Spatial aspects of weed control

Interaction between weed control and weed spread is discussed. A computer simulation model is used to examine four practical control strategies, each differing in spatial and temporal aspects. The efficiency of the four strategies is assessed in economic terms, for three rates of weed spread. The four strategies were shown to differ in their costs. The differences became more marked as the rate of weed spread increased. Moreover, the ranking of the control strategies, in terms of relative cost, changed as the rate of weed spread changed.The model highlights the importance of weed spread to decision-making in weed control programmes and provides some policy guidelines. It also provides a framework for specific case studies.     

Optimal management of molds in stored corn

Long term storage of corn is becoming more common due to the recent increase in the demand for corn by ethanol plants. Infection of maize kernels by toxigenic fungi remains a challenging storage problem despite decades of research. Experts in storage management propose the use of a combination of preventive and monitoring-based responsive strategies in response to mold risks. In this paper, a stochastic dynamic programming model is solved to determine the expected profitability and optimal combination, timing, and intensity of the proposed mold management strategies using farmers’ existing infrastructure. The results show that even with relatively high monitoring costs, maintaining high quality grain using a monitoring-based optimal mold management strategy costs less than the benefit it fetches. The current typical practice by Indiana farmers of aerating the grain until the end of December and doing nothing thereafter bears a high risk of economic losses if grain is to be stored until later during the summer. Generally, the optimal mold management strategy depends on monitoring the biophysical conditions of the grain and the time period under consideration. If the in-bin temperature is high and less than 5% of kernels are mold damaged, then aerating when the outside temperature is at least 3 °C less than the in-bin temperature and continuing to store the grain is the optimal strategy.     

甜菜联合收获机输送升运装置设计

甜菜收获季节性强,劳动强度大,作业效率低,甜菜联合收获机能减轻劳动强度、提高作业效率,是甜菜机械化生产机具的发展趋势。设计了甜菜联合收获机输送升运装置,解决了甜菜收获作业的关键技术,有效降低了甜菜含杂率和粘土率,对甜菜收获机的发展起到巨大的推动作用。      

金融风险管理的新阶段——全面风险管理

金融风险管理是一项复杂并且技术性很强的工作。为了有效地管理各种金融风险，人们必须借助各种专门的管理工具，运用各种专门的管理策略。全面风险管理是一个将企业风险管理融入到企业战略、组织结构、业务流程等各个环节的过程，它需要全员的参与。为了让全员参与到全面风险管理中去，除了通过制度、绩效考核等手段外，更重要的是应该在商业银行内部形成全面风险管理的企业文化和意识。     

A study of the effect of the interaction between site-specific conditions, residue cover and weed control on water storage during fallow

In the semiarid central region of Argentina the probability that rainfall meets crop requirements during growing season is less than 10%, therefore fallowing has been the most important practice to assure water availability during the growing season. Various site-specific and management factors have been identified as crucial for defining fallow efficiency (FE) and final available water contents (AW). The objective of the present study was to improve our knowledge about the interactions between residue cover, weed control, soil profile depth and water storage capacity (WSC) on FE. In 10 sites covering the environments of calcareous plains and sandy plains of the semiarid central region of Argentina and with different WSC, experiments with 3 different levels of residue cover (H, M, L) and with and without weed control (C and W respectively) during fallow were set up. A completely randomized block design with four repetitions and splits plots to consider weed control was used. Soil texture and organic matter were determined in samples of the A horizon (0.20 m). Bulk density, field capacity, permanent wilting point and soil water contents (monthly frequency) were measured at depth intervals of 0.20 m to the depth of the calcite layer or to 2.00 m depth. Soil temperature was taken in weekly intervals at 0.05 m depth and weed plants, separated by species, were counted at the end of fallow in 4 repetitions of 0.25 m² in each treatment. An empirical model was developed to predict final AW under these experimental conditions. Model parameters were: Residue level, weed control, WSC, profile depth, and rainfall during fallow. Site-specific conditions (WSC and profile depth) affected water storage during fallow; soils with highest values for both parameters showed highest final AW. Weed density was the most important factor that controlled AW, with on average 35 mm less AW in W than in C treatments. Residue level had a positive effect on final AW in both C and W treatments, with a difference of 18.5 mm between H and L. An interaction between residue level and weed density was observed, indicating weed suppression in H treatments. This was also confirmed by correspondence analysis between residue level and weed species which revealed that different species were related to each level. High residue levels also decreased soil temperature, thus affecting germination of post-fallow crops. The empirical model had an overall average prediction error of 13.7% and the regression between measured and predicted values showed a determination coefficient of 0.77.     

杂草信息实时获取技术与设备研究进展

杂草信息的实时获取技术是田间杂草精准控制研究的首要问题,杂草实时获取设备是制约精准除草作业实现的瓶颈.综述了基于光谱、图像和光谱成像技术的杂草实时获取技术与设备的国内外研究现状,以促进精准杂草管理技术在我国的应用和发展.基于光谱的杂草信息获取方法较适用于实时防除作物出苗前的杂草,国外已有WeedSeeker、Weed-IT等杂草传感器.基于图像的杂草信息获取方法较适用于识别行间杂草,国外已有Autopilot、Cam Pilot、Robocrop等视觉导航产品和Robocrop InRow机械除草机防除行内杂草.基于光谱成像的杂草信息获取方法较适用于识别行内杂草,中、澳正联合研发微光子植物判别和杂草控制传感器.需要继续深入研究在复杂的开放式非结构的农田环境中,快速、准确地实时获取农田杂草信息技术.     

Effect of different drip irrigation regimes on sugar beet (Beta vulgaris L.) yield, quality and water use efficiency in Middle Anatolian, Turkey

Agricultural production has forced researchers to focus on increasing water use efficiency by improving either new drought-tolerant plant varieties or water management for arid and semi-arid areas under water shortage conditions. A field study was conducted to determine effects of seasonal deficit irrigation on plant root yield, quality and water use efficiency (WUE) of sugar beet for a 2-year period in the semi-arid region. Irrigations were applied when approximately 50–55% of the usable soil moisture was consumed in the effective rooting depth at the full irrigation (FI) treatment. In deficit irrigation treatments, irrigations were applied at the rates of 75, 50 and 25% of full irrigation treatment on the same day. Irrigation water was applied by a drip irrigation system. Increasing water deficits resulted in a relatively lower root and white sugar yields. The linear relationship between evapotranspiration and root yield was obtained. Similarly, WUE was the highest in DI25 irrigation conditions and the lowest in full irrigation conditions. According to the averaged values of 2 years, yield response factor (k _y ) was 0.93 for sugar beet. Sugar beet root quality parameters were influenced by drip irrigation levels in both years. The results revealed that irrigation of sugar beet with drip irrigation method at 75% level (DI25) had significant benefits in terms of saved irrigation water and large WUE, indicating a definitive advantage of deficit irrigation under limited water supply conditions. In an economic viewpoint, 25% saving of irrigation water (DI25) caused 6.1% reduction in the net income.     

Urea-SCR系统尿素喷射数据驱动预测控制研究

为了同时实现较高的NOx转化效率和较低的NH3逃逸量这一矛盾的排放控制需求,基于数据驱动预测控制技术设计了一款urea-SCR系统尿素喷射控制器。数据来自某型号柴油机台架ETC瞬态循环测试试验,控制器直接由四输入及两输出(预测输出和约束输出)耦合激励再分离得出。基于系统的实际物理特性,在控制问题描述中明确考虑了输入输出量的时域约束。考虑到相对参考无偏的控制需求,预测方程采用增量型。台架测试表明,激励工况下,控制器能够满足优化问题提出的排放控制目标;非激励瞬态工况下,对于工况变化不确定性引起的干扰,控制器具有较好的鲁棒性。     

抗烟嘧磺隆谷子品种冀谷43的选育

冀谷43是河北省农林科学院谷子研究所采用专利技术通过有性杂交方法育成的非转基因优质抗除草剂谷子新品种,兼抗拿捕净、烟嘧磺隆和咪唑啉酮除草剂。本研究总结了抗烟嘧磺隆谷子种质的创制及应用。耐药性测定结果表明冀谷43对烟嘧磺隆表现出高耐药性,鲜重抑制率低于10%。综合考虑杂草防效、产量、除草成本,生产上推荐剂量为1500ml/hm2。本研究为谷子抗除草剂育种及安全、高效地应用烟嘧磺隆进行谷田杂草防控提供理论依据。     

Assessing the options for upland livestock systems under CAP reform: Developing and applying a livestock systems model within whole-farm systems analysis

This paper presents a scenario-based analysis of the impacts of Common Agricultural Policy (CAP) reform for upland agriculture using a Welsh case-study. Specifically the paper examines the impacts of the introduction of the single-farm payment (SFP), the modulation of direct payments under Pillar I of the CAP and the increase in agri-environment payments under Pillar II. Three enterprises are examined, upland sheep rearing with lamb finishing, spring- and autumn-calving suckler-cattle with calf rearing. These enterprises are modelled under conditions in 2002/3, 2004/5 and for the reformed CAP in 2005/6. To support this analysis a livestock system model (LSM) was implemented. The model assesses alternative management regimen using a flexible state-transition approach. This simplifies the realisation and parameterisation of potentially complex management regimen. The model tracks fodder requirements to achieve targets based on defined diets. The LSM underpins whole-farm analyses of stocking-rates, labour and other resource requirements and net-farm income. From the case study the paper concludes that the impacts of the introduction of the CAP reform on the financial performance of the systems are small but negative (a net reduction of around 5% in support). The larger reduction in direct payments (15–18%) is partially offset by agri-environment measures. The paper concludes that while SFP encourages a more market-oriented outlook, the adaptive capacity within systems as they stand is very limited. There are a range of possible adaptation strategies, but for the uplands the extensification of cattle systems by reducing stock numbers and cutting back on labour seems most probable.     

An assessment of the energy inputs and greenhouse gas emissions in sugar beet (Beta vulgaris) production in the UK

Reducing the energy derived from fossil fuels within agricultural systems has important implications for decreasing atmospheric emissions of greenhouse gases, thus assisting the arrest of global warming. The identification of crop production methods that maximise energy efficiency and minimise greenhouse gas emissions is vital. Sugar beet is grown in a variety of locations and under a variety of agronomic conditions within the UK. This study identified thirteen production scenarios, representative of over 90% of the UK beet crop, which included five soil types, nine fertiliser regimes and nine crop protection strategies. The fossil energy input, the overall energy efficiency and the global warming potential (GWP) of each production scenario was assessed. This study did not consider the processing of the beet to extract sugar.The overall energy input of the UK beet crop ranges between 15.72 and 25.94 GJ/ha. It produces between 7.3 and 15.0 times as much energy in dry matter at the sugar factory gate as consumed in its production, with an average ratio of 9.7. It has an average GWP of 0.024 eq. t CO₂ per tonne of clean beet harvested, equivalent to 0.0062 eq. t CO₂ per GJ output. The energy input into each scenario was dictated largely by the energy associated with crop nutrition. The smallest energy inputs per hectare were to crops grown under organic conditions or conventional crops grown on fertile soils (clay loam, silt or peat) or sand soil with broiler manure applied. Those crops with the greatest energy input were grown on sand soil that was irrigated and had mineral fertiliser applied. Although the organic scenario grown on sandy loam soil had one of the smallest energy inputs per hectare, the low yield meant that the energy input was similar per tonne of beet harvested to the conventional crops grown on sandy loam soil. The extra distance travelled by organic beet from the farm to the factory increased the energy input per tonne above that of the conventional scenarios. The GWP was smallest for the conventional crops on the fertile peat and silt soils and greatest on the irrigated sand soils and the sandy loam soils. The organic scenario had a similar GWP to the conventional scenarios on sandy loam to the farm gate, although the greater diesel requirement for transport increased the GWP overall. The GWP per GJ of output for sugar beet in England is similar to published values for wheat.     

浅析葡萄的高产栽培技术

葡萄由于其具有极高的经济价值,所以在我国被广泛种植,文章对葡萄对环境条件的要求、施肥技术、栽植技术、嫁接技术、病虫害防治等方面进行阐述.     

Assessment of the FAO AquaCrop model in the simulation of rainfed and supplementally irrigated maize, sugar beet and sunflower

Farming in Serbia is traditionally rainfed. Analyses show that drought events of varying severity are frequent in this region, although there is no specific pattern. There is a distinct need for an objective assessment of the impact of drought on strategic field crops, to solve the dilemma whether irrigation is required or not. For this reason, and based on available field data, the FAO AquaCrop water driven model was selected to simulate yield and irrigation water use efficiency (IWUE) for three major field crops (maize, sunflower, and sugar beet), under two scenarios: (1) natural water supply and adequate supply of nutrients, and (2) supplementary irrigation and adequate supply of nutrients. The experiments presented here were conducted between 2000 and 2007 in northern Serbia, where chernozem soil is prevalent. Data of 2003 cropping seasons were used for local calibration, whereas the remaining years for validation. Results were such that local calibration resulted in very minor changes of AquaCrop coefficients (e.g., maize basal crop coefficient, sunflower harvest index, etc.). Simulated maize yield levels exhibited the greatest departure from measured data under irrigation conditions (−3.6 and 3.3% during an extremely dry and an extremely wet year, respectively). Simulated sunflower yield levels varied by less than 10% in 8 out of 10 comparisons. The most extreme variation was noted during the extremely wet year. The difference between simulated and measured values in the case of sugar beet was from −10.2 to 12.2%. Large differences were noted only in two or three cases, under extreme climatic conditions. Statistical indicators - root mean square error (RMSE) and index of agreement (d) - for all three crops suggested that the model can be used to highly reliably assess yield and IWUE. This conclusion was derived based on low values of RMSE and high values of d (in the case of maize and sugar beet 0.999 for both yield and IWUE, and in the case of sunflower 0.999 for yield and 0.884 for IWUE). It is noteworthy that under wet conditions, the model suggested that sunflower and sugar beet do not require irrigation, as confirmed by experimental research. These data are significant because they show that the AquaCrop model can be used in impartial decision-making and in the selection of crops to be given irrigation priority in areas where water resources are limited.     

Water,tillage and weed interactions in lowland tropical rice: a review

Interactions among water, tillage and weed management practices are complex, and are further complicated by soil and climatic variabilities and heterogeneities. Studies from the tropical regions on possible effects of tillage and water control on weed emergence and growth in the presence and absence of herbicides have yielded conflicting results due to site specificity. Surface ponding of water in rice (Oryza sativa L.) reduces weed emergence and growth with variable degrees of success depending upon water depth, nature of weed species and time of ponding. Most studies, however, indicate that shallow ponding for the first few weeks after planting can effectively suppress weeds. Integration of herbicide in a weed control program makes proper water management more critical. However, good water control is still lacking in most parts of tropical Asia. Investigations of various tillage intensities have revealed that invariably zero tilled soils have more weed population compared with those conventionally tilledin the absence of herbicides. Tillage may bury some weed seeds and expose others that were once deeply buried. Also, repeated tillage will uproot and bury the already germinated weeds. In a diverse weed community situation weed control is effectively achieved if tillage is combined with herbicide application, because tillage is known to enhance herbicide effectiveness. There are reports of identical rice yields being obtained under saturated and flooded water regimes, and zero and conventionally tilled soils. However, effective weed control is required for obtaining such results. Investigations of interactions of tillage intensities and water regimes with weed populations have not been adequately addressed, as most studies have been confined to quantifying competition factors in terms of critical weed population thresholds. Some studies have attempted to explain the nature of competition and its mechanisms. Of the many weed species reported to grow in rice fields, only few actually compete with rice. Generally there are only three to four weed species which are economically important for rice farmers in the tropics. It is these weeds which should be essentially controlled, although total weed control is preferred by most rice farmers. Continuous use of the same control measure in some areas may contribute to a buildup of some tolerant weed species which are difficult to control. Therefore, for effective and sustained weed control, integrated weed management with proper tillage and water control is needed.     

Productivity of yam under alternative cropping systems adopted by small-holder farmers of southeastern Nigeria

This study compares productivity of yam under mixed and sole cropping systems and determines the opportunity cost involved in the mixed cropping system preferred by small-holder farmers of southeastern Nigeria.The results show that output of yam per hectare, output/seed input ratio, as well as yield per yam crop stand, were all higher under yam sole cropping than under mixed cropping. Scarce resources of land, labour and capital were more productive under sole cropping. The opportunity cost of producing yam under a mixed corrping system was equivalent to

480·79 per hectare.Considering the labour and financial problems faced by the farmers, and given that the same level of social status is attainable by adopting either of the two cropping systems, it becomes rational to adopt sole cropping with less labour and cash requirements but higher output and returns.     

Assessing the profitability of different crop protection strategies in cotton: Case study results from Shandong Province,China

The paper compares the economic performance of different crop protection strategies in cotton including the use of transgenic varieties in Shandong Province, China. By means of a Monte Carlo simulation model a comparison was made between conventional insecticide strategies, planting of bollworm-resistant Bt varieties and a strategy of combining both technologies. To account for the observed variation in the toxin content of the Bt varieties in China, two different quality levels of Bt seed are included in the model.The data for the model are season-long records of input use and yield of 150 small-scale cotton producers in five villages in Shandong Province, which are complemented with a survey of Chinese cotton experts. Results show that the high cost pest control strategy based on expensive, good quality Bt seeds is economically inferior to low cost strategies. Scenarios for different pest population levels were included and while the use of low quality Bt seed with need-based applications of insecticides is the dominant control strategy for the normal and high pest pressure scenarios, the use of non-Bt varieties performs well under low pest pressure conditions. These results imply the need to include agro-ecosystem aspects such as pest pressure conditions and the impact of control interventions on both pests and natural enemies in the assessment of pest control strategies.     

水田株间除草机械除草机理研究与关键部件设计

针对现有水田株间除草机伤苗率高等问题,进行机理分析和改进设计,采用左、右2组弹齿盘对称安装,通过软轴带动除草弹齿盘旋转,完成除草功能。通过对除草关键部件弹齿盘的运动学和水田植物(水稻稻苗和稗草)的强度分析,建立了弹齿盘的运动学模型以及水田植物的受力模型、应力模型。通过水田植物的应力模型分析,建立了水田植物的强度条件,并根据水田植物(水稻稻苗和稗草)的物理特性、弹齿盘基本参数,获得了除草盘转动角速度、弹齿数量的取值范围,并通过室内土槽试验确定了弹齿盘转动角速度为25.1 rad/s、弹齿数量为5。通过田间性能检测,结果表明,除草率为80%、伤苗率为4.5%,均达到了农艺技术指标的要求。     

智能化作物株间机械除草技术分析与研究

非化学除草方式是生产有机农产品的前提,传统的机械中耕除草技术可有效去除行间杂草,但株间杂草密集度大且分布区域不连续,目前以人工除草为主,效率低且劳动成本高。机械除草作为化学除草的有效替代,除草高效且无化学药剂残留,符合绿色精准农业的发展要求,引起国内外众多学者的关注。为此,介绍了传统除草技术及株间除草技术的现状,重点介绍了国内外株间除草装置的关键部件与智能化系统,并分析比较了各种除草技术的优势与不足,最后对智能化作物株间机械除草技术作了总结和展望。     

茶园微耕机的设计分析

茶园的除草、施肥、松土是茶叶生产过程的重要环节,而传统的工作方式都是人工操作,作业效率低、劳动强度大。为了提高茶园的除草、松土效率,设计制造一种茶园微耕机,并对微耕机进行性能试验。试验结果表明:该微耕机耕作幅宽443mm、耕作深度153mm,旋耕刀能够有效防缠草,松土效果好,满足了茶园农艺要求;耕后表土细碎,土肥掺和均匀,满足了茶园管理要求。同时,该机可用于其它菜地、稻田旱地等除草松土作业。     

融合路面特征的大型喷雾机多工况悬架控制与试验

大型高地隙喷雾机的作业工况复杂,不同路况对悬架的性能要求不尽相同,传统悬架系统已无法满足喷雾机多工况作业的不同减振需求。为有效提高大型喷雾机各工况下的减振性能并有效降低能耗,提出了一种基于路况识别的多工况主动悬架控制系统。首先,分析喷雾机典型作业工况,建立路面特征与悬架模型的映射关系;然后,搭建喷雾机油气悬架的上下层控制系统,采用变步长萤火虫算法优化控制系统中各工况下的阻尼系数;最终将搭载该控制算法的喷雾机进行田间动态性能试验。试验结果表明,相比传统悬架,主动悬架在水泥及田间路面的行驶平顺性分别提升11.0%和22.8%,操控稳定性分别提升24.5%和3.4%。本研究所提出的控制系统可以有效解决不同工况下驾驶平顺性和操纵稳定性的矛盾关系,满足喷雾机各工况的特定减振需求。