A field estimate of SO2 deposition velocities to rapidly growing soybeans

Field-grown soybeans were exposed to elevated SO₂ levels in an open-air fumigation system which produced minimal alteration of the crop environment. The increase in S content of the fumigated plants as compared to unfumigated controls was used to estimate the deposition velocity of SO₂ to the crop. Estimates ranged from 0.5 to 0.9 cm s^?1, which is in the lower part of the range found by micrometeorological techniques, confirming that estimates based on short-term gradient measurements are realistic.     

A simple wet-only rainfall collector

Details of an inexpensive event-actuated sampler used in the Hunter Region (Australia) Acid Precipitation Project are described. The sampler is designed for non-freezing conditions and is labor rather than material intensive. Cost of parts is approximately $120 (Australian).     

A multi-site field evaluation of granular inoculants for legume nodulation

The most common method of inoculating legume crops in Australia is the application of peat slurry inoculant to seed. The recent introduction of granular (solid) formulations of inoculants into the Australian market has provided the potential to apply rhizobia with greater ease, but their efficacy has not been independently evaluated. Here, we compare the efficacy of a range of experimental and commercially-available granular inoculants on chickpea, faba bean, lentil, lupin and pea crops in comparison with un-inoculated treatments, and with conventional seed-applied peat slurry inoculants. Thirty-seven field experiments were established in Victoria, South Australia and southern New South Wales over five years. Peat slurry inoculants provided effective nodulation of all legumes. Granular inoculants varied markedly in their ability to improve grain legume nodulation. The size of response depended inversely on background nodulation from soil rhizobial populations. At sites with median background nodulation, peat granules and attapulgite clay granules placed with seed resulted in nodulation similar to peat-slurry-based inoculation, but treatments with bentonite clay granules did not increase nodule numbers much above those in un-inoculated treatments. The generally lower numbers of rhizobia g⁻¹ in the bentonite granules, translated to lower rhizobia application rate to the soil. However, differences in number of rhizobia g⁻¹ granule did not fully explain the nodulation differences between granules. Granule moisture content and granule particle size differed markedly between granule types but their influence on nodulation was not tested. Grain yields did not differ between attapulgite granules placed with seed, peat granules and peat slurry inoculants (all well-nodulated treatments), but were lower with bentonite granule inoculants. Yield differences within sites were related to nodulation and the differences between treatments attenuated as background nodulation increased. Overall, these studies demonstrate that certain granule types have the potential to be used in Australia with grain legumes, particularly in circumstances when seed-applied inoculants are problematic, such as where seed fungicides or insecticides need to be applied. However, granular inoculant formulations differ substantially in their potential to produce nodules on a range of grain legumes.     

干湿交替对黄土崩解速度的影响

耕作土壤在降雨、灌水之后,其由翻耕后的疏松状态逐渐变得较为紧实,土粒之间会重新结合,土壤结构得到重组。土壤抵抗侵蚀能力发生了一定变化。通过土盒模拟土壤干湿交替过程,研究耕作土壤干湿交替过程中土壤容重和静水崩解变化。采用Richards模型对土壤崩解过程进行了模拟,分析干湿交替对土壤崩解速度的影响,结果表明：随土壤干湿交替次数的增加,土壤容重增长缓慢,土壤的固结从快变慢。随干湿交替次数的增加,土壤的崩解速度逐渐降低。其崩解过程可划分为缓慢崩解阶段、指数崩解阶段和崩解完成阶段。随干湿交替次数的增加,缓慢崩解阶段延长,指数崩解阶段推迟出现。经3次干湿交替后,土壤崩解速度显著降低,土壤抗蚀性增强。     

网链式花生地残膜回收机设计与试验

针对现有花生地残膜回收设备存在的漏膜、回膜、缠膜等问题,设计一种网链式花生地残膜回收机,主要工作部件包括挖掘铲、升运网链、碎土辊、双作用激振装置、集膜装置等,可一次性完成挖掘起膜、输膜、清土和集膜作业.根据升运网链的结构特性,建立其残膜支撑度与土壤通过性的数学模型,通过分析计算验证了网链结构用于残膜输送的优势;设计了可自由浮动的碎土辊,并对其工作压力进行力学分析,得出其结构参数;运用ADAMS软件对双作用激振装置进行仿真,确定其结构尺寸与振动幅度为25mm;开发了升运角可调的二级升运网链,在完成残膜输送的同时可使黏性土块沿网链滚落,对二级升运网链的有效分离长度和升运角调节范围进行了设计;为实现高效卸膜,设计了液压驱动的集膜装置,并对液压缸参数进行了计算校核.田间试验结果表明,当机具前行速度1.0m/s、挖掘深度100mm、一级升运网链线速度2.0m/s、二级升运网链线速度2.2m/s、双作用激振装置频率10Hz时,收膜率为91.5%,含土率为17.2%,能够满足花生地残膜回收需求.研究方法与结果可为相关装备研发提供参考.     

湿干循环下膨胀土渠道边坡的破坏模式及稳定性

针对北疆地区膨胀土渠道因季节性通水导致的边坡失稳破坏问题,通过建立简化地质条件的离心模型试验,得到了湿干循环下膨胀土渠道边坡的变形及破坏特征,提出了由渠道通水、停水引起的湿干循环下膨胀土渠道边坡的破坏模式;在此基础上,利用GeoStudio软件分析了不同裂隙分布形式对膨胀土渠道边坡渗流特性及稳定性的影响。结果表明:运行过程中渠基膨胀土开裂是引起渠道边坡发生浅层失稳破坏的决定性因素;渠道因季节性通水造成的湿干循环作用下膨胀土渠道边坡破坏模式主要由“子土块”剥落破坏及“后缘张拉裂隙的扩展”2种破坏相互混合叠加构成。对比数值模型中不同后缘裂隙深度下渠坡的安全系数可知,当裂隙贯穿区深度为0.5 m时(工况1),对应的安全系数下降幅度约为60%,但此时的安全系数仍较大,渠坡可视为稳定;而当裂隙贯穿区深度继续增加至1 m时,渠道的安全系数下降幅度达到约74%,此刻的安全系数接近一级安全等级阈值(1.25),渠坡虽仍为稳定,但已经具备了失稳的可能。边坡的浅层破坏主要由“子土块”剥落模式决定,而后缘张拉裂隙的扩展对渠坡的失稳起到促进作用。此外,数值模拟结果还显示裂隙的存在加剧了坡面表层土体的孔压波动,易造成表层“子土块”的剥落。研究成果为进一步揭示季节性通水诱发的膨胀土渠道灾变提供了参考依据。     

氯盐侵蚀和干湿循环条件下浮石混凝土的耐久性

为了探究干湿循环条件下氯离子对浮石混凝土的侵蚀机制,借助核磁共振测试技术,分析浮石混凝土在干湿循环条件下微观孔隙结构特征,对侵蚀后的浮石混凝土内部微观结构进行X射线衍射物相分析与电镜扫描分析,进而探讨浮石混凝土抗氯离子侵蚀性能。研究结果表明,在氯盐侵蚀作用下,浮石混凝土和普通混凝土的质量损失变化率与相对动弹性模量变化趋势相一致;发现浮石混凝土谱面积是普通混凝土谱面积的1.0～1.7倍;浮石混凝土侵蚀破坏主要为内部发育新的小孔隙和中小孔隙向大孔隙和裂纹发育造成的,普通混凝土侵蚀破坏主要为内部的微小孔隙和小孔隙向大孔隙和裂纹发育造成的;浮石混凝土(0.1～1.0 μm孔隙所占比重较多,普通混凝土(0.01～0.1 μm孔隙所占比重较多;干湿循环120次后浮石混凝土孔隙度增加26.7%,自由流体饱和度减少1.0%,干湿循环120次后普通混凝土孔隙度增加77.8%,束缚流体饱和度减少7.3%;氯盐侵蚀后均生成以Friedel盐为代表的多种腐蚀结晶物。该研究可为浮石混凝土在氯盐环境下农业水利建设提供理论依据。     

Urban wet deposition nitrate: A comparison to non-urban deposition

The concentration of nitrate in both wet and dry deposition has both increased historically and currently, and recently parallels emissions in NO_x. Since NO_x is produced in amounts comparable to SO₂, it is an important contributor to acid deposition, and is produced in higher amounts in urban areas due to concentrated sources. Prior to this study, national acid deposition monitoring networks in the United States have been and remain established in non-urban areas. This research study consisted of a comparison of precipitation sampling and analysis of wet deposition nitrate and pH for each deposition event in each of two urban sites over a 15 mo period. Also, a comparison of urban data and data generated at a nearby non-urban NADP site was made by examination of both monthly and seasonal data. This research suggests that national monitoring programs should consider inclusion of urban and non-urban monitoring sites in order to achieve a more representative regional assessment.     

黄土高原地区草场效益多目标评价

本文从整个黄土高原地区草场的现状与发展战略的角度,运用多目标优化方法,对黄土高原11类草场资源进行综合评价,为合理有效地利用天然草场,发展畜牧业提供科学依据。     

烟草田间作业机械评价模型的构建

为评价农业机械的适用性满意度,探索基于实际生产管理需要的农业机械选型方法。以烟草种植和烟草田间作业机械为研究对象,将烟草种植流程划分为3个阶段10个环节,并设定各环节的评价指标体系,每个环节设计了作业成本、作业效率、作业效果、使用效应等4个二级指标,共44个评价指标。结合田间实地测试采集评价指标数据;依据农艺要求量化评价指标的评判基准;采用层次分析法,构建综合评价模型。以起垄环节为例评价模型的应用,共涉及7台不同类型的起垄机组（编号分别为I,II,...VII）,其中,IV、V为"履带式",VII为"复合式",其余均为"手扶式"。测试过程表明,"手扶式"起垄机组工作状态易调整、作业效果好;"履带式"起垄机组整机质量较大,动力不足时容易导致作业、行进速度变缓;"复合式"起垄机组整机结构复杂,操作舒适性和安全性不高。从评价结果看,参与测试的7台起垄机组中,作业成本指标排序靠前是I、III、II号机组,评价值分别为0.91、0.89、0.85;作业效率指标排序靠前的是V、IV、II号机组,评价值分别为1、0.49、0.41;作业效果指标排序靠前的是II、V、I号机组,评价值分别为0.96、0.69、0.66;使用效应指标排序靠前的是I、II、V号机组,评价值分别为0.93、0.75、0.59;综合评价表现较佳的是II、I、V号机组,适用性满意度评分分别为0.75、0.68、0.66,选型评价结果与当地实际情况相吻合。该模型可为农业机械选型定量化的比较提供依据和参考。     

电场对作物种子影响有效性的综合评价方法

针对电场对作物生物效应的影响,利用数据包络分析的有关理论,给出了用于综合评价电场强度对作物生物效应影响的非参数方法和相应的数学模型,提出了用于生物效应-电场强度影响有效性分析的图形法和表格法,为探讨不同外部条件对作物综合生物效应的影响程度以及在不同电场强度下某一生理指标与综合生物效应之间的关系提供一种有效的分析工具.并应用该方法对不同电场强度对小麦种子幼苗形态指标株高、根长、鲜质量、干质量及生理生化指标POD、SOD、MDA的影响进行综合评价.结果表明:不同电场处理条件对小麦幼苗生长及生理生化过程产生不同影响,在0.5～6.0 kV/cm场强范围,随电场强度增加,生理指标呈振荡性变化,且2.5 kV/cm和4.0 kV/cm场强为最佳处理条件.     

Measuring dry deposition: A re-assessment of the state of the art

The exchange process known as dry deposition encompasses the dynamic exchange of trace gases and aerosol particles, and the gravitational settling of large particles. Except for particles large enough that their sedimentation velocity exceeds turbulent velocities, the rate of deposition is mostly determined by surface properties, such as roughness, stickiness, and wetness, and by atmospheric stability. Thus, it is difficult to interpret results obtained using collection devices having surfaces different from those of nature. Other methods for measuring dry deposition exist, mostly micrometeorological, but these are sufficiently complicated that routine application as in a monitoring network is not yet feasible. For some chemical species and in some locations, inferential methods offer considerable promise. These methods measure atmospheric concentrations (C) of the relevant chemical species, and derive relevant deposition velocities (v_d) on a site-specific, species-dependent, and time-evolving basis. The dry deposition rates of interest are then evaluated as the product v_d.C. A major goal of current research programs is to provide the knowledge necessary to evaluate v_d. Experimental methods are reviewed, and potential sources of error are examined, for both the research methods and the “concentration monitoring” methodologies presently being advocated for use in numerical models as well as for routine monitoring.     

基于田间数据的土壤肥力质量综合评价

摘要：采集了小清河济南样区土壤表层的104个样点数据,进行了土壤速效钾、土壤速效磷、土壤有机质、土壤碱解氮和土壤酸碱度含量等区域化变量的实验室测定,基于内梅罗指数进行了土壤肥力质量评价,综合运用统计方法,序贯高斯模拟和空间滞后模型进行了土壤肥力要素变量的空间建模和综合评判。内梅罗评判结果表明研究区田块具有中等的土壤肥力质量,土壤有机质含量与土壤肥力质量具有较强的相关性,是影响该区肥力质量的关键因子。土壤有机质、土壤速效磷和土壤酸碱度变量的空间诊断建模结果表明,变量之间基于最大似然法的空间滞后模型的估计精度优于基于最小二乘法的经典统计模型估计,序贯高斯2 000次土壤内梅罗指数模拟结果表明土壤肥力质量具有一定的梯度变化,并呈现出高值和低值明显的条带状的分布,总体上表现为由内向外肥力质量减小的趋势特点,该研究对小清河济南样区肥料的施用具有参考意义。     

太阳能平板型集热器阵列排布优化

为了优化集热器阵列排布便于水平屋顶有限空间的安装,该文建立了日均遮挡模型和太阳辐射模型。利用所建模型研究了集热器阵列排布长宽比与纬度、日均遮挡因子、阵列占地面积、到达集热阵列的太阳辐射量间的关系。结果表明,大型集热器阵列(占地面积≥500m2),冬至日日均遮挡因子随阵列长宽比和纬度的增加而增大。长宽比∈[1/10,3/1)时,日均遮挡因子上升较快;长宽比∈[3/1,10/1]时,日均遮挡因子增加平缓。对于占地面积∈[50,1000]m2的集热器阵列,面积越小、日均遮挡因子随长宽比的变化越快。冬半年各月水平面上日均太阳辐射分布情况对到达阵列的太阳辐射量最大对应的最佳长宽比存在较大影响。鉴于太阳辐射分布的影响以及便于工程应用,文中给出了中国不同纬度13个城市5种集热器阵列的最佳长宽比;研究结果可为太阳能集热阵列的排布优化提供参考。     

Attempt of a flux‐based evaluation of field capacity

Field capacity is one of the most frequently used soil parameters. According to the original definition, the field capacity is a site‐specific parameter, which is closely connected to soil water flux. Many of the existing procedures for field‐capacity estimation neglect its flux‐based character. In this study, a method and selected results are presented. This allows a better reflection of the unsteady behavior of unsaturated water flow in estimating field capacity. Based on the velocity of the relative internal drainage, a threshold value is defined (field‐capacity threshold) which enables a flux‐based estimation of the field‐capacity value. Furthermore, the direct consideration of the drainage time allows the soil water contents to be estimated for defined internal drainage durations.     

Correlation of soil tests with pot and field trials in the evaluation of soil fertility

The practical importance of soil tests in bringing about efficient use of fertilizers is well established. Extensive areas in India are producing Only a fraction of their yield potential due to the lack of enough plant nutrients whose need could be easily assessed by soil tests and suitable recommendations of fertilizer use to increase crop production could be given.     

稻田复种轮作模式的生态经济效益综合评价

为了筛选具有可持续性、适合鄱阳湖生态经济区的冬季绿色高效循环复合种植模式,通过2012年—2013年连续2年的田间定位试验,采用AHP法和综合指数法对鄱阳湖生态经济区5种稻田复种轮作模式(冬闲?稻?稻?冬闲?早稻?晚稻,绿肥?早稻?晚稻?油菜?玉米||大豆?晚稻,油菜?玉米||大豆?晚稻,蚕豆?早稻?甘薯||玉米?蔬菜?甘蔗||大豆,蔬菜?甘蔗||大豆?绿肥?早稻?晚稻)的生态经济效益进行了综合评价。结果表明:按照晚稻价格比折算后,两年间各种植模式中蔬菜?甘蔗||大豆种植模式的作物产量最高,其次是绿肥?早稻?晚稻,蚕豆?早稻?甘薯||玉米的作物产量最低。生态经济效益综合评价表明,2012年各系统的综合效益指数大小排序依次为:蔬菜?甘蔗||大豆油菜?玉米||大豆?晚稻蚕豆?早稻?甘薯||玉米绿肥?早稻?晚稻冬闲?早稻?晚稻,说明蔬菜?甘蔗||大豆种植模式"改稻为经",是能够带动稻田高产高效的种植模式,有利于农业生产的可持续发展。2013年经过稻田复种轮作后,各系统的综合效益指数表现为:绿肥?早稻?晚稻蔬菜?甘蔗||大豆油菜?玉米||大豆?晚稻蚕豆?早稻?甘薯||玉米冬闲?早稻?晚稻,表明稻田冬种紫云英模式的绿肥?早稻?晚稻种植模式能兼顾三大效益,有利于农业生产的可持续发展。从两年的综合效益结果来看,蔬菜?甘蔗|大豆→绿肥?早稻?晚稻模式能够带动稻田高产高效,能兼顾经济效益、生态效益和社会效益,可解决粮食安全和农业结构调整及农民增收等社会问题,而且对于冬季农业开发、自然资源的充分利用和农业生产的可持续发展也有极大的促进作用。综合来说,蔬菜?甘蔗||大豆→绿肥?早稻?晚稻模式是适合我国鄱阳湖生态经济区大面积推广应用的稻田冬季农业开发与复种轮作循环模式。     

利用反向射流提升无盖板型太阳能集热器性能

为了进一步提高无盖板型太阳能空气集热器的集热效率,该研究提出了一种利用U型管制造反向射流强化集热板换热的无盖板型太阳能空气集热器。通过试验研究了该型集热器内部的温度分布特性,以及2020年12月10日和2021年6月20日的集热性能。试验结果表明：反向冲击射流的冷却作用可以有效降低集热板表面温度,形成覆盖大部分集热板面积的低温区域,且温度分布较为均匀;作为产生反向射流的U型管,还可以充当肋片结构对进入集热腔内的空气进行预热,夏季晴朗工况下U型管的进出口温差可达3.5 ℃;该型集热器在6月20日的平均集热效率可达到80%,而12月10日的热效率仅为45%,冬夏集热效率的差别较大。该研究为无盖板型太阳能集热器性能优化提供了新思路。