was developed and mounted on the rear sprayer boom 0.18 m in front of the sprayer nozzles capable of targeting the agrochemical application on an as-needed basis. The three-point hitch mounted sprayer featured 27 nozzles over a 13.7 m boom width and a storage tank capacity of 1135 l. Nine digital color cameras continually take images in real-time while computer software processes the images in 0.15 s to determine the target locations where the nozzles open and spray at speeds up to 1.77 m s?1. Two wild blueberry fields in central Nova Scotia were selected for smart sprayer performance testing with spot-application (SA) of agrochemical as compared to control and uniform application techniques. Chateau® herbicide was applied in a field with an infestation of hair cap moss. Spray droplet comparison showed moss patches were properly targeted using the smart sprayer. SA provided the same coverage performance as compared to uniform on the moss targets with herbicide application savings of 78.5% using the smart sprayer. Harvestable yield results were similar for all application tracks. TruPhos Magnesium and ZincMax foliar fertilizers were tank mixed with Bravo® and Proline® fungicides and applied to compare the difference of SA, control and uniform application. Results showed SA of foliar fertilizer and fungicide led to less premature leaf drop and increased the blueberry stem height, number of branches, stem diameter and fruit buds. SA of foliar fertilizer and fungicide also increased the percent of healthy wild blueberry plants by 57.8% and the harvestable yield by 137.8%. Fungicide application savings using the smart sprayer for SA were 11.6%.  相似文献   

3.
The wild blueberry industry is spending over $80 million CAD per year on agrochemicals for 93 000 ha under production in North America. A pressing need to reduce agro-chemical usage and production cost has resulted in the development of a smart sprayer for spot-application of agrochemicals in wild blueberry fields. This paper encompasses the economic analysis to determine the potential savings for spot-applications of agrochemicals using a smart sprayer. The economic analysis compared the smart sprayer with two other commercially available sprayers (basic and swath control). The swath control sprayer and smart sprayer both featured GPS auto-steer and boom section control to reduce over-spray in already applied areas based on GPS position. The basic sprayer used a foam marker for guidance with no swath control management. The smart sprayer featured a machine vision system that automatically detected target areas in the field further reducing agrochemical input by shutting individual nozzles off in non-target areas in the field. The cost analysis was performed to compare the different features of the sprayer technologies, i.e., base sprayer, additional technology, training, usage, repair and maintenance. The additional components installed on the smart sprayer were justified in terms of agrochemicals/water savings via spot-applications, tractor fuel and operator’s time. The application total cost was $2052 ha?1 using the basic sprayer, $1799 ha?1 using the swath control sprayer, and $1138 ha?1 using the smart sprayer over a 2 year production cycle of the selected fields that were used in this study. The payback period ranged from 2.0 years (60 ha field size) to 9.8 years (20 ha field size) using the swath control sprayer. The payback period ranged from 11 months (60 ha field size) to 3.5 years (20 ha field size) when using the smart sprayer. Results revealed that the smart sprayer had significant advantage from both an environmental and economic perspective over the other two sprayers.  相似文献   

4.
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.  相似文献   

5.
秸秆还田与氮肥管理对稻田杂草群落和水稻产量的影响   总被引：1，自引：1，他引：0  
为了研究秸秆还田和氮肥管理对稻油轮作夏季稻田杂草群落分布特征和水稻产量的影响,试验设5个处理：常规施肥NPK+秸秆不还田,N基追肥比例为6：2：2（F0NS,CK）;常规施肥NPK+秸秆全量还田,N基追肥比例为6：2：2（F0S）;常规施肥NPK+秸秆全量还田+秸秆腐解剂,N基追肥比例为6：2：2（F0SA）;常规施肥NPK+秸秆全量还田+秸秆腐解剂,N基追肥比例为7：2：1（F1SA）;常规施肥PK,N减量15%+秸秆全量还田+秸秆腐解剂,N基追肥比例为6：2：2（F2SA）。记录杂草种类、数量、密度、生物量等指标,并于2016年9月底进行水稻实收测产。结果表明,与CK相比,F0S、F0SA、F1SA和F2SA处理的杂草总密度分别降低50.3%、29.2%、20.3%和6.8%,秸秆还田可以有效降低稻田杂草密度、生物量和杂草多样性;与F0S相比,F0SA、F1SA和F2SA处理的杂草发生数量和发生密度差异不显著,但禾本科和莎草科杂草不同程度地减少,柳叶菜科和玄参科杂草显著增加,配施秸秆腐解剂对农田杂草种类影响显著。在秸秆腐解剂和不同施氮措施下,与F0SA相比,F1SA和F2SA处理杂草种类、生物量增加,杂草相对密度降低,但差异不显著;各处理间优势杂草种类和种群数量减少,但F2SA处理下生物多样性指数明显高于F0SA和F1SA处理。与CK相比,F0S、F0SA、F1SA和F2SA处理的水稻产量分别提高7.13%、16.55%、17.80%和10.67%,其中F1SA处理作物产量增幅最高。研究表明,秸秆还田和氮肥管理能有效降低稻田杂草的发生密度、总生物量和和生物多样性,有利于提高水稻产量。  相似文献   

6.
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.  相似文献   

7.
Development of a target oriented weed control system   总被引：1，自引：0，他引：1  
  相似文献   

8.
Mapping weed cover during the fallow period of dryland crop rotations would be valuable for weed management in subsequent crops and could be done with low cost color digital cameras, however most managers lack the specialized software and expertise needed to create a map from the images. A system of software was developed to quantify weed cover in fallow fields in digital images and to simplify and automate the most challenging tasks that non-GIS professionals confront in creating and using maps derived from a large number of images. A GIS file of image locations is created with inexpensive consumer software. Images are classified, a GIS file is generated and the map is displayed in a simple GIS viewer with free software we developed. A map can be generated from 1000 images and 5000 GPS coordinates in 30 min, including image classification. The classified and original images for all locations can be viewed together easily from the map application. The accuracy of estimating weed cover was evaluated using images collected in 15 fields under natural light with a consumer grade camera mounted on an ATV driving 8-11 km h−1. Weed cover was estimated with 96% accuracy for images, regardless of the amount of crop residue, unless part of the image was shaded by the camera. In those images, accuracy was 90% or better. This system will work with many professional and consumer digital cameras and GPS units and the classification algorithm can be easily modified for other applications.  相似文献   

9.
The non-destructive assessment of forage mass in legume-grass mixtures as a tool for yield mapping in precision farming applications has been investigated in two field experiments. An ultrasonic sensor was used to determine sward heights. Forage mass-height relationships were evaluated by carrying out static measurements on binary legume-grass mixtures of white clover (Trifolium repens L.), red clover (Trifolium pratense L.), and lucerne (Medicago sativa L.) with perennial rye grass (Lolium perenne L.) across a wide range of sward heights (5.0-104.2 cm) and forage mass (0.15-11.25 t ha−1). Mobile measurements, hereafter referred to as “on-the-go” were conducted by mounting the ultrasonic sensor in combination with a high-precision Differential Global Positioning System (DGPS) on a vehicle. Data were recorded along experimental plots consisting of perennial rye grass and grass-clover mixtures similar to the mixtures that were used for the static experiment. The static experiment revealed a relationship between ultrasonic sward height and forage mass explaining 74.8% of the variance with a standard error (SE) of 1.05 t ha−1 in a common dataset. The type of legume species, weed proportion, and growth period had a significant impact on the above mentioned relationship. Legume-specific regression functions had higher R2-values of up to 0.855 (white clover mixture). Datasets including legume-specific mixtures and pure swards of both components reached comparable R2 values between 0.799 and 0.818 but exhibited higher SE values. The abundance of weeds resulted in increased ultrasonic sward heights for the same levels of forage mass. On-the-go measurements across experimental field plots yielded a sward height range of 1.4-70.4 cm. Abrupt forage mass changes at the transition from treatment plots to cut interspaces resulted in a significant deviation from stubble height within a distance of 50 cm to plot borders. When legume-specific equations derived from static measurements were applied to sward heights, forage mass was overestimated by 21.4% on average. Mean residuals from predicted forage mass ranged between 0.893 (pure grass) and 1.672 (red clover mixture) and increased significantly if the point sampling distance along the track was increased to more than 0.82 m on average across all plots. The prediction accuracy of forage mass from ultrasonic height measurements is promising; however, further modifications to the technique are necessary. One such improvement can be the use of spectral reflectance signatures in combination with the ultrasonic sensor.  相似文献   

10.
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.  相似文献   

11.
Pesticide application is an essential practice on many U.S. crop farms. Off-rate pesticide application errors may result from velocity differential across the spray boom while turning, pressure fluctuations across the spray boom, or changes in boom-to-canopy height due to undulating terrain. The sprayer path co-ordinates and the status (on or off) of each boom control section were recorded using the sprayer control console which provided map-based automatic boom section control. These data were collected for ten fields of varying shapes and sizes located in central Kentucky. In order to estimate potential errors resulting from sprayer turning movements, a method was developed to compare the differences in application areas between spray boom control sections. The area covered by the center boom control section was considered the “target rate area” and the difference in these areas and the areas covered by remaining control sections were compared to estimate application rate errors. The results of this analysis conducted with sprayer application files collected from ten fields, many containing impassable grassed waterways, indicated that a substantial portion of the fields (6.5–23.8%) could have received application in error by more than ±10% of the target rate. Off-rate application errors exceeding ±10% of the target rate for the study fields tended to increase as the average turning angles increased. The implication of this is that producers may be unintentionally applying at off-label rates in fields of varying shapes and sizes where turning movements are required.  相似文献   

12.
The current trend in modelling flow phenomena within trees such as in orchards follows the assumption of the space occupied by the trees as a porous and horizontally homogeneous medium to avoid the flow details associated with the individual plants. This being sufficient at a larger field or regional scale much has to be done at a plant scale to analyse the flow details within the plant and its elements especially for sensitive agricultural operations such as spraying. This article presents an integrated 3D computational fluid dynamics (CFD) model of airflow from a two-fan air-assisted cross-flow orchard sprayer through non-leafed orchard pear trees of 3 m average height. In this model the effect of the solid part of the canopy on airflow was modelled by directly introducing the actual 3D architecture of the canopy into the CFD model. The effect of small canopy parts, such as very short and thin branches and flowers that were not incorporated in the geometrical model, on airflow was simulated by introducing source-sink terms in the Reynolds averaged Navier-Stokes (RANS) momentum and k-? turbulence equations in a sub-domain created around the branches. This model was implemented in a CFD code of ANSYS-CFX-11.0 (ANSYS, Inc., Canonsburg, PA, USA). In this work it was possible to link the real 3D architecture of pear canopy into a CFD code of CFX. The model was able to capture the local effects of the canopy and its parts on wind and sprayer airflow directly by inserting the tree structure into the model which gave realistic results. The model showed that within the injection region of the sprayer there was an average reduction of the jet velocity by 1 m s−1 for a distance of 2.3 m from the sprayer outlet due to the presence of leafless pear canopy. This reduction was variable at different vertical positions due to the difference in the canopy density. Maximal effect of the canopy was observed in the middle height of the trees between 0.25 m and 2.5 m which is the denser region with a bunch of several branches. The maximum velocity difference observed between these two positions was 1.35 m s−1 at 1.75 m height. Thus, regions of high and low air velocity zones of the sprayer due to the variable branch density of the pear tree were predicted. The effects of wind speed and direction on the air jet from the sprayer were investigated using the model. For a cross- (direction of 90°) wind speed of 5 m s−1 there was about 2 m s−1 reduction in the sprayer jet velocity at the jet centre and 0.5 m horizontal shift of the jet centre towards the wind direction. Generally there was a decrease in the jet velocity with increasing cross-wind and decreasing wind direction with respect to the jet direction.  相似文献   

13.
Evaluation of ultrasonic sensor for variable-rate spray applications   总被引：2，自引：0，他引：2  
Automatic variable-rate sprayers require accurate measurement of canopy size. An estimate of canopy size is made by measuring the distance to the canopy at several elevations above the ground; an ultrasonic sensor was used to determine canopy distance in this study. It is sometimes necessary to conduct spray operations during harsh operating conditions. In this study ultrasonic sensors were subjected to simulated environmental and operating conditions to determine their durability and accuracy. Conditions tested included exposure to extended cold, outdoor temperatures, cross winds, temperature change, dust clouds, travel speeds and spray cloud effects. The root mean square (RMS) error in a series of measurements of the distance to a simulated plant canopy was used to test for significant difference among treatments. After exposure to outdoor cold conditions for 4 months, the RMS error in distance measured by the ultrasonic sensor increased from 3.31 to 3.55 cm, which was not statistically significant. Neither the presence of dust cloud nor the changes in cross-wind speeds over a range from 1.5-7.5 m/s had significant effects on the mean RMS errors. Varying sensor travel speed from 0.8 to 3.0 m/s had no significant influence on sensor detection distances. Increasing ambient temperature from 16.7 to 41.6 °C reduced the detection distance by 5.0 cm. The physical location of the spray nozzle with respect to the ultrasonic sensor had a significant effect on mean RMS errors. The mean RMS errors of sensor distance measurements ranged from 2.3 to 83.0 cm. The RMS errors could be reduced to acceptable values by proper controlling the sensor/spray nozzles spacing on a sprayer. In addition, multiple-synchronized sensors were tested for their measurement stability and accuracy (due to possible cross-talk errors) when mounted on a prototype sprayer. It was found that isolating the pathway of the ultrasonic wave of each sensor reduced detecting interference between sensors during multiple sensor operation. Test methods presented herein may be useful in the design of standardized testing protocols for field use distance sensors.  相似文献   

14.
Automatic section control (ASC) has been readily adopted by US producers on sprayers because it can improve operator productivity and decrease overlap or input usage leading to economic savings while reducing environmental impacts. However, there is limited knowledge about nozzle flow dynamics when shutting ON/OFF of boom-sections or nozzles and the possible impact on application accuracy. Therefore, an investigation was conducted to evaluate system response in managing real-time nozzle off-rate and flow uniformity across the boom, for a typical agricultural sprayer using ASC. An 18.3-m sprayer was outfitted with commercially available individual nozzle and boom-section control. Tests were conducted to simulate sprayer moving out of point rows into a no-spray zone and then reentry into the spray zone by selecting two point row scenarios having 20° and 70° angles. Ten high frequency response pressure sensors were randomly mounted across the boom to measure nozzle pressure. The nozzle pressures were converted to nozzle flow, using the manufacturers pressure versus flow relationship, to calculate nozzle flow rate delay time, settling time, percent off-rate (percent difference between actual and target nozzle flow rate) and nozzle flow uniformity (CV), considering only ON boom-sections. Auto-boom scenarios were conducted with and with-out flow compensation while auto-nozzle scenarios were conducted without flow compensation. Results indicated that nozzle flow rate settling time varied from 0.4 to 14.4 s and nozzle off-rate between 36.6% and +28.7% for 70° point row auto-boom tests when exiting and reentering point rows. When exiting point rows, over-application occurred whereas reentry resulted in under-application during flow compensated tests. Nozzle flow uniformity (CV) were more than 50% for a short duration (<1.0 s) when reentering point rows, during all tests. Compensation testing for 20° point row reentry highlighted the constraint of the control system to respond to certain situations where feedback response times could not match target rates rapidly set for the controller. Overall results indicated that system response time can impact nozzle off-rate and can vary with point row angle.  相似文献   

15.
采用单因素随机区组设计,通过种子萌发试验,对贵州省黔南长顺、贵定烟区烟田土壤杂草种子库的组成、数量及杂草种子萌发的规律进行了研究。结果表明,该区土壤杂草种子库共有杂草种类13科18种,主要分布在0~10 cm土层,约为该区土壤杂草生长总量的54.41%。杂草种类主要有禾本科看麦娘(Alopecurus aequalis Sohcl)、金色狗尾草(Setaria gleuca(linn.)beauv),占该区烟田土壤杂草数量的70.48%,是该区杂草防治的重点;其中,长顺烟田土壤杂草种子较多,0~30 cm土层的杂草种子密度为24 180粒/m2,贵定烟田相对较少,为14 660粒/m2。  相似文献   

16.
[目的]为明确不同耕作模式对玉米田土壤杂草种子库的影响,研究翻耕和免耕模式下玉米田杂草种子库的组成和特征。[方法]采用杂草种子萌发法,将0~5、5~10、10~15、15~20、20~25、25~30 cm 6个不同土层的土壤样本分别装盆,在自然条件下生长60 d后调查杂草种类和数量,计算种子库的密度和相对优势度。[结果]翻耕玉米田共有杂草15科24种,免耕玉米田有15科23种,其中19种杂草在翻耕和免耕玉米田均有分布,主要优势杂草为稗草、藜、铁苋菜、龙葵和马唐,杂草类型上以阔叶杂草为主,禾本科杂草较少。翻耕玉米田杂草种子库总密度为4 292.4粒/m2,主要分布在0~5、20~25、25~30 cm土层,其中稗草的密度和相对优势度最高;免耕玉米田总密度为3 337.0粒/m2,主要分布在15~20、20~25 cm土层,其中藜的密度和相对优势度最高。不同耕作模式的优势杂草在土层中的分布有较大差别,稗草在翻耕田主要分布于25~30 cm土层,而在免耕田主要分布于0~5 cm土层;藜在免耕田主要分布于20~25cm土层,而在翻耕田各土层呈较均匀分布。[结论]明确了不同耕作模式土壤杂草种子库的组成和特征,为农田杂草的综合管理提供理论依据。  相似文献   

17.
[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。  相似文献   

18.
In sugar beet, maize and soybean, weeds are usually controlled by herbicides uniformly applied across the whole field. Due to restrictions in herbicide use and negative side effects, mechanical weeding plays a major role in integrated weed management (IWM). In 2015 and 2016, eight field experiments were conducted to test the efficacy of an OEM Claas 3-D stereo camera® in combination with an Einböck Row-Guard® hoe for controlling weeds. Ducks-foot blades in the inter-row were combined with four different mechanical intra-row weeding elements in sugar beet, maize and soybean and a band sprayer in sugar beet. Average weed densities in the untreated control plots were from 12 to 153 plants m?2 with Chenopodium album, Polygonum convolvulus, Thlapsi arvense being the most abundant weed species. Camera steered hoeing resulted in 78% weed control efficacy compared to 65% using machine hoeing with manual guidance. Mechanical intra-row elements controlled up to 79% of the weeds in the crop rows. Those elements did not cause significant crop damage except for the treatment with a rotary harrow in maize in 2016. Weed control efficacy was highest in the herbicide treatments with almost 100% followed by herbicide band-applications combined with inter-row hoeing. Mechanical weed control treatments increased white sugar yield by 39%, maize biomass yield by 43% and soybean grain yield by 58% compared to the untreated control in both years. However, yield increase was again higher with chemical weed control. In conclusion, camera guided weed hoeing has improved efficacy and selectivity of mechanical weed control in sugar beet, maize and soybean.  相似文献   

19.
覆膜种植对甘南高寒区苜蓿生长和杂草数量的影响   总被引：1，自引：0，他引：1  
【目的】甘南高寒区缺乏适宜的苜蓿栽培和苜蓿草地杂草防除技术,严重影响了该区域苜蓿和草地畜牧业的发展。研究不同覆膜种植方式对甘南高寒区种植当年苜蓿和杂草生长的影响,为建立优质苜蓿草地提供依据。【方法】在甘肃省夏河高寒草地,比较垄沟覆膜、平膜、垄沟和普通种植方式对苜蓿和杂草生长的影响。【结果】普通种植和垄沟种植下的苜蓿株高分别为14.4和19.1 cm,显著低于垄沟覆膜和平膜种植（P＜0.05）。垄沟覆膜下的苜蓿一级分枝数为7.7个,显著高于平膜（5.2个）、垄沟（4.8个）和普通种植（4.5个,P＜0.05）。垄沟覆膜和平膜种植的苜蓿主茎粗分别为2.70 mm和2.50 mm,两者间无显著差异（P＞0.05）,但均显著高于垄沟和普通种植（P＜0.05）。垄沟覆膜下的苜蓿根颈粗为6.19 mm,显著高于平膜种植（5.29 mm）（P＜0.05）;平膜种植下的苜蓿根颈粗显著高于垄沟种植（3.99 mm）,垄沟种植下的苜蓿根颈粗显著高于普通种植（2.80 mm）（P＜0.05）。垄沟覆膜种植下的苜蓿根颈入土深度为2.73 cm,显著高于平膜种植（2.24 cm）（P＜0.05）。与普通种植和垄沟种植相比,垄沟覆膜种植苜蓿根颈入土深度分别提高了56.0%和29.4%。垄沟覆膜种植下的苜蓿干草产量为1 503.2 kg·hm-2,显著高于平膜种植（1 089.6 kg·hm-2）、垄沟种植（317.6 kg·hm-2）和普通种植（224.4 kg·hm-2）（P＜0.05）。高寒区垄沟覆膜和平膜种植下0-10、10-20、20-30、30-40和0-40 cm土层的苜蓿根体积、根表面积和根生物量均显著高于垄沟种植和普通种植（P＜0.05）;除30-40 cm土层外,垄沟种植均显著高于普通种植（P＜0.05）。供试苜蓿人工草地种植的第一年,共发现21种杂草,主要以香薷、乳浆大戟、节裂角茴香和藜等一年生杂草为主。垄沟和普通种植下的杂草物种数最多,分别为14.3和13.3种,二者间无显著差异（P＞0.05）;但均显著高于平膜（9.7种）和垄沟覆膜种植（9.3种）;后二者间也无显著差异（P＞0.05）。杂草总密度最高的是垄沟种植,为272.3株/m2,高于普通种植（241.7株/m2）;二者显著高于平膜（74.0株/m2）和垄沟覆膜种植（86.0株/m2）（P＜0.05）。杂草地上部分生物量干重最高的是垄沟覆膜种植,为186.8 g·m-2;其次为平膜处理（157.7 g·m-2）、垄沟（88.5 g·m-2）和普通种植（79.0 g·m-2）。【结论】利用黑色地膜进行的垄沟覆膜和平膜处理提高了甘南高寒区苜蓿种植当年的株高、主茎粗、根颈粗、根颈入土深度和干草产量,显著提高了苜蓿的根系生物量、根表面积和根体积,提高了优势杂草的生物量和株高,极大降低了杂草物种类和密度。  相似文献   

20.
A computational fluid dynamics (CFD) model to simulate airflow from air-assisted orchard sprayers through pear canopies was validated for three different sprayers; single-fan (Condor V), two-fan (Duoprop) and four-fan sprayers (AirJet Quatt). The first two sprayers are widely used in Belgium and the latter one is a new design. Validation experiments were carried out in an experimental orchard (pcfruit, Velm, Belgium) in spring 2008. Ultrasonic anemometers were used to measure the time-averaged velocity components at different vertical positions before the tree and after the tree when the sprayers were driven through the orchard. The model was able to predict accurately the peak jet velocity, Um from all the sprayers considered at all distances from the sprayer centre and vertical positions. More than 95% of the local relative errors of Um were below 20%. Average relative errors, E, and root mean square errors, ERMS, were all less than 11.04% and 1.68 m s−1, respectively. The regions of high- (up to 18.0 m s−1 upstream) and low (down to 2.8 m s−1 downstream)-air velocity zones for all the sprayers were accurately predicted. The simulation results showed that the Condor V sprayer had a highly disturbed vertical jet velocity profile, especially at higher heights. The Duoprop sprayer had high jet velocities at the two-fan positions and lower jet velocity in between the two fans. Within the canopy height the AirJet Quatt sprayer showed a more uniform distribution of air than the other two sprayers except the minor peaks at the fan positions. These situations were all confirmed by the measurements.  相似文献   

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