Assessing GNSS correction signals for assisted guidance systems in agricultural vehicles

Accuracy levels achieved with differential global positioning system (DGPS) receivers in agricultural operations depend upon the quality of the correction signal. This study has assessed differential signal error from a Dedicated Base Station, OmniSTAR VBS, European Geostationary Navigation Overlay System, European reference frame-IP for internet protocol (EUREF-IP) and radio navigation satellite aided technique (RASANT). These signals were utilized in guidance assisting systems for agricultural applications, such as tillage, harvesting, planting and spraying, in which GPS receivers were used under dynamic conditions. Simulations of agricultural operations on different days and at different time slots and simultaneously recording the tractor′s geo-position from a DGPS receiver and the tractor′s geo-position from a real-time kinematic (RTK) GPS allowed the comparison of the GPS correction signals. The hardware used for tractor guidance was a lightbar (Trimble model EZ-Guide Plus) system. ANOVA statistics showed a significant difference between the accuracy of the correction signals from different sources. GPS correction signal recommendations to farmers depend upon the accuracy required for the specific operation: (a) Yield monitoring and soil sampling (<1 m) are possible with all the GPS correction signals accessed in any time slot. (b) Broadcast seeding, fertilizer and herbicide application (<0.5 m) are possible for 80% of time with OmniSTAR VBS, 40% of time with RASANT and EUREF-IP and 100% of time with a dedicated base station. (c) Transplanting and drill seeding (<0.04 m) are not possible with the accuracy correction provided by any one of the systems used in this study.     

Propagation of positional measurement errors to agricultural field boundaries and associated costs

It has been argued that the upcoming targeted approach to managing field operations, or precision farming, requires that field boundaries are measured with cm level accuracy, thus avoiding losses such as wasted inputs, unharvested crops and inefficient use of the land. This paper demonstrates a method for verification of such claims, based on a statistical model that accounts for temporal correlation in positional measurement errors. Our implementation employs the Data Uncertainty Engine (DUE), which is free software that aids the user in defining probability distributions for uncertain spatial objects, and draws random samples from these distributions. A case study concerning the financial consequences of uncertain geometry for a farmer who uses a digital map to optimise field operations for 15 ha of a potato crop is presented. The error model was parameterised on measurement scenarios representing (1) the Dutch registry of agricultural fields; (2) differential GPS-based field checks for verification of area declarations; and (3) special purpose Real Time Kinematic (RTK)-GPS surveys. We found that a farmer who has a manually digitised map of the study area would benefit from a RTK-GPS survey in a single crop year if the survey would cost less than € 442. An independent test case showed that the results of the error model were consistent with field data.     

双行打塘机械的自动计数装置研发与应用

针对烟草种植中小苗膜下移栽的打塘开穴需求,研制了双行打塘机械及配套的自动计数装置,该双行打塘机械由拖拉机悬挂牵引作业时,由地轮驱动作业铁铲交替上下周期运动进行双行打塘作业,以单片机为核心的自动计数装置可以实现打塘开穴作业数目的自动计数。田间试验表明,双行打塘机械可达到烟苗移栽所需的开穴作业要求,自动计数装置可精确自动计数打塘开穴数目。     

石城县多功能烟草作物打穴施肥机的应用推广试验研究

[目的]研究多功能烟草作物打穴施肥机的应用效果与推广价值。[方法]对多功能烟草作物打穴施肥机(T)与人工作业(CK)在不同土壤类型、不同垄型作业用工、作业质量与作业成本进行对比分析。[结果]多功能烟草作物打穴施肥机能大大降低烟农打穴施肥环节劳动强度和用工成本,且穴深、穴宽、株距均匀,施肥量精准,土肥混合均匀细碎,大大提高了打穴施肥工作效率,平均降低作业成本1 681.93元/hm~2。[结论]多功能烟草作物打穴施肥机作业效率远高于人工作业,有较高的推广使用价值。     

Procedures of soil farming allowing reduction of compaction

Evaluation of new technologies using guidance systems is very important and can help producers with choosing the right equipment for their applications. Without using satellite navigation during field operations, there is a tendency for passes to overlap. That results in waste of fuel and pesticides, longer working times and also environmental damage. When utilising satellite guidance for field operations, there is a close connection with controlled traffic farming (CTF) as well. CTF is currently a quite quickly developing farming system based on fixed layout of machinery passes across a field. Tracks precisely set out for a machine’s tyres in the field could be a tool for minimising soil compaction risk which is another threat to the environment. The purpose of this paper was to evaluate the accuracy of currently available guidance systems for agricultural machines. Real pass-to-pass errors (omissions and overlaps) in a field were measured. Consequently, comparison between observed guidance systems was made regarding final working accuracy. Further, intensity of machinery passes, percentage of wheeled area and repeated passes in fields were monitored. These measurements were made in fields under real operating conditions using a conventional tillage system with ploughing and also a conservation tillage system, both systems with randomly organized traffic. Finally, the same parameters were monitored in fields where fixed machinery tracks were used for all operations and passes but only under a conservation tillage system. Pass-to-pass accuracy was measured for the evaluation of different guidance systems. Size of missed areas or overlaps was evaluated statistically. Concerning intensity of machinery passes and total field area affected by machinery passes, the following facts were found out. The experiments with randomized traffic showed a significant difference of the parameters mentioned above between a conventional tillage system with ploughing and a conservation tillage system. Wheeled area was 86 and 64%, respectively which proves benefits of conservation tillage. The experiments with a fixed track system showed that the total run-over area by machinery tyres decreased even more (up to 31%) in comparison to randomized traffic in a field (only fields under conservation tillage system were monitored and evaluated). The following statements based on our results can be made. The navigation and therefore possibility for better accuracy of machinery passes in fields together with permanent machinery tracks utilization could help with soil condition improvement and also energy savings which would result from that. The CTF system will help with further development of a system for soil compaction protection which is currently a real necessity.     

SPC技术在烟叶打叶复烤质量管理中的应用

为提高烟叶打叶复烤质量控制精度,尝试应用SPC（统计过程控制）技术从整个过程来评价、提高打叶复烤过程的加工能力。通过运用SPC技术的统计方法、控制图,提高过程能力水平,实现从结果控制向过程控制、从人工控制向自动控制的转变,起到稳定提高片烟产品质量的作用。     

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.     

A loss function to evaluate agricultural decision-making under uncertainty: a case study of soil spectroscopy

Modern sensor technologies can provide detailed information about soil variation which allows for more precise application of fertiliser to minimise environmental harm imposed by agriculture. However, growers should lose neither income nor yield from associated uncertainties of predicted nutrient concentrations and thus one must acknowledge and account for uncertainties. A framework is presented that accounts for the uncertainty and determines the cost–benefit of data on available phosphorus (P) and potassium (K) in the soil determined from sensors. For four fields, the uncertainty associated with variation in soil P and K predicted from sensors was determined. Using published fertiliser dose–yield response curves for a horticultural crop the effect of estimation errors from sensor data on expected financial losses was quantified. The expected losses from optimal precise application were compared with the losses expected from uniform fertiliser application (equivalent to little or no knowledge on soil variation). The asymmetry of the loss function meant that underestimation of P and K generally led to greater losses than the losses from overestimation. This study shows that substantial financial gains can be obtained from sensor-based precise application of P and K fertiliser, with savings of up to £121 ha^?1 for P and up to £81 ha^?1 for K, with concurrent environmental benefits due to a reduction of 4–17 kg ha^?1 applied P fertiliser when compared with uniform application.

     

Automatic delineation algorithm for site-specific management zones based on satellite remote sensing data

In light of the increasing demand for food production, climate change challenges for agriculture, and economic pressure, precision farming is an ever-growing market. The development and distribution of remote sensing applications is also growing. The availability of extensive spatial and temporal data—enhanced by satellite remote sensing and open-source policies—provides an attractive opportunity to collect, analyze and use agricultural data at the farm scale and beyond. The division of individual fields into zones of differing yield potential (management zones (MZ)) is the basis of most offline and map-overlay precision farming applications. In the process of delineation, manual labor is often required for the acquisition of suitable images and additional information on crop type. The authors therefore developed an automatic segmentation algorithm using multi-spectral satellite data, which is able to map stable crop growing patterns, reflecting areas of relative yield expectations within a field. The algorithm, using RapidEye data, is a quick and probably low-cost opportunity to divide agricultural fields into MZ, especially when yield data is insufficient or non-existent. With the increasing availability of satellite images, this method can address numerous users in agriculture and lower the threshold of implementing precision farming practices by providing a preliminary spatial field assessment.     

Implement lateral position accuracy under RTK-GPS tractor guidance

The accuracy of global positioning system receivers can be improved by differential correction systems (DGPS), which deliver sub-meter accuracy. Higher-accuracy, of about 1 cm on-the-go, is delivered by units generally referred to as real-time kinematic (RTK) DGPS systems. RTK-DGPS systems are presently used by commercial companies for automatic guidance of tractors in row-crop operations. Since high-end DGPS systems with high-accuracy are generally very expensive, it is necessary that the commercial benefit be maximized and that any related errors will be minimized. In the present study, the deviations from a predetermined route of a three-point hitch implement mounted on a RTK-DGPS based automatically guided tractor were recorded and were used to validate that the implement deviation is strongly dependent on the distance from the tractor rear axle. The recorded deviations were analyzed for paved and rough surfaces; the latter caused substantially greater deviations. Based on the above hypothesis, a possible way to improve the performance by reducing the deviations at a point on the implement is suggested.     

国内气力式玉米精量排种器研究进展

近年来，我国机械化技术水平不断提高，精量播种正逐步取代传统的粗放式播种，从而降低了种植成本，同时提高了生产效率和利润。目前，我国玉米单产水平存在较大提升空间，提升玉米机械播种水平是提高玉米播种质量和增加产量的有效方式。本文对气力式玉米精量排种器的研究现状进行了综述，包括气吸式、气吹式和气压式3种类型，分别总结了其结构、工作原理和工作参数、性能、优势等，评述了试验效果；针对玉米精量排种器目前存在的问题进行了分析，并提出了未来的发展趋势，以期为促进玉米机械化生产提供参考。     

Regional model for nitrogen fertilization of site-specific rainfed corn in haplustolls of the central Pampas,Argentina

In semi-arid regions, soil water and nitrogen (N) are generally limiting factors for corn (Zea mays L.) production; hence, implementation of appropriate N fertilization strategies is needed. The use of precision agriculture practices based on specific site and crop properties may contribute to a better allocation of fertilizer among management zones (MZ). The aim of this study was to develop a model for diagnosis of N availability and recommendation of N fertilizer rates adjusted to MZ for dryland corn crops growing in Haplustolls. The model considered variability between MZ by including site-specific variables [soil available water content at sowing (SAW) and Available Nitrogen (soil available N-NO₃ at planting + applied N, Nd)] using spatial statistical analysis. The study was conducted in Córdoba, Argentina in Haplustolls and consisted in four field trials of N fertilizer (range 0–161 kg N ha⁻¹) in each MZ. The MZ were selected based on elevation maps analysis. Grain yields varied between MZ and increased with larger SAW and Nd at sowing. Grain responses to Nd and SAW in any MZ were not different between sites, allowing to fit a regional model whose parameters (Nd, Nd², SAW, SAW²) contributed significantly (p < 0.001) to yield prediction. Agronomical and economically optimum N rates varied among MZs. However, the spatial variability of optimum N rates among MZs within sites was not enough to recommend variable N fertilizer rates instead of a uniform rate. Variable N fertilizer rates should be recommended only if variability in SAW and soil N among MZ is greater than that found in this work.     

云南三七工厂化育苗工程技术体系分析

结合三七的生长特性,从系统工程视角分析了三七工厂化育苗的基本工艺流程;将三七工厂化育苗周期划分为播种前期准备、播种期实施和播种后期管理三个阶段,分析了各阶段相关设施设备的现状,指出设备选型过程中出现的问题。提出研发适宜三七的精密播种机,针对三七育苗不同生长阶段对自动控制设备进行改进,研发三七大田移载与精准施肥相关设备,研发三七机械化收获与烘干工程等设备的建议。     

Combine Harvester Control Using Real Time Kinematic GPS

An accurate vehicle guidance system is required for some precision agriculture operations. It can be used for high speed direct seeding on a farm tractor. Such a system also ensures neither overlapping nor missing areas during the harvest, even when visibility is poor. But, automatic path following in the field is a difficult problem. Many vehicle guidance systems have been studied. Some use two dimensional (2D) information, while others are based upon 3D information. Most of the sensors use output information relative to their environment without absolute reference of the path. As the new reference is based on the previous pass, one of the main problems encountered with the edge following systems is an increase in the amplitude of oscillations due to guidance errors in successive passes. Thus, human operators frequently and periodically sacrifice efficiency in one pass to straighten out the edge of the worked area. Another kind of sensor, centimeter accuracy Real-Time Kinematic based Global Positioning System (GPS) receivers, can be used. The advent of accurate systems, with a standard deviation from the mean of about 10 mm, allows the design and implementation of absolute vehicle guidance systems. A few approaches to GPS-based control systems also include attitude measurement sensors such as fiber optic gyroscope. The preliminary work presented in this paper was aimed at validating the use of a GPS receiver in a vehicle guidance system, without any orientation sensor. We have designed a controller to perform a line-following task. Real-time experiments have been carried out on a combine harvester.     

A meta-analysis of factors driving the adoption of precision agriculture

Using a literature pool spanning 23 years, this meta-analysis quantifies the effect of factors underlying the adoption of precision agriculture. Unlike statistical significance, which demonstrates how likely adoption is due to chance, effect size indicates the importance of a factor to adoption. This meta-analysis finds that perceived profitability, consultants and use of a computer factors have a moderate effect. However, the findings should not be regarded as definitive because of issues of sample size and heterogeneity embedded in a number of the reference studies. This latter point is re-enforced by observation of other factors that had a negligible effect on adoption. Whether future studies will provide meaningful policy implications depend on a careful understanding and selection of factors, models, and statistical treatment in relation to decision-making paths and their context.

     

Automatic blood sampling in dairy cows

Loose housing systems for dairy cows are becoming increasingly common, raising new questions in the area of animal health and welfare. Some of these questions can be addressed by studying the variation in blood parameters, such as glucocortistioids. However, the traditional manual blood sampling procedure can in itself affect the responses of the animal. To address this issue we have developed a device for automated collection of multiple blood samples. The device is placed on the back of the animal and allows the animal to be kept in all types of environments, either alone or in social groups. The animal can move freely: no restraints and no handling of the animal are necessary during blood sampling.Three experiments were conducted to study the performance of the system and how the blood sampling procedure affected the cortisol responses in dairy cows. In the first experiment the accuracy of sample size and timing were investigated.In the second experiment, automatic samples were collected from six cows kept in tie-stalls, with samples taken at 3-min intervals for 38 min. At 12, 24, 36 and 38 min, a manual sample was taken by vein puncture. None of the cows showed a consistently increased cortisol response to automatic sampling, while two cows showed increased cortisol concentration after vein puncture.In the third experiment automatic blood sampling was conducted with 12 cows kept in a loose housing system. In the morning, over a period of 1.5 h, 14 blood samples were taken at varying time intervals from each cow. In the afternoon, over a period of 2.5 h, a further 14 samples were taken. Cortisol concentrations in the blood samples suggest that the cows were not affected by the blood sampling procedure.On some occasions during these experiments, it was not possible to get a sample. For the manual vein puncture 3 out of 24 samples (12.5%) were not successfully taken within a time limit of 2 min. During the automatic blood sampling process, the catheter occasionally became twisted and blocked by the movement of the cow's head. This occurred in 8 out of 84 samples (9.5%). In four of the manual samples, considerable hemolysis had occurred during the sampling procedure. No hemolysis was observed in the automatic blood samples.Automated blood sampling offers the opportunity to collect a series of samples without disturbing the animal. Data suggest that automatic blood sampling is a superior alternative to manual blood sampling, even in a tie barn.     

Near-infrared spectroscopic sensing system for on-line milk quality assessment in a milking robot

A near-infrared (NIR) spectroscopic sensing system was constructed on an experimental basis. This system enabled NIR spectra of raw milk to be obtained in an automatic milking system (milking robot system) over a wavelength range of 600–1050 nm. Calibration models for determining three major milk constituents (fat, protein and lactose), somatic cell count (SCC) and milk urea nitrogen (MUN) of unhomogenized milk were developed, and the precision and accuracy of the models were validated. The coefficient of determination (r²) and standard error of prediction (SEP) of the validation set for fat were 0.95 and 0.25%, respectively. The values of r² and SEP for lactose were 0.83 and 0.26%, those for protein were 0.72 and 0.15%, those for SCC were 0.68 and 0.28 log SCC/mL, and those for MUN were 0.53 and 1.50 mg/dL, respectively. These results indicate that the NIR spectroscopic system can be used to assess milk quality in real-time in an automatic milking system. The system can provide dairy farmers with information on milk quality and physiological condition of an individual cow and, therefore, give them feedback control for optimizing dairy farm management. By using the system, dairy farmers will be able to produce high-quality milk and precision dairy farming will be realized.     

烟草漂浮育苗单粒播种技术验证及应用

为验证烟草漂浮育苗单粒播种的可行性,选用烤烟‘云烟87’催芽包衣种,设计试验方案T1压穴、播种、盖种一体化手工播种器;T2为压穴、播种、盖种分离式手工播种器;CK为自动播种机。手工播种器播种时1 穴仅播种1 粒,播种机播种时周边行播2 粒,其余孔穴播1 粒。实验数据采用随机取样的方式,统计各处理的出苗率、双苗率、多苗率以及大十字期间苗、补苗用工量和用工成本等进行对比分析。结果显示,播种机播种的出苗率仅为85.9%,双苗率和多苗率分别达到32.4%、13.4%,且每盘增加了间苗、补苗费0.8 元。播种器单粒播种的出苗率均在90%以上,在气温较低的1 月也达91.7%,每盘可节约间苗补苗费0.8 元。集压穴、播种、盖种一体化的手工播种器不但提升了出苗率、整齐度和烟苗素质,而且还降低了生产成本和传毒风险,节约了生产用种。     

印刷播种技术对机插秧苗素质和栽插质量的影响

以常规粳稻连粳9号为供试品种,使用印刷播种技术分别印刷0.8cm×0.8cm、0.7cm×0.7cm、0.7cm×0.6cm、0.6cm×0.6cm的附种纸,考察其种子分布情况,并为其设置同等播种量的手工播种方式,在同等条件下进行大田育苗和栽插比较。结果表明：1）印刷播种附种纸空缺率低于1.0%,双种率17%左右,种子分布均匀一致;2）4个印刷播种处理所育秧苗素质均高于手工播种对照;3）大田每穴栽插苗数均匀一致,栽插质量显著高于对照。     

基于小区育种路径自对齐的小麦小区播种机改进

育种专家在进行小麦小区育种时,需要精准地对播种区域进行划分。但传统小麦小区播种机在播种过程中,各小区各行无法精准对齐,导致育种区域混乱,影响育种效果。为了解决小麦小区播种路径精准对齐的问题,本文在长期实验的基础上,将北斗卫星定位与小麦小区育种相结合。首先,获取播种机经纬度,通过建立相对坐标系,构建播种机的小区路径模型,得到规划的路径,取代了传统人工画线的过程。使用本文提出的方法进行小麦小区播种,在5 cm的误差范围内,播种准确度提高了32%。同时,考虑到农田作业环境复杂和人工驾驶的能力有限,北斗卫星定位本身也存在厘米级的误差,为了进一步提高小区路径规划的精准度,本文提出了一种算数平均值滤波与卡尔曼滤波相融合的算法,在相对坐标系下,对基准路径的斜率值进行迭代递推处理。经实验,使用算数平均值滤波与卡尔曼滤波相融合的算法,能有效地对实际计算的斜率值进行修正,最小的修正幅度为20.1%,最大的修正幅度达到4 871.4%。本文研究结果可为北斗卫星定位在小区播种机路径精准规划提供参考。