Climate change impacts on wheat production in a Mediterranean environment in Western Australia

The environment in which crops will be grown in the future will change. CO₂ concentrations [CO₂] and temperatures (T) will probably increase and a decline of winter rainfall is predicted for south-west Australia. To be able to adapt crop systems to a changing climate it is important to know how different aspects of climate change affect agricultural production and how they interact. In a full factorial design we studied how higher T (2, 4 and 6 °C) elevated [CO₂] (525 and 700 ppm) and five different rainfall scenarios affected wheat yield and grain protein. Effects of climate change were simulated with the Agricultural Production Systems Simulator (APSIM-Nwheat) using transformed historic weather data. Fifty years of yield and grain protein concentrations were simulated for three soil types at different locations on a north–south transect within the wheatbelt of south-west Australia.

Simulation results showed that there were complex interactions between different aspects of climate change on crop systems. Effects of higher temperatures, elevated [CO₂] and changed rainfall were in general not linear and differed significantly between soil types and location. Higher [CO₂] increased yield especially at drier sites while higher temperatures had a positive effect in the cooler and wetter southern part of the region. The main difference between soil types was that heavier clay soils are most vulnerable to reduced rainfall while sandy soils were more vulnerable to higher temperatures. Elevated [CO₂] reduced grain protein concentration and lower rainfall increased protein levels at all sites. Higher temperatures could both increase and decrease protein concentrations.

In the southern, higher rainfall part of south-western Australia, yield and gross margin will increase for all likely future climate scenarios. In the drier part of the region, negative effects of 15% reduced rainfall can be compensated for by a 2 °C increase in temperature and 50% higher [CO₂] concentrations. However due to the non-linearity of climate change effects a 30% reduction in rainfall cannot be compensated for by higher temperatures and [CO₂].     

基于灰色预测模型测算农业机械化贡献率

测算出农业机械化对农业生产的贡献份额,对农业机械化投入决策具有重要的参考作用。通过采用灰色系统预测方法,建立农业产出、农业机械化投入、物质消耗、劳动力投入和土地面积投入的灰色序列模型,得出农业投入产出总体回归模型,预测农业机械化贡献率。     

The potential for systems and modelling research in pasture science in South Africa

The availability of computers has made it possible to process large volumes of complex data. This development has enabled scientists to enter the field of systems research which both analyses and synthesises complex multivariate agricultural production systems. By building models which represent real systems and by simulating the internal processes of each component of the system, systems research can be used in prediction, decision-making, developing new production methods and teaching. The potential use of modelling in the field of pasture science in South Africa deserves careful evaluation, in view of the complexity, expense and long-term nature of traditional grazing experiments. There is a place for modelling by inter-disciplinary teams in local research, in spite of the present shortcomings of this recently-developed approach.     

Simulated long-term nitrogen losses for a midwestern agricultural watershed in the United States

Adequate knowledge on the movement of nutrients under various agricultural practices is essential for developing remedial measures to reduce nonpoint source pollution. Mathematical models, after extensive calibration and validation, are useful to derive such knowledge and to identify site-specific alternative agricultural management practices. A spatial-process model that uses GIS and ADAPT, a field scale daily time-step continuous water table management model, was calibrated and validated for flow and nitrate-N discharges from a 365 ha agricultural watershed in central Iowa, in the Midwestern United States. This watershed was monitored for nitrate-N losses from 1991 to 1997. Spatial patterns in crops, topography, fertilizer applications and climate were used as input to drive the model. The first half of the monitored data was used for calibration and the other half was used in validation of the model. For the calibration period, the observed and predicted flow and nitrate-N discharges were in excellent agreement with r² values of 0.88 and 0.74, respectively. During the validation period, the observed and predicted flow and nitrate-N discharges were in good agreement with r² values of 0.71 and 0.50, respectively. For all 6 years of data, the observed annual nitrate-N losses of 26 kg ha⁻¹ for the entire simulation were in excellent agreement with predicted nitrate-N losses of 24.2 kg ha⁻¹. The calibrated model was used to investigate the long-term impacts of nitrate-N losses to changes in the rate and timing of fertilizer application. Results indicate that nitrate-N losses were sensitive to rate and timing of fertilizer application. Modeled annual nitrate-N losses showed a 17% reduction in nitrate-N losses by reducing the fertilizer application rate by 20% and switching the application timing from fall to spring. Further reductions in nitrate-N losses require conversion of row cropland to pasture and/or replacement of continuous corn or corn–soybean rotation systems with alternative crops.     

A commentary on systems studies in agriculture

Increasingly detailed research is continually adding to information on the components of agricultural systems. The effort is not being matched by synthesis of results into recipes that could be understood by farmers, nor by prediction of the effect of adopted measures. These omissions have drawn criticism not only from farmers and their financing institutions who are left to their own devices to assemble the bits and pieces, but also from research administrators and scientists who are disappointed at the lack of impact their work makes on agricultural practice.The tardiness to synthesise components into systems is traced to a number of factors. These are changing socio-economic circumstances; modern instrumentation; the intra-disciplinary approach; vague images of production systems; lack of a common language; limited resources for research and the limitations of the conventional concepts of the law of limiting factors and of the scientific method to steer research.In recent years, system simulation has been developing into a new skill endeavouring to meet the requirements of the changing scene. Studies of whole systems incorporating the use of abstract models and using mathematics as a common language, together with the calculating capacity of computers, are providing a framework into which to fit the fragments of data. By summarising such of the information as is relevant into models of systems, both lacunae and redundancies in the data are exposed. However, verification of models through more critical evaluation of postulates and processes is required before models can be used as predictive tools.Since approximation of what agricultural systems are like and how they function is sequential, integrative, quantitative, uses all relevant data from specialised research and conventional experimentation, leans heavily on experience, and is written in a universally understood language of symbols and mathematics, the system simulation approach is commended as a methodology worthy of consideration to complement other, ad hoc procedures in assembling information purposefully and in guiding scientists, farmers and other agricultural bodies as to where their priorities lie.     

Development of a system to produce maps of agricultural profit on a continental scale: An example for Australia

Policy makers in the agricultural sector are confronted with challenges which might drive land use change and ultimately agricultural profitability to a substantial degree. The challenges include questions around climate variability, demographic changes, use of land for bio-fuel production and ensuring an increase in food production. As profitability triggers many agri-business decisions, knowledge about the existing socio-economic landscape and the economic profile of a region as well as potential impacts on profits provides useful contextual information when agricultural policies are designed. Given the upcoming challenges and their associated uncertainties, it is important to ensure that a map of agricultural profit can be reproduced in a scenario and simulation setting which will allow exploring uncertainties around the impacts on agricultural profits as well. There is however currently no flexible system in operation which allows for a consistent update of a map of agricultural profits in Australia or elsewhere. This paper describes a process that has been developed to produce a map of agricultural profit for Australia for the year 2005/2006. The process involves a complex data architecture that accounts for heterogeneous information that is collected by a variety of institutions across different scales. All information can be comfortably queried and query results can be forwarded for immediate processing and subsequent visualisation in a geographic information system (GIS). To facilitate the production of profit maps in the future, the system provides flexibility regarding an update of new economic information but it can also be linked to maps that show an updated distribution of land use. A map of agricultural profit on a large scale and regular updates thereof will help understand profit trends in time and across space. It will help identifying regions that have a lower economic profile and will inform decisions regarding the design of regulatory policies. As these maps are developed using national scale data, we do not recommend using the results at the farm level but we suggest using separate catchment scale profit assessments to calibrate the national scale profit map. The proposed system is well suited to be used in various land use management and economic scenarios and will represent a step forward regarding a scenario impact assessment on agricultural profits. It will also help understand the economic benefit of land use on a large scale.     

叶片含水率推扫式高光谱成像去条纹标定法优化

由推扫式高光谱成像系统所采集的图像中会出现特有的条纹噪声,这些噪声会穿过化学计量学模型,最终出现在反映被测指标空间分布情况的可视化预测图中,干扰其空间特征的呈现及解读.以银杏叶含水率为例,基于偏最小二乘回归(PLSR)预测模型,将经去条纹标定法处理后的图像分别与原始图像及经传统均值滤波增强后的图像进行比较,研究去条纹标...     

Irrigation with brackish water under desert conditions III. Methods for achieving good germination under sprinkler irrigation with brackish water

Conventional sprinkler irrigation methods used in a Mediterranean desert climate include pre-irrigation to wet the rooting zone of the soil profile to field capacity, followed by light irrigation daily during the germination period, and thereafter by the irrigation schedule appropriate for the crop and season. When brackish water is used under the high-evaporation conditions of the desert summer, the light daily irrigations during the germination period result in rapid salinization of the seedbed and in very poor germination. However, in soils with high water infiltration rates, these problems can be averted by omitting pre-irrigation, and applying all the water thus saved for leaching of the seedbed during the germination period.

In a field experiment with tomatoes, the application of 215 mm brackish water (EC_i = 4.4 dS/m) during a 10-day period after sowing on a flat soil surface resulted in an effective leaching of salt from the upper 5 cm soil layer and in a five-fold increase in the number of germinated seedlings compared to the conventional method of irrigation with the same water. When brackish water was used with the conventional irrigation schedule, sowing in shallow furrows tripled the number of germinated seedlings compared to sowing on a flat seedbed, and the use of a mulch of wood chips quadrupled the number of germinated seedlings compared to no mulching.     

基于IBAS-BP算法的冬小麦根系土壤含水率预测模型

为在节水灌溉系统中精确测量和预测根系土壤含水率,将传统天牛须算法每次迭代过程中的一只天牛改进为一个天牛种群,建立了基于改进天牛须搜索算法优化的IBAS BP预测模型,并利用实测浅层土壤含水率数据,对深度50 cm冬小麦根系土壤含水率进行预测。结果表明,与PSO BP预测模型、GA BP预测模型以及原始BAS BP模型相比,IBAS BP模型可准确预测冬小麦根系土壤含水率,有效避免了网络陷入局部极小值的可能性,且相对误差均值仅为0.0045。     

Climate change impacts on irrigated maize in Mediterranean climates: Evaluation of double cropping as an emerging adaptation alternative

Because its relevance for the sustenance and livelihood of human systems, the assessment of the impacts that future climatic conditions may have on agricultural productivity becomes a key piece of information for agricultural scientists and policy makers.     

东亚土地经营规模变化对我国的启示-以日本、韩国和我国台湾地区为例

发展现代农业是我国新农村建设的首要任务。从我国农业发展情况看,土地规模经营问题是制约农业现代化发展的关键因素。通过对日本、韩国以及我国台湾地区扩大土地规模经营的途径进行归纳和对比,总结其经验和教训,提出对我国现代农业发展的借鉴与启示。笔者认为,我国农业土地经营规模改革应以是否促进农业生产力发展为根本依据,在尊重农民意愿的基础上,采用多种农地经营流转的方式,逐步推进农地产权流转市场化进程,从而达到加速土地经营权流转和扩大土地经营规模的目的。     

我国农业机械化宏观研究的态势分析

在对农业机械化基本内涵、农业机械化项目类别和农业机械化关键特征的概念进行辨识的基础上，从农业机械化系统分析、农业机械化与经济的关系、农业机械化贡献率的测算、农业机械化效益评价、农业机械化发展水平评价和农业机械化发展的阶段性等方面，比较全面地分析了我国农业机械化宏观研究的现状，并预测了现阶段我国农业机械化宏观研究的趋势。     

美国密西西比三角洲农业航空和精准农业技术研发现状、展望与启示

作物生产管理已经进入智慧农业阶段。智慧农业是由最先进的农业信息技术、智能装备以及大量的数据资源所驱动的先进农业科技理念。智慧农业继承了精准农业概念,把农业生产管理由机械化和信息化提高到高度自动化和智能化的农业生产管理。精准农业从上世纪八十年代的粗略监测发展到本世纪10年代的详细监测和控制。在精准农业的发展过程中,农业航空在作物保护和肥料施用方面起到了关键的作用。而在作物保护和肥料精准施用方面,基于全球导航产生的带有空间信息遥感数据配方图是至关重要的。随着现代化农业的发展,农业航空会因更有效的土壤和植物健康监测和更加快速的机电系统响应,在推进精准农业实际应用上显得越发重要。本文具体从美国最重要的农业地区之一密西西比三角洲出发,总体介绍了农业航空在精准农业向智慧农业迈进过程中的状况。重点介绍了美国农业部在密西西比三角洲地区在航空应用技术和低空遥感方面的研发工作;为发展新一代精准农业和智慧农业,进一步研发农业航空技术的问题、挑战和机会进行了讨论;最后提出了中国发展智慧农业建议。     

Comparison of soil water content and corn yield in furrow and conventional ridge sown systems in a semiarid region of China

Water deficits and unusually warm soil temperatures can adversely affect conventional ridge sown systems. Increasingly serious water and temperature issues associated with global climate change may be problematic in the future, particularly in semiarid regions. This study explored the soil water and crop yield benefits of switching the sowing location of corn from ridges to furrows. Experiments were conducted over three years. Corn was grown in shallow furrow (SF) and deep furrow (DF) sown treatments until the V8 stage (eight visible leaf collars). New ridges were then built over the existing furrows. Grain yield was found to be higher in the SF and DF sown treatments than in a conventional ridge sown treatment (CR), especially in drought years. Switching sowing position from ridge to furrow could increase corn yield, directly, by improving soil moisture early in the growing season and, indirectly, by stimulating the growth of resource-capturing organs (e.g., leaves and roots). This simple and efficient approach to crop production in semiarid climates may be practical for the management of numerous agricultural systems, particularly those that are resource-limited, with greater vulnerability to the effects of global climate change.     

Agricultural systems in Ethiopia— A review article

Amare Getahun's (1978) paper on agricultural systems in Ethiopia is one of the few attempts to classify agricultural systems in Ethiopia into (a) the highland mixed farming system, (b) low plateaux and valley mixed agriculture, (c) pastoral livestock production of the arid and semi-arid zones and (d) commercial agriculture, and to describe the main characteristics of each system. However, it is not clear what criteria have been used to classify the different agricultural regions into the four general categories developed by Amare Getahun. This review paper discusses agricultural systems by applying the ecological systems approach to agricultural development within the framework of a political economy analysis as a means of evaluating agricultural development strategies.     

新疆兵团农机总动力预测模型的研究

为了提高新疆兵团农机总动力预测模型的精度,获得更加可靠的预测结果,针对回归模型的多重共线性问题及灰色模型仅含有指数增长趋势的问题,基于2007-2014年农机动力的相关数据,建立了主成分回归和灰色回归两种预测模型。对两种模型的预测精度进行比较分析,结果表明:主成分回归模型和灰色回归模型预测值的平均相对误差分别为0.57%、0.46%,灰色回归预测模型的精度较高,可以较真实地反映新疆兵团农机总动力的变化趋势。应用该模型进行预测,得到了新疆兵团农机总动力未来5年的预测值。     

基于专利分析的农用无人机技术发展趋势

近几年,全球农用无人机技术专利申请每年持续高速增长,在全球申请人排名中,前10名均是中国申请人,中国企业与高校遥遥领先,申请专利主要以作业管理技术为主,这与农用无人机的应用场景紧密相连.为研究农用无人机技术发展趋势,针对农用无人机技术领域在2009年之后的专利申请进行了统计分析.从总体趋势、地域分布、主要竞争者和技术构...     

Increasing profits and reducing risks in crop production using participatory systems simulation approaches

The development of cropping systems simulation capabilities world-wide combined with easy access to powerful computing has resulted in a plethora of agricultural models and consequently, model applications. Nonetheless, the scientific credibility of such applications and their relevance to farming practice is still being questioned. Our objective in this paper is to highlight some of the model applications from which benefits for farmers were or could be obtained via changed agricultural practice or policy. Changed on-farm practice due to the direct contribution of modelling, while keenly sought after, may in some cases be less achievable than a contribution via agricultural policies. This paper is intended to give some guidance for future model applications. It is not a comprehensive review of model applications, nor is it intended to discuss modelling in the context of social science or extension policy. Rather, we take snapshots around the globe to ‘take stock’ and to demonstrate that well-defined financial and environmental benefits can be obtained on-farm from the use of models. We highlight the importance of ‘relevance’ and hence the importance of true partnerships between all stakeholders (farmer, scientists, advisers) for the successful development and adoption of simulation approaches. Specifically, we address some key points that are essential for successful model applications such as: (1) issues to be addressed must be neither trivial nor obvious; (2) a modelling approach must reduce complexity rather than proliferate choices in order to aid the decision-making process; (3) the cropping systems must be sufficiently flexible to allow management interventions based on insights gained from models. The pro and cons of normative approaches (e.g. decision support software that can reach a wide audience quickly but are often poorly contextualized for any individual client) versus model applications within the context of an individual client's situation will also be discussed. We suggest that a tandem approach is necessary whereby the latter is used in the early stages of model application for confidence building amongst client groups. This paper focuses on five specific regions that differ fundamentally in terms of environment and socio-economic structure and hence in their requirements for successful model applications. Specifically, we will give examples from Australia and South America (high climatic variability, large areas, low input, technologically advanced); Africa (high climatic variability, small areas, low input, subsistence agriculture); India (high climatic variability, small areas, medium level inputs, technologically progressing; and Europe (relatively low climatic variability, small areas, high input, technologically advanced). The contrast between Australia and Europe will further demonstrate how successful model applications are strongly influenced by the policy framework within which producers operate. We suggest that this might eventually lead to better adoption of fully integrated systems approaches and result in the development of resilient farming systems that are in tune with current climatic conditions and are adaptable to biophysical and socio-economic variability and change.     

农业知识图谱技术研究现状与展望

在当前农业信息化的发展进程中,多数农业子领域面临着数据资源分散、信息整合难度大、知识利用效率低等问题。作为近年来新兴的一种知识表示技术,知识图谱已在部分农业特定领域展现出了强大的语义推理和数据整合能力,同时帮助一些农业上层应用提高了性能。为系统总结近年来农业知识图谱构建与应用方面的研究成果,本文首先阐述了知识图谱基础和农业知识图谱的构建流程,并从本体建模、信息抽取、知识融合以及知识加工4方面总结了构建农业知识图谱所涉及的关键技术。将当前农业知识图谱的应用分为信息检索、问答系统、推荐系统、专家诊断系统和作物预测5方面,并对这些应用工作进行了梳理。最后,对当前农业知识图谱的研究现状进行了总结,并认为未来农业知识图谱可以从多模态知识推理、强时效性知识更新、多语言知识查询、跨领域数据融合以及子领域知识图谱构建等方面加以研究。     

Simulation in ergonomics,in particular in agriculture and forestry: Report on the international symposium at Åas,Norway 19–21 September, 1977

The symposium was convened to provide a forum for an international exchange of papers describing current agricultural ergonomic research and interests. These multidisciplinary meetings of medical, engineering, agricultural and other scientists ensure that those working in countries where close and specialised liaison does not yet exist can return home with fresh examples of the benefits. The medical participants are able to report on the clinical effects of farming systems while the engineering and ergonomist members can report on their efforts to improve systems—prevention of stress being better than cures for the symptoms of excessive stress: the ideal, stress-free farm system being so far only an illusionary concept.