土地整治田间污染防控工程体系初探

为了降低农田非点源污染的程度与区域生态环境风险,提高区域农业生态环境安全程度。在对现有土地整理工程技术手段进行综合集成的基础上,结合农业非点源污染防控相关理论,设计了生态型田间污染防控的工程构件,构建区域农田污染整治工程规划方案,并将其应用到以江苏省环太湖地区的典型土地整治项目中。结果表明：基于田间污染防控设计、承泄区污染防控设计以及渠首污染防控设计的土地整治田间污染防控工程体系是现有土地整治工程技术的有益补充,对农田非点源污染具有一定的防控作用,提高了区域农地可持续利用程度。     

A cropping system assessment framework—Evaluating effects of introducing legumes into crop rotations

Methods are needed for the design and evaluation of cropping systems, in order to test the effects of introducing or reintroducing crops into rotations. The interaction of legumes with other crops (rotational effects) requires an assessment at the cropping system scale. The objective of this work is to introduce a cropping system framework to assess the impacts of changes in cropping systems in a participatory approach with experts, i.e., the integration of legumes into crop rotations and to demonstrate its application in two case studies. The framework consists of a rule-based rotation generator and a set of algorithms to calculate impact indicators. It follows a three-step approach: (i) generate rotations, (ii) evaluate crop production activities using environmental, economic and phytosanitary indicators, and (iii) design cropping systems and assess their impacts. Experienced agronomists and environmental scientists were involved at several stages of the framework development and testing in order to ensure the practicability of designed cropping systems. The framework was tested in Västra Götaland (Sweden) and Brandenburg (Germany) by comparing cropping systems with and without legumes. In both case studies, cropping systems with legumes reduced nitrous oxide emissions with comparable or slightly lower nitrate-N leaching, and had positive phytosanitary effects. In arable systems with grain legumes, gross margins were lower than in cropping systems without legumes despite taking pre-crop effects into account. Forage cropping systems with legumes had higher or equivalent gross margins and at the same time higher environmental benefits than cropping systems without legumes. The framework supports agronomists to design sustainable legume-supported cropping systems and to assess their impacts.     

安徽省粮食生产能力研究与分析

安徽省粮食丰产科技工程中粮食作物的产量是当前自然和技术条件下可以实现的产量,用该单产水平计算安徽省粮食生产能力更具现实意义。本文以全省13个农业生态小区为研究单元,确定了能够充分发挥当地气候生产潜力的种植制度;并以粮食丰产科技工程中粮食作物试验产量为基础,计算了各农业生态小区粮食生产能力和总的粮食生产能力。研究结果表明: 全省粮食平均单产能力为8029.47kg•hm-2,约是近3年安徽省粮食实际单产的1.37倍;全省粮食总生产能力为483.62亿kg,每年能为安徽省增加粮食产量近158.93亿kg。     

A methodology for multi-objective cropping system design based on simulations. Application to weed management

Weeds are harmful for crop production but important for biodiversity. In order to design cropping systems that reconcile crop production and biodiversity, we need tools and methods to help farmers to deal with this issue. Here, we developed a novel method for multi-objective cropping system design aimed at scientists and technical institutes, combining a cropping system database, decision trees, the “virtual field” model FlorSys and indicators translating simulated weed floras into scores in terms of weed harmfulness (e.g. crop yield loss, weed-borne parasite risk, field infestation), weed-mediated biodiversity (e.g. food offer for bees) and herbicide use intensity. 255 existing cropping systems were simulated with FlorSys, individual indicator values were aggregated into a multi-performance score, and decision trees were built to identify combinations of management practices and probabilities for reaching performance goals. These trees are used to identify the characteristics of existing cropping systems that must be changed to achieve the chosen performance goals, depending on the user's risk strategy. Alternative systems are built and simulated with FlorSys to evaluate their multi-criteria performance. The method was applied to an existing oilseed rape/wheat/barley rotation with yearly mouldboard ploughing from Burgundy which was improved to reconcile weed harmfulness control, reduced herbicide use and biodiversity promotion, based on a risk-minimizing strategy. The best alternative replaced a herbicide entering plants via shoot tips (during emergence) and roots after barley sowing by a spring herbicide entering via leaves, introduced crop residue shredding before cereals and rolled the soil at sowing, which reduced the risk of unacceptable performance from 90% to 40%. When attempting to reconcile harmfulness control and reduced herbicide use, the best alternative changed the rotation to oilseed rape/wheat/spring pea/wheat, replaced one herbicide in oilseed rape by mechanical weeding, delayed tillage before rape and applied the PRE herbicide before oilseed rape closer to sowing. This option reduced the risk of unacceptable performance to 30%. None of the initial or alternative cropping systems succeeded in optimal performance, indicating that more diverse cropping systems with innovative management techniques and innovative combinations of techniques are needed to build the decision trees. This approach can be used in workshops with extension services and farmers in order to design cropping systems. Compared to expert-based design, it has the advantage to go beyond well-known options (e.g. plough before risky crops) to identify unconventional options, with a particular focus on interactions between cultural techniques.     

Factors of winter wheat yield robustness in France under unfavourable weather conditions

To face increasing uncertainties, future farming systems must be sustainable not only under average conditions but also in extreme climatic and economic situations. Various concepts such as stability, robustness, vulnerability or resilience have been proposed to analyze the ability of agricultural systems to adapt to changing production conditions. The operational effectiveness of these concepts remains nevertheless limited. In this paper, we developed an original analytical framework allowing characterizing and quantifying crop yield robustness, as well as identifying agricultural practices linked to cropping systems differentiated according to their robustness pattern. This framework was applied to 2300 bread wheat plots belonging to 145 cropping systems in various regions of France over the period 2011–2014. The analysis was performed at the scale of the cropping system. In a first step, we defined a regression statistical model allowing us to link wheat yield variability to an index of abiotic perturbations constructed using the STICS agronomic model; the cropping systems were taken into account through the use of dummy variables. In a second step, the different cropping systems were positioned within four quadrants using the regional average wheat yield in conditions of average abiotic perturbations and the regional average estimated robustness to abiotic perturbations as cut-offs for the quadrants. In a third step, the cropping systems of the different spaces defined by the four-quadrant approach were compared on the basis on three types of agronomic practices, i.e., management intensification, rotation and heterogeneity practices. Empirical results show that abiotic perturbations had an impact on wheat yield variability. This impact differed from one system to another which means that there is a ”cropping system effect” of abiotic perturbations on wheat yield robustness. Several agronomic practices allowed differentiating high versus low wheat yield cropping systems. High yield cropping systems relied more intensively on chemical inputs (fertilizers and pesticides) and used more diversified rotations, with more frequently legumes as preceding crops and a lower frequency of cereals. Fewer agronomic practices allowed differentiating robust versus sensitive wheat cropping systems. In addition to the sowing date (later for robust systems) and the sowing density (greater), these practices were essentially linked to spatial adjustments of the sowing date, total pesticide use, variety earliness at heading stage and variety disease resistance.     

Geostatistical interpolation and aggregation of crop growth model outputs

Many crop growth models require daily meteorological data. Consequently, model simulations can be obtained only at a limited number of locations, i.e. at weather stations with long-term records of daily data. To estimate the potential crop production at country level, we present in this study a geostatistical approach for spatial interpolation and aggregation of crop growth model outputs. As case study, we interpolated, simulated and aggregated crop growth model outputs of sorghum and millet in West-Africa. We used crop growth model outputs to calibrate a linear regression model using environmental covariates as predictors. The spatial regression residuals were investigated for spatial correlation. The linear regression model and the spatial correlation of residuals together were used to predict theoretical crop yield at all locations using kriging with external drift. A spatial standard deviation comes along with this prediction, indicating the uncertainty of the prediction. In combination with land use data and country borders, we summed the crop yield predictions to determine an area total. With spatial stochastic simulation, we estimated the uncertainty of that total production potential as well as the spatial cumulative distribution function. We compared our results with the prevailing agro-ecological Climate Zones approach used for spatial aggregation. Linear regression could explain up to 70% of the spatial variation of the yield. In three out of four cases the regression residuals showed spatial correlation. The potential crop production per country according to the Climate Zones approach was in all countries and cases except one within the 95% prediction interval as obtained after yield aggregation. We concluded that the geostatistical approach can estimate a country’s crop production, including a quantification of uncertainty. In addition, we stress the importance of the use of geostatistics to create tools for crop modelling scientists to explore relationships between yields and spatial environmental variables and to assist policy makers with tangible results on yield gaps at multiple levels of spatial aggregation.     

Challenges of breeding potato cultivars to grow in various environments and to meet different demands

The potato (Solanum tuberosum L.) is cultivated all year round in Japan by using four types of cropping: summer and winter croppings, and double cropping in spring and fall. In each cropping season, growth conditions such as temperature, day length, and growing period, differ drastically; thus, different cultivars adapted to each environment are required. Breeding stations are located in both summer cropping areas and double cropping areas, and cultivars suitable for each cropping system are developed. The required cultivars differ according to cropping type and according to use such as table use, food processing, and starch production. The qualities necessary for each purpose differ and are therefore evaluated accordingly. Improvements in pest and disease resistance and in yield abilities are important as common breeding targets for all purposes. To develop potato cultivars that meet different needs, breeders have continued efforts to improve these traits. In this review, we introduce our approaches to developing new potato cultivars. We also discuss problems predicted in the future and introduce our efforts on broadening genetic diversity.     

Sustainability of European maize-based cropping systems: Economic,environmental and social assessment of current and proposed innovative IPM-based systems

There is strong social and political pressure to reduce pesticide use in European agriculture. Evaluating the sustainability of cropping systems is a complex task due to the conflicting objectives underlying its economic, social and environmental dimensions. Multi-criteria assessment of different Integrated Pest Management (IPM) scenarios and evaluation of the most sustainable options at regional, national and European level is essential. Within the EU Network of Excellence ENDURE, two expert-based surveys were conducted (i.e. interviews), where experts from four European regions (northern region, Denmark and The Netherlands; central-eastern, Tolna and Békés counties in Hungary; south-western, Ebro Valley in Spain; southern, Po Valley in Italy) determined which are the main current maize-based cropping systems (MBCSs) in their region and proposed innovative IPM-based systems. The DEXiPM^® (DEXi Pest Management) model for arable cropping systems was used to evaluate and compare the economic and environmental sustainability of these systems. The social sustainability was evaluated by adapting indicators of this model to the specificities of maize systems. The assessments showed that all innovative rotated MBCSs proposed in the four regions can have a higher environmental sustainability than and maintain the same economic sustainability as current rotated systems. These cropping systems are thus acceptable for testing under “real” field conditions. Only the innovative continuous maize system proposed in the central-eastern region was both economically and environmentally more sustainable than the current system. All innovative systems had a positive impact on work safety but according to local expert opinion producers and consumers are not ready to implement them or to accept their higher-priced products, with the exception of consumers in the northern region. These results suggest the need for European and regional policies to encourage the adoption of innovative rotated MBCSs that have positive agronomic and environmental impact through IPM implementation. The major constraints that inhibit this adoption were predominantly relating to (1) the lack of access that farmers have to the practical knowledge needed to effectively manage these systems and (2) the insufficient consumer awareness and acceptance of product improvements associated with IPM. To overcome these constraints supportive policy environments, well-functioning knowledge management systems (including good farmer support networks) and effective marketing is required.     

Creating the data basis to adapt agricultural decision support tools to new environments,land management and climate change—A case study of the RiceAdvice App

Increasing demand for land to ensure human food security in the future has already impelled agricultural production into marginal areas. The environmental conditions found there have a more pronounced impact on agricultural productivity than in the systems used so far under favourable conditions. In addition to this challenge, climate change is expected to increase the unreliability of weather conditions (through increased variability and occurrence of extremes) for farmers considerably. This unreliability is even more serious in developing countries’ farming system where food security is vulnerable. Current efforts in digitalization offer great possibilities to improve farmers` decision-making processes. A wide range of online tools and smartphone applications is available to support both agricultural extension services and smallholder farmers alike. These apps are often parameterized and validated to certain environments and are troubled when applied to new geographical locations and different environmental conditions. We have conducted field trials to demonstrate potential methods to close knowledge gaps in the data background for one of these apps, RiceAdvice, concerning three key aspects: shifting of cropping calendar, adjustment of fertilizer management and genotype selection. Sites in Ethiopia, Madagascar and Rwanda were selected to represent altitudinal gradients, with overlapping elevations reflecting differences in temperature to enable cross-country comparisons. Planting dates were distributed throughout three calendar years, with continuous iterative planting dates taking place in Madagascar, in- and off-season planting dates in Rwanda with different fertilizer applications, and one planting date during each rainy season in Ethiopia with different management options. With these trials, we have been able to identify key data sets needed for the adaptation of agricultural decision support tools to new environments. These include the assessment of climatic constraints on innovations to cropping calendars (e.g. double cropping), informed selection of alternative varieties able to complete crucial parts of their phenological development to avoid temperature-related stress inducing, for example spikelet sterility in rice in late development stages and the effectivity of potential innovations in fertilizer management strategies.     

Assessing the sustainability of cropping systems in single- and multi-site studies. A review of methods

The multiple new challenges facing agriculture require the development of innovative cropping systems with high environmental, economic and social performances. Many research programmes are currently focusing on the design of such cropping systems. Some include the multicriteria assessment of cropping systems by diverse methods and approaches. Some of these research programmes are supported by experimental or farmers’ networks, generating new opportunities for data analysis and raising new research and methodological questions. In this article, we provide an overview based on a review of 56 articles, comparing the various methods for sustainability assessment in single- and multi-site studies. Articles were classified according to three characteristics: (i) their objectives, (ii) the study design (single- vs. multi-site), (iii) the type of system assessed (fictitious vs. real). Our analysis was structured around four items: (i) the variables used to describe cropping systems and production situations and the use of these variables in the assessment process, (ii) the criteria and associated indicators assessed, (iii) the methods used to explore multiple aspects of the performance of cropping systems, (iv) the use of reference values. We identified key points to be taken into account in multi-site studies. The application of the proposed guidelines to experimental networks should facilitate the identification of high-performance cropping systems and the identification of the drivers of cropping system performance.     

土地整理前后耕地质量变化的实证分析

从科学发展观来看,耕地在数量上的扩张是有限的,但在提升耕地质量方面却具有相对大的空间。土地开发整理的基本功能是有效补充耕地面积、提高粮食综合生产能力、改善农业生态环境质量、促进土地集约化利用和加快农村经济社会发展的速度,其本质就是有效提高耕地质量。笔者根据项目区土地整理初步工程设计,结合农用地分等成果,对土地整理前后耕地质量变化情况做出评价,使土地开发整理项目实现重耕地数量到重耕地质量的转变。     

Changes in Cultivated Land Resources and Grain Potential in Mainland China between 1996 and 2007

Analysis of recent changes in the amount and nature of cultivated land and grain potential, and the impacts of these changes on grain security in mainland China provides vital information for revising and developing strategies regarding protection of cultivated land and national grain security. This study examined changes in the area of cultivated land and in grain potential in agro-ecological zones using the "change rate" method. Agro-ecological subzones were used as the basic units and agro-ecological zones as the research units. We then studied changes for all of mainland China using the "gravity centre model" and analyzed the structural change of cultivated lands in each agro-ecological zone to investigate the changes in detail. The results show that both cultivated land and grain potential in mainland China decreased from 1996 to 2007. The structural and quantitative changes in each zone have caused the shift of the gravity centres of cultivated land and grain potential in mainland China to the northeast. Unfortunately, it is unlikely that natural and economic resources can keep up with this change. Although a large gap remains between the grain potential and the actual grain yield, the rapid loss of grain potential and the direction of change pose great threats to grain security. To ensure comprehensive grain security in China, it is vital to rethink the regional patterns of grain production according to natural conditions without jeopardising cultivated land protection(quantitative and qualitative), and consider the direction of cultivated land use and reconstruction according to local natural conditions, water and soil resources, and the level of economic development, and then work steadily to improve the grain potential.     

Designing cropping systems for efficient use of limited water in southern Australia

There has been continuous change in the systems of cereal production in southern Australia where the climate is semi-arid with moderately wet winters and hot dry summers. At the outset wheat (c. 1840) was grown in continuous culture as the land was gradually cleared for cropping, but yields declined to uneconomic levels by 1900. That system was then replaced with fallow-wheat rotations, and using phosphorus fertilizer, yields recovered, but not to the original level. From 1945, the high profitability of sheep production encouraged improvement of legume-based pastures and the introduction of pasture-crop sequences – ley-farming. Productivity was greatly increased and the yield of wheat crops regained the original level. But such were the rates of acidification and salinization of soil that reduced productivity and, in the case of salinity, reduced stream quality and threatened adjacent natural ecosystems. This ley-farming system was used until the late 1980s when prices for wool fell dramatically, and farmers reduced sheep numbers and intensified cropping. The thrust since then has been to design cropping systems that are economically as well as environmentally acceptable with salinity control as the major objective. There is now a search for systems that use more water to reduce drainage through the soil and lower saline water tables. A major contribution is the much restricted use of fallow but summer active plants are also required to provide a soil water storage buffer to retain autumn–winter rainfall. New systems under evaluation include herbaceous perennials such as lucerne that are readily integrated into a crop-livestock system and agroforestry combinations with various trees. The design and appropriate distribution of the new systems is aided by remote sensing techniques to locate areas of saline discharge and linkages to zones of groundwater recharge, geographical information systems to arrange the data for land system analysis, and computer models of crops and cropping systems. There is a substantial challenge for farmers, agronomists and others to identify and assess suitable new systems and to bring the public into the debate and into the solution.     

河北省柏乡县土地整理项目的碳排放效应研究

为研究土地整理项目中的碳排放效应,明确土地整理的碳排放及其测算方法,分析土地整理碳减排潜力,以河北省柏乡县固城店镇土地整理项目区为研究区域,基于能源消费及土地利用变化,采用IPCC清单法,分析土地整理施工工程中包含土地平整工程、灌溉和排水工程、田间道路工程以及农田防护工程4个方面的碳排放及区域土地利用变化导致的碳排放。结果表明：柏乡县土地整理项目能源消费导致的碳排放总量为469.77 tC,土地平整工程的碳排放比例最大,高达78.44%,田间道路工程及灌溉和排水工程分别占15.69%,5.86%。从单位投资额碳排放量和单位投资比率的碳排放比例上看,田间道路工程和灌溉与排水工程投资的生态效应优于土地平整工程。柏乡县土地整理导致的土地利用变化使得区域土壤和植被碳储量增加了748.58 tC,其中未利用土地的碳储量变化最大。土地利用结构调整后增加的碳储量是整个施工过程中的碳排放量的1.59倍。柏乡县土地整理后项目区碳储量增加了278.81 tC,表现出碳汇效应。研究结果表明,为了降低土地整理的碳排放量,应当减少土地平整工程量,提倡使用清洁型燃料,并优先考虑碳密度较低的地类作为耕地来源,并在耕种过程中减少化肥和农药施用量,提高耕地产能。     

交替灌溉对西北绿洲区小麦间作玉米水分利用的影响

受水资源不足的严重制约,西北绿洲区以间作套种为主体的多熟种植面积被持续压缩,使单位耕地产出率和光能利用率明显下降,间作节水理论和技术研究亟待开展。交替灌溉技术节水和提高水分利用效率的作用已得到大量验证,但该技术应用到间作中能否产生节水、增效作用,缺乏理论依据。2006—2008年,在甘肃河西走廊干旱荒漠绿洲区进行田间试验,探讨了交替灌溉对小麦间作玉米产量、耗水量和水分利用效率的影响。结果表明,与单作相比,交替灌溉小麦间作玉米可显著提高土地利用效率(LER),LER达到1.22~1.52。交替灌溉与传统灌溉间作相比,LER差异不显著;对间作小麦的产量效应不显著,但使间作玉米的产量提高11.4%~36.4%,混合产量平均提高12.9%。与传统灌溉间作相比,交替灌间作未显著增加作物的耗水量,与单作小麦、单作玉米的加权平均相比高1.2%~19.4%。交替灌溉小麦间作玉米的WUE较单作小麦高12.0%~71.4%、较单作玉米高10.6%~37.8%、较传统灌小麦间作玉米高0.9%~22.5%。在河西绿洲灌区,小麦间作玉米上应用交替灌溉技术具有节水和提高WUE的可行性。     

A trait-based characterization of cover plants to assess their potential to provide a set of ecological services in banana cropping systems

Cover plants are one of the means to increase the functional biodiversity of fields and to enhance the ecological functions of the communities. However, the design of cropping systems including cover plants relies largely on expert knowledge. There is a lack of methods to select the best suited cover plants according to their role in the agrosystem. We propose to use functional traits to select cover plants suited to sustain ecological services in the banana agrosystems of the French West Indies. Our objectives were (i) to characterize a collection of cover plants on a trait basis, according to their potential to provide the services expected in a banana agrosystem and (ii) to discuss the potential use of this characterization for the design of innovative multi-species banana cropping systems. In these systems, four main services are targeted, i.e. controlling weeds, controlling plant-parasitic nematodes, improving soil fertility and particularly N availability, and avoiding competition with banana for resource acquisition. Three experiments were conducted, under field and controlled conditions, to evaluate the potential of a collection of 28 tropical cover plants to achieve the functions related to these services. For each cover plant, a functional profile was constructed from a combination of plant traits that are easy to assess experimentally. It described plants’ potential to achieve the functions expected in a banana agrosystem. Functional profiles required for cover plant usages were also identified. The comparison of the plant functional profiles and the functional profiles required for their usages enabled us to select the best suited plants for each usage. However, these functional profiles rarely corresponded, meaning that a cover plant is rarely sufficient to achieve all the functions required for a usage. Functional complementarities obtained by the mixture of different species of cover plants are thus often required. Compared to classical approaches of innovative cropping system design based on the experimental testing of spatial and temporal plant combinations, such a trait-based approach saves time by focusing on a shortlist of cover plants best suited according to their functions in the agrosystem.     

PRACT (Prototyping Rotation and Association with Cover crop and no Till) – a tool for designing conservation agriculture systems

Moving to more agroecological cropping systems implies deep changes in the organization of cropping systems. We propose a method for formalizing the process of innovating cropping system prototype design using a tool called PRACT (Prototyping Rotation and Association with Cover crop and no Till) applied to a Malagasy case study. The input information for PRACT is comprised of: (i) crop and cover crop adaptation to biophysical conditions, (ii) agroecological functions of the cover crops, (iii) crop production, (iv) association possibilities between crop and cover crop, and (v) agroecological functions of the cropping system. All the information was derived from expert knowledge developed over more than 12 years of agronomic experiments in Madagascar. The final output from PRACT is a list of cropping systems, i.e., crop and cover crop associations and their sequences over three years. These cropping systems are characterized by their potential agroecological functions and crop production. The PRACT model selects a list of cropping systems taking into account the above information by using elaborate rules governing the intercropping and sequences between crops and cover crops. Examples of the outcomes of model simulations are provided for four different kinds of field. Taking into account the range of potential crops and cover crops, the number of cropping systems that was theoretically possible for the different field types ranged from 19,683 to 2.98 ×  10¹³. In a first step, PRACT reduced this number by a factor of up to 28 times to propose possible cropping systems. To do so, cropping systems are selected in terms of the biophysical requirements of plants, plant compatibility and agronomic rules. Not all of these systems are suitable for every farmer. Thus using PRACT output, a second cropping system selection step can be taken based on these cropping system characteristics, i.e., crop production and agroecological functions. By doing so the number of cropping systems selected can reach a reasonable value that can be handled by technicians and farmers. Possible uses and further development of the tool are discussed.     

Evolution in crop–livestock integration systems that improve farm productivity and environmental performance in Australia

Australian farming systems have an enduring history of crop–livestock integration which emerged in the face of high climate variability, infertile soils and variable landscapes. Ley farming systems with phases of shorter annual legume pasture phases with cereal crops predominate but, emerging sustainability issues and the need to manage risk is driving ongoing innovation in crop–livestock integration. We discuss the recent evolution of selected innovations that integrate crop and livestock production and their impacts on farm productivity, sustainability and business risk. Dual-purpose use of cereals and canola (Brassica napus) for forage during the vegetative stage while still harvesting for grain is now practiced throughout southern Australia's cropping zone. This practice provides risk management benefits, diversifies crop rotations, reduces pressure on other feed resources and can significantly increase both livestock and crop productivity from farms by 25–75% with little increase in inputs. Sacrificially grazing crops when expected grain yield is low and/or livestock prices are attractive relative to grain provides further flexibility in crop–livestock management systems vital for business risk management in a variable climate. Replacing annual pastures with perennial pasture phases in rotation with crops can provide a range of benefits including improved hydrological balance to reduce dryland salinity, subsoil acidification and water-logging, provide a management tool for herbicide-resistant or problem weeds, improved soil nutrient and carbon stocks as well as increased livestock productivity by filling feed gaps. In some environments, integration of perennial forages in mixtures with cropping, such as alley cropping and inter-cropping, also provide options for improving environmental outcomes. These practices are all innovations that provide flexibility and enable tactical decisions about the mix of enterprises and allocation of land and forage resources to be adjusted in response to climate and price. We discuss these innovations in the context of the emerging constraints to crop–livestock integration in Australia including the continuing decline in labour availability on farms and increasing management skill required to optimise enterprise profitability.     

论粮食主产区农业生态环境的恢复与重建--以山东省聊城市为例

粮食主产区对维护国家粮食安全起着关键作用,其生态安全问题与区域农业可持续发展息息相关。以聊城市为例,初步调查和分析了农业生态环境现状,指出区域内土地退化有增无减、地表水环境不良、农业面源污染严重、乡镇工业布局混乱是目前存在的主要问题,从主观因素和客观因素两方面剖析了聊城农业生态环境恶化的原因,进而提出只有加强管理和宣传力度,完善基础设施建设,加强退化土地治理,建设农业标准化基地,推进循环农业,提高农民素质,建立科技推广网络,才能恢复与重建有利于粮食主产区农业可持续发展的农业生态环境。