A flexible approach to managing variability in grain yield and nitrate leaching at within-field to farm scales

We up-scaled the APSIM simulation model of crop growth, water and nitrogen dynamics to interpret and respond to spatial and temporal variations in soil, season and crop performance and improve yield and decrease nitrate leaching. Grain yields, drainage below the maximum root depth and nitrate leaching are strongly governed by interaction of plant available soil water storage capacity (PAWC), seasonal rainfall and nitrogen supply in the water-limited Mediterranean-type environment of Western Australia (WA). APSIM simulates the interaction of these key system parameters and the robustness of its simulations has been rigorously tested with the results of several field experiments covering a range of soil types and seasonal conditions in WA. We used yield maps, soil and weather data for farms at two locations in WA to determine spatial and temporal patterns of grain yield, drainage below the maximum root depth and nitrate leaching under a range of weather, soil and nitrogen management scenarios. On one farm, we up-scaled APSIM simulations across the whole farm using local weather and fertiliser use data and the average PAWC values of soil type polygons. On a 70 ha field on another farm, we used a linear regression of apparent soil electrical conductivity (EC_a) measured by EM38 against PAWC to transform an EC_a map of the field into a high resolution (5 m grid) PAWC map. We then used regressions of simulated yields, drainage below the maximum root depth and nitrate leaching on PAWC to upscale the APSIM simulations for a range of weather and fertiliser management scenarios. This continuous mapping approach overcame the weakness of the soil polygons approach, which assumed uniformity in soil properties and processes within soil type polygons. It identified areas at greatest financial and environmental risks across the field, which required focused management and simulated their response to management interventions. Splitting nitrogen applications increased simulated wheat yields at all sites across the field and decreased nitrate leaching particularly where the water storage capacity of the soil was small. Low water storage capacity resulted in both low wheat yields and large leaching loss. Another management option to decrease leaching may be to grow perennial vegetation that uses more water and loses less by drainage.Paper from the 5th European Conference on Precision Agriculture (5ECPA), Uppsala, Sweden, 2005     

基于SALUS与WebGIS整合的作物生长模拟

SALUS是较为著名的土地可持续使用系统模型，实现了一种基于WebGIS整合SALUS的作物生长仿真系统。详细阐述了数据库和相关功能模块的整合方法，改善了SALUS模型在空间数据处理与仿真结果视觉化的能力。可以让使用者清晰的掌握土壤、天气、灌溉量、施肥量等多种因素对农作物产量的影响，为农作物实施相关的增收管理措施提供了一定的科学依据。并提出了相应的整合方案为实际构建基于WebGIS的作物生长仿真系统提供了一定的技术支撑。     

未来气候条件下秸秆还田和氮肥种类对夏玉米产量及土壤氨挥发的影响

【目的】秸秆还田配施氮肥可以提高作物生产力,但在气候变化条件下,不同管理措施对夏玉米农田氮素利用存在很大的不确定性。明确在未来气候条件下秸秆还田与氮肥种类对夏玉米产量和土壤氨挥发的影响,以应对气候变化。【方法】利用DNDC模型预测未来不同情景下,秸秆还田和不同氮肥种类对关中地区夏玉米产量和土壤氨挥发的影响。通过田间土壤温度、水分、产量和土壤氨挥发累积量试验数据的验证,DNDC模型可以很好地模拟未来气候条件下不同处理的作物产量和土壤氨挥发累积量。【结果】模拟和实测结果均表明,在当前气候条件下秸秆还田会提高作物产量并促进土壤氨挥发,稳定性氮肥与普通尿素相比对产量无显著影响但会显著减少土壤氨挥发累积量。敏感性分析表明,作物产量与土壤氨挥发累积量均对施氮量最敏感。在RCP4.5排放情景下,单施稳定性氮肥（NF1）和单施尿素（NF2）分别在2050s—2090s和2070s—2090s产量显著降低,秸秆配施稳定性氮肥（SF1）和秸秆配施尿素（SF2）均在2050s—2090s产量显著升高;在RCP8.5排放情景下,单施稳定性氮肥（NF1）在2070s—2090s产量显著降低,单施尿素（NF2）产...     

不同灌溉施肥方式对马铃薯产量及土壤盐分迁移的影响

[目的]研究不同灌溉方式、施肥方式对马铃薯产量及耕层土壤水溶性盐迁移的影响。[方法]通过田间试验和土壤检测,分析水溶性盐分在土壤中的移动规律。[结果]漫灌处理,4层土壤总水溶性盐总量从上到下依次递增,各层土壤水溶性盐量漫灌施肥处理均高于漫灌不施肥处理;滴灌的2个处理,0~60 cm水溶性盐总量从上到下依次递增,60~100 cm明显降低;土壤各层水溶性盐总量滴灌基施均高于滴灌追施;0~100 cm土层水溶性盐量滴灌基施高于漫灌基施。[结论]不同灌溉施肥方式以滴灌+追肥效益最高;漫灌土壤盐分从上向下淋溶明显,滴灌土壤盐分淋溶不充分,盐分在20~60 cm有积聚作用;同等条件下,施肥量越高土壤盐分残留量越大,土壤次生盐渍化与施肥量关系密切。     

作物生长条件下沙拉塔纳农田水盐耦合运移模型

通过克州沙拉塔纳农田试验区实测资料的分析,建立了作物生长条件下土壤水分和盐分运移模型.在室内进行了土壤水分特征曲线,确定了扰动粘质粉壤土土壤水分特征曲线;再用HYDRUS模型反演计算了在室内外难以确定的土壤水分传导度,并用Van Genuchten方程拟合了参数.以这些参数为基础,模拟计算了气象条件类似土壤相同的格达良灌区土壤水盐运动规律,得出小麦作物从苗期至成熟期土壤含盐浓度随时间分布状况,为研究节水灌溉改良盐碱地课题提供科学数据.     

中国主要农作物生物质能生态潜力及时空分析

【目的】农业生物质能资源可开发潜力的估算是农业生物质能科学开发利用研究的关键和基础。同时农作物秸秆还田具有维护和增强土壤功能的作用,因此对农业生物质能生态潜力的评估,是实现农业生物质能可持续开发的重要前提。基于此,考虑土壤生态要求,研究不同还田比情景下中国主要农作物的生物质能生态潜力,并对其时空间特性和结构构成进行分析,为中国农业生物质能的开发利用提供参考。【方法】首先,结合相关历史统计数据,运用线性回归法、文献调研和专家预测等方法,对未来全国农作物播种面积、各省（市、自治区）播种面积占比、主要农作物种植比例和单产进行预测;其次,在分析已有相关研究的基础上,对秸秆的草谷比、工业比、饲料比和燃烧比进行设计,并从保护土壤功能的角度,结合相关研究文献,运用情景分析法,设计高、中、低三种秸秆还田比情景;最终,从空间分布和时间分布的角度,对中国主要农作物最终可利用生物质能潜力进行分析说明,并提出相关发展建议。【结果】（1）到2050年,低还田比（0.3）、中还田比（0.5）和高还田比（0.75）情景下中国主要农作物最终可利用生物质能分别为1.62亿吨标煤、0.78亿吨标煤、0.11亿吨标煤,且随着时间的推移,中国主要农作物最终可利用生物质能会发生空间、时间和种类构成集聚的现象;（2）在低、中还田比情景下,中国主要农作物最终可利用生物质能主要分布在东北、华东、华中,其中河南、黑龙江、山东、新疆等地占比较大;从时间分布上来看主要集中在8月、9月和10月,从构成上来看主要是由稻谷、小麦和玉米秸杆构成;（3）在高还田比情景下,从空间上来看则主要集中在华东、华中、华南和西南,其中广西、云南、河南、黑龙江等地占比较大,时间上则集中在1月、2月、11月和12月,在构成上则仅由小麦、豆类、薯类和甘蔗构成。【结论】在主要农作物生物质能开发方面,可优先考虑河南、黑龙江、新疆、山东等地。在构建区域农作物秸秆集散基地、农业生物质能开发利用产业基地、大型秸秆直燃发电基地等大型综合农业生物质能开发项目,可优先考虑东北和华中区域。此外,可通过农作物种植结构调整、提高农业管理水平等措施,进一步提高西南、西北地区主要农作物最终可利用生物质能潜力。     

The Potential Contribution of Subsurface Drip Irrigation to Water-Saving Agriculture in the Western USA

Water shortages within the western USA are resulting in the adoption of water-saving agricultural practices within this region. Among the many possible methods for saving water in agriculture, the adoption of subsurface drip irrigation （SDI） provides a potential solution to the problem of low water use efficiency. Other advantages of SDI include reduced NO3 leaching compared to surface irrigation, higher yields, a dry soil surface for improved weed control, better crop health, and harvest flexibility for many specialty crops. The use of SDI also allows the virtual elimination of crop water stress, the ability to apply water and nutrients to the most active part of the root zone, protection of drip lines from damage due to cultivation and tillage, and the ability to irrigate with wastewater while preventing human contact. Yet, SDI is used only on a minority of cropland in the arid western USA. Reasons for the limited adoption of SDI include the high initial capital investment required, the need for intensive management, and the urbanization that is rapidly consuming farmland in parts of the western USA. The contributions of SDI to increasing yield, quality, and water use efficiency have been demonstrated. The two major barriers to SDI sustainability in arid regions are economics （i.e., paying for the SDI system）, including the high cost of installation; and salt accumulation, which requires periodic leaching, specialized tillage methods, or transplanting of seedlings rather than direct-seeding. We will review advances in irrigation management with SDI.     

A simulation model assisted study on water and nitrogen dynamics and their effects on crop performance in the wheat-maize system: (II) model calibration, evaluation and simulated experimentation

The test on the model with data collected from two years’ field experiments revealed an ability to satisfactorily simulate crop parameters such as LAI, biomass accumulation and partitioning, yield, and variables influencing crop growth and development as nitrogen uptake by crops and partitioning in different organs, and dynamics of soil water and nitrogen including infiltration and leaching. With the model, crop yield, water use efficiency (WUE), nitrogen use efficiency (NYE) and water-nitrogen leaching at specific soil layers under various water and nitrogen management practices were simulated to provide data used as references for designing sustainable nitrogen and water management practices. The outputs of the simulated experiment with various treatments of irrigation and nitrogen application indicated that crop yield was closely related to water and nitrogen application, crop water use was positively related to irrigation amount, and nitrogen fertilization could improve the crop water use and WUE within certain limits. This is a valuable evidence to be considered in water-saving farming. Nitrogen uptake had a positive relation to nitrogen application, while irrigation to some extent improved its uptake by crops and hence increased NYE. Additionally, irrigation and fertilization had great effects on nitrogen leaching. Thus, in order to improve WUE and NYE, the model showed how nitrogen application and irrigation should be well coordinated.     

黑土培肥效果的定位研究——Ⅱ 土壤养分的变化

不同培肥措施对土壤全氮、全磷、碱解氮、速效磷的积累为:有机肥>秸秆还田>草木樨还田>化肥>对照;速效钾的累积增长为秸秆还田居首位,有机肥次之,对照区呈下降趋势。有机物料的培肥效果优于化肥。     

冀南地区蔬菜保护地土壤盐分积累特征

[目的]探究冀南地区蔬菜保护地土壤盐分的积累特征。[方法]以冀南地区永年县蔬菜种植区保护地和相邻露地粮田土壤为供试土壤,研究其土壤盐分积累现状和变化趋势。[结果]保护地土壤盐分含量均显著高于露地粮田土壤,且伴随种植年限呈增加的趋势;在垂直剖面上,盐分积累以0～20cm表层最为显著,随深度加深积累幅度减少;保护地与露地粮田相比,除HCO3-的含量随种植年限减少外,其他离子均有不同程度的积累,以NO3-和Ca2+的积累幅度最大。[结论]该研究为合理施肥管理和保护地土壤持续利用提供了理论依据。     

Precision Agriculture and Sustainability

Precision Agriculture (PA) can help in managing crop production inputs in an environmentally friendly way. By using site-specific knowledge, PA can target rates of fertilizer, seed and chemicals for soil and other conditions. PA substitutes information and knowledge for physical inputs. A literature review indicates PA can contribute in many ways to long-term sustainability of production agriculture, confirming the intuitive idea that PA should reduce environmental loading by applying fertilizers and pesticides only where they are needed, and when they are needed. Precision agriculture benefits to the environment come from more targeted use of inputs that reduce losses from excess applications and from reduction of losses due to nutrient imbalances, weed escapes, insect damage, etc. Other benefits include a reduction in pesticide resistance development. One limitation of the papers reviewed is that only a few actually measured directly environmental indices, such as leaching with the use of soil sensors. Most of them estimated indirectly the environmental benefits by measuring the reduced chemical loading. Results from an on-farm trial in Argentina provide an example of how site-specific information and variable rate application could be used in maintaining profitability while reducing N applications. Results of the sensitivity analysis show that PA is a modestly more profitable alternative than whole field management, for a wide range of restrictions on N application levels. These restrictions might be government regulations or the landowner's understanding of environmental stewardship. In the example, variable rate of N maintains farm profitability even when nitrogen is restricted to less than half of the recommended uniform rate.     

家庭农场测土配方施肥技术采纳行为及收入效应研究

测土配方施肥技术不仅有利于减少化肥的施用,还有利于控制农业面源污染,促进农民节支增收,是实现农业可持续发展的重要方式。基于理性小农理论,利用东北地区种植型家庭农场调查数据,运用内生转换模型,分析影响家庭农场采纳测土配方施肥技术的行为因素,探究测土配方施肥技术对家庭农场农业收入效应的影响。结果表明,东北地区家庭农场测土配方施肥技术采纳率仅为44.62%,采纳率偏低。年龄对该技术采纳呈现负向影响,受教育程度、农业技术培训、风险偏好、经营规模、土地流转期限和示范农场显著正向影响家庭农场对该技术的选择;受教育程度越高、接受过农业技术培训、风险偏好和示范农场对采纳该技术的家庭农场增收效果显著,经营规模大的家庭农场其采纳测土配方施肥技术收入提升效果最好。研究表明,测土配方施肥技术具有明显正向收入效应,能够显著提高家庭农场农业收入。因此,提出加快健全测土配方施肥技术推广机制,提升家庭农场主的人力资本水平,逐步改善测土配方施肥技术应用的约束条件,完善风险补偿机制,提倡家庭农场适度规模经营等政策建议。     

不同灌溉方式和作物类型对西北干旱区耕地土壤盐渍化的影响

土壤盐渍化是西北干旱区耕地发展的主要限制因素之一。近10年来,新疆石河子垦区耕地的灌溉方式和作物类型都发生了很大的变化,并对耕地土壤的盐渍化产生了影响。为此,基于不同作物类型、不同灌溉方式下典型耕地地块的实验数据,采用配对T检验、曼-惠特尼U检验等统计分析方法,研究了垦区灌溉方式和作物类型对耕层土壤盐分的影响。结果表明:(1)漫灌相对于滴灌来说,会降低土壤耕层的总含盐量,但是却使得耕层表层盐分积聚;漫灌条件下盐分在水平方向分布比较均匀,而滴灌条件下其分布离散程度较高。(2)作物类型对土壤耕层总含盐量及盐分在耕层土壤中的水平和垂直分布影响均不显著,短期的作物改种(棉地改为玉米地)对土壤耕层盐分含量没有明显影响。     

Impact of introducing a herb pasture area into a New Zealand sheep and beef hill country farm system: a modeling analysis

New Zealand is well known for export of meat and dairy products from low cost pastoral systems. These farm systems are continually evolving for increased efficiency, in part through the use of metabolic energy modeling tools by farmers and farm consultants to explore alternative farm system configurations and identify new efficiencies. One recent innovation is the introduction of a herb pasture area, such as plantain. We used metabolic energy modeling to quantify seasonal feed flows in two successive years in a New Zealand hill country farm system, and to analyze the impact of the introduction of an area of plantain. Models employed were a self-built Microsoft Excel spreadsheet and a commercial New Zealand farm systems modeling package, FARMAX. Herbage production, animal performance and financial results for a base farm scenario created from the average of survey data for hill farms in the southern North Island, and the same farm with 10% and 20% of the area in plantain for the years 2010–2011 and 2011–2012 were modeled. The self-built model performed similarly to the commercial model. The system configuration of the base farm stockpiles surplus autumn feed for release to animals in winter and also incorporates flexibility that confers resilience to interannual weather variation through varying dates animals are purchased or sold. The introduction of an area of plantain was predicted to increase herbage production, animal performance and financial returns. The predicted benefit was higher for the year 2010–2011 where a drought occurred in summer than for the following year with higher summer rainfall. This demonstrates the profitability of introducing a plantain area to New Zealand hill farm systems, and suggests plantain will assist to mitigate adverse effects of warmer and drier summer conditions associated with current climate change trends.     

脱硫石膏配合淋洗改良碱化土壤对土壤盐分分布及作物生长的影响

我国耕地盐碱化面积约占总耕地面积的7%,碱化土壤严重威胁了我国的农业发展和粮食安全;脱硫石膏是一种经济环保的碱化土壤改良剂,淋洗可以促进脱硫石膏改良碱化土壤过程中上层土壤脱盐。针对脱硫石膏改良碱化土壤对土壤盐分分布及作物生长的影响问题,在河套灌区采用田间试验的方法,对不同脱硫石膏用量(10.1、14.5和0t/hm2)配合不同淋洗量(1.52×103、2.20×103和0t/hm2)改良处理下土壤0~100cm土层的土壤化学指标(碱化度ESP、酸碱度pH和电导率EC)变化规律及2012年食葵的生长特性指标进行研究。结果表明:1)所有处理0~40cm土层ESP、pH和EC在第一年淋洗和秋浇后显著降低,之后逐渐趋向稳定,ESP和EC在年内有增加趋势;40~100cm土层各指标较0~40cm稳定,综合改良处理土壤ESP、pH略有降低,仅淋洗处理有升高的趋势;2)0~60cm土层综合改良处理改良效果优于其他处理,当深度大于60cm时,所有处理的改良效果不明显;3)高脱硫石膏配合淋洗对食葵的生长指标和产量的提高程度优于其他处理。脱硫石膏配合淋洗改良能够有效地改善碱化土壤盐分分布及作物生长情况,可为碱化土壤的改良提供借鉴。     

作物生长模型（CropGrow）研究进展

农业信息技术是基于信息技术与农业科学的交叉融合而形成的新兴技术,催生了数字农业和智慧农业的快速发展。作物生长模型作为其核心内容之一,可以动态模拟作物生长发育过程及其与气候因子、土壤特性和管理技术之间的关系,从而有效克服传统农业生产管理研究中较强的时空局限性,为不同条件下的作物生产力预测预警与效应评估等提供量化工具。本文重点介绍笔者团队在作物生长模型的构建与应用方面形成的总体技术方法、最新研究进展及未来发展思考。通过20多年系统深入的探索和实践,本团队以小麦、水稻等作物为主要对象,以“生理机制解析-模型算法构建-生产力动态预测-效应定量评估-模拟平台研发”为主线,综合运用系统分析、动态建模、虚拟现实、情景模拟及决策支持等方法,开展了作物生长模型CropGrow的构建与应用研究。首先,利用系统分析方法与动态建模技术,构建了机理性与预测性兼备的综合性作物生长模型（CropGrow）,包括阶段发育与物候期、器官发生与建成、光合生产与物质积累、同化物分配与产量品质形成、养分动态、水分平衡以及作物三维形态建成与虚拟显示等子模型,可数字化、可视化表征不同条件下作物生长发育与生产力形成过程;然后,结合地理信息系统（GIS）和遥感（RS）技术,构建了基于模型、GIS和RS有效耦合的区域作物生产力预测技术;进一步量化了气候变化、品种更新、土壤改良、措施优化对区域作物生产力形成的影响,拓展了适宜方案生成、理想品种设计、气候效应评估、耕地利用评价以及农业政策制定等应用技术;最后,运用构件化程序设计思想,基于作物生产数据库、作物模型构件库等,集成开发了基于模型的数字化、可视化作物生长模拟系统与决策支持平台,实现了数据管理、参数优化、生长模拟、遥感耦合、区域预测、方案设计、效应评估、安全预警、产品发布等综合功能。未来作物模拟研究将在完善基础数据库的基础上,进一步提升预测能力、量化基因效应、拓展智能决策、耦合多功能模型等,为粮食生产的预测预警、情景效应的量化评估、生产管理的智能决策、作物品种的优化设计等提供数字化支撑,对于保障国家粮食安全和推进数字农业发展具有重要意义。     

中国粮食作物家庭农场适度规模的比较研究

推进家庭农场适度规模经营是发展现代农业、建设社会主义新农村的必然趋势。选取粮食作物家庭农场为研究对象,对我国粮食作物家庭农场适度规模相关文献进行归纳与总结,主要针对粮食作物家庭农场的适度规模进行了比较,提出需确保粮食作物家庭收入达到当地城镇居民收入水平;种植水稻家庭农场的适度规模,应该约为10 hm~2,小麦的适度规模约为30 hm~2,无法达到规模的地区,应考虑种养结合、或者不同农作物的轮作和套种来实现适度规模经营;地理位置较偏远的山区,可考虑发展种植经济作物的家庭农场和农业合作社,利用合作社的优势为家庭农场的发展提供产业链服务,以期为我国的农业生产实践提供指导建议。     

干旱区绿洲农用地估价研究——以吐鲁番市为例

在吐鲁番市农用地估价课题研究的实践基础上,以马克思主义的地租、地价理论和西方经济学的收益理论为指导,以农用地估价为研究对象,坚持理论与实践相结合,选取收益还原法作为现阶段农用地估价的基本方法,并对估价成果的具体应用以及应用中应注意的问题提出了建议。     

Impact of cash crop cultivation on household income and migration decisions: Evidence from low-income regions in China

This study examines the impact of cash crop cultivation on household income and migration decisions, using survey data collected from low-income regions in China. Given farmers decide themselves whether to cultivate cash crops, an endogenous treatment regression model that accounts for potential selection bias issue is used to analyze the data. The empirical results show that cash crop cultivation exerts a positive and statistically significant impact on household income, but it does not affect household migration decisions significantly. The disaggregated analyses reveal that cash crop cultivation significantly increases farm income but decreases off-farm income.     

轮作不同高粱品种阻控设施菜田氮素损失潜力研究

为缓解华北地区设施菜田夏季休闲期氮素淋洗损失严重等问题, 提高氮素利用率及土壤生物多样性, 结合高粱的生物学特征, 选取晋杂12等6种北方常见高粱品种为供试品种, 以常规填闲作物甜玉米为对照, 筛选适宜作为北京设施菜田夏季填闲作物的高粱品种。结果表明, 从生物量、根系及养分带走量等方面来看, 晋杂12较其他品种均占优势, 成熟期生物量为11.2 t·hm^-2, 0~45 cm总根长为299 m, 作物地上部氮素带走量为139 kg N·hm^-2, 均显著高于常规填闲作物甜玉米, 可以替代甜玉米推广使用。同时研究发现冀梁2号品种在尿素施用后土壤铵态氮含量明显高于其他品种, 可能是作物根系分泌的生物硝化抑制剂减缓了硝化过程。与甜玉米相比, 高粱可能通过释放生物硝化抑制剂和根系在土壤剖面生物提氮共同起到减少氮素损失的作用。