Influence of tractor wheel tracks and crusts/seals on runoff: Observations and simulations with the RZWQM

In simulations on the fate of agricultural chemicals applied to crops, accurate partitioning of rainfall between infiltration and runoff is fundamental to chemical runoff predictions. We evaluated the Root Zone Water Quality Model (RZWQM version 3.1) against measured runoff from two field plots (15×45 m with 3% slope) on a Tifton loamy sand (fine-loamy, siliceous, thermic Plinthic Kandiudult). Six simulated rainfall events, each 25 mm h⁻¹ for 2 h, were applied to maize (Zea mays, L.) each year. In the uncalibrated mode, RZWQM under-predicted runoff by 40% on average, with the closest fit for events that occurred after full canopy. Saturated hydraulic conductivity (Ks) accounted for the majority of the uncertainty in predicted runoff. When Ks of the surface crust was back calibrated from the measured runoff, RZWQM predicted runoff closely for the remaining plots and events. Alternatively, using different Ks values for wheel track and crop beds, running the model for each and, then, proportionally assigning runoff also led to predictions that agreed with measured runoff. When spatial and temporal changes in Ks were calibrated to specific conditions at the site, RZWQM effectively predicted runoff.     

农用拖拉机如何在复杂道路上行驶

农用拖拉机大多在农村或城市郊区行驶,道路曲折、高低不平、多为田间土路。由于土质和含水量的不同,有的松软、有的坚硬、有的粘着,田间地头有沟、渠、堤,路经的村庄、集市、桥梁、涵洞坡坎较多,这与汽车的行驶道路相比复杂多了,而且多以组合机组情况行驶,不是挂带、悬挂农具,就是拖带挂车。因此,行驶中安全尤为重要,要求拖拉机驾驶员技术要熟练,精力要集中,能在各种复杂的道路条件下安全行驶。     

东方红中轮拖制动器压盘铸件工艺的改进

<正>东方红-E300,304,350,400型轮式拖拉机制动器压盘（材质QT500-7）的铸件过去均采用顶注压边冒口工艺生产,但这种工艺容易使铸件出现夹渣、砂孔、缩孔从而导致铸件报废。在对零件结构和顶注工艺进一步分析并经过多次试验后,采用了中注、顶冒口加集渣包的新工艺,效果良好,介绍如下。1 铸件结构与顶注工艺分析制动器压盘铸件结构与顶注工艺分别见图1、图2。     

砾石覆盖对抑制旱作农田土壤风蚀效果的风洞模拟

针对中国阴山北麓旱作农田风蚀比较严重的现实,将旱作农田地表铺设不同覆盖度和粒径的砾石后进行风洞试验,旨在探索砾石覆盖度和粒径在抑制旱作农田土壤风蚀效果方面的作用,为采取合理的防风蚀措施提供技术依据。利用野外风洞原位测试方法,完成了6种风速下对应净风和挟沙风时的不同砾石粒径和覆盖度下的旱作农田土壤风蚀测试。结果表明：无论净风还是挟沙风,增加砾石覆盖度,旱作农田抗风蚀效率均提高,但当砾石覆盖度超过28%后,其对提升抗风蚀效率作用不大;在相同覆盖度下,随砾石粒径的增加,输沙量、抗风蚀效率略有变化,但不明显;将耕     

Cage wheel blocking in wet clay soil

Experiments to investigate how blocking in cage wheels occurs showed three possible mechanisms. It was found that these mechanisms were strong functions of lug slip and lug spacing (the angular spacing between two consecutive lugs), in Bangkok clay soil at 49% (d.b.) moisture content. The blocking process observed at 100% slip was found to be the most likely mechanism by which cage wheels block in wet soil in practice.     

The intertemporal impact of soil erosion on non-uniform soil profiles: A new direction in analyzing erosion impacts

Soil erosion studies by economists have utilized relatively simple yield response functions compared to productivity simulation models used by soil scientists in order to endogenously solve for optimal management schemes. This paper combines the optimization techniques of previous economic studies with a more complex measure of soil productivity than simply soil depth which has been used previously. An illustrative model demonstrates how erosion affects different types of soil profiles found in the United States and isolates three different ways that erosion can impact productivity. Estimation procedures that do not account for the non-uniform nature of soil profiles can misstate the impact of soil erosion on cropland productivity. The framework, though perhaps overly simplified for direct use, disentangles the impacts of soil erosion into substitution, mixing and depth effects and suggests how varied profiles should be managed in different ways according to how each is impacted by erosion.     

工农-12手扶拖拉机驱动轮轴断裂原因及结构改进

在对工农-12手扶拖拉机驱动轮轴断裂原因进行分析的基础上,对驱动轮轴的结构进行了改进,从而改善了驱动轮轴的受力状况,消除了拖拉机运输过程中由于驱动轮轴断裂而引发的安全隐患。     

冬小麦根系对土壤抗侵蚀能力的影响

土壤的抗侵蚀能力包括土壤的抗冲性和抗蚀性。根系的固结缠绕对土壤的抗侵蚀能力具有显著的影响。以不同含量的冬小麦根系的土样为研究对象,采用静水崩解法和抗冲槽法测定其抗冲性和抗蚀性。结果表明：根系能够降低土壤的崩解速率,即随着根系含量的增加,土壤崩解率缓慢降低。研究结果显示：土壤崩解过程可以分为吸水崩解阶段、快速崩解阶段、稳定崩解阶段3个阶段,随根密度增加,根系作用延长了土壤吸水崩解和快速崩解阶段,降低了土壤崩解速度。土壤抗冲刷系数随着根重密度的增加呈递增的二次函数关系。     

中国保护性耕作对土壤风蚀的影响研究

为探讨保护性耕作措施对农田土壤风蚀的影响,通过中国知网,以“免耕或保护性耕作并且土壤风蚀”为主题,检索至2020年底公开发表的中文期刊论文,对检索到的论文进行整理分析。结果表明,中国保护性耕作对土壤风蚀的田间试验均来自北方干旱半干旱农田,研究方法以集沙仪野外测量为主；保护性耕作研究中对土壤风蚀方面的研究占比较少,产量效应一直是保护性耕作的研究重点；综合相关研究分析,保护性耕作平均可减少农田土壤风蚀量71.2%；保护性耕作减少农田土壤风蚀具有普遍性,少量研究认为保护性耕作不能减少农田土壤风蚀量。     

沂蒙山区土壤侵蚀垂直景观格局的分形特征

以北方土石山区的典型代表沂蒙山区为研究区,以TM影像和地形图为源数据,根据全国土壤侵蚀分类分级标准,综合运用GIS和RS技术,获取以50 m为带宽的土壤侵蚀强度垂直分带数据。在Fragstats3.3中提取周长面积分维数（D）,计算稳定性指数（SI）,旨在揭示沂蒙山区土壤侵蚀分形的垂直变化特征。结果表明,土壤侵蚀景观在垂直维度上具有明显的分异性。在景观水平上,土壤侵蚀景观周长面积分维数（D）随高程呈先迅速增大后缓慢增大趋势,稳定性指数（SI）则呈先急剧减小后缓慢减小趋势。在缀块类型水平上,对于研究区,D值     

电子及信息技术在拖拉机中的应用

20世纪90年代以来，电子及信息技术的迅速发展埘所有传统产业和产业技术发展的影响都是广泛而深刻的。就农业拖拉机产品的一般情况而言，已经受益于电子及信息技术的应用而获得重大科技进步的领域就有：动力换挡系统、前驱动桥控制、前后桥差速锁、前后动力输出轴和离合器、液压悬挂系、农具辅助操作系统等；正在     

华亭县土石山区水土流失控制技术与效益研究

华亭县土石山区属黄河流域多沙粗沙区,该区生态环境脆弱,水土流失严重,在该区开展小流域水土流失控制技术与效益研究,对促进黄土高原小流域生态建设有重要意义。该文采用统计分析的方法,通过对七条典型小流域的泥沙来源、土壤侵蚀量和治理措施分布的时空顺序的分析研究,得出在治理模式不同,在治理程度相近的情况下,其水保效益差异显著。建立良好的生态环境是经济社会发展的基础,水土保持是土石山区生态环境建设和新农村建设的基础。     

EXCEL函数在拖拉机可靠性试验中的应用

可靠性试验是生产企业和鉴定部门的一项重要工作,可靠性试验后期的试验数据整理非常繁琐,而试验数据的整理是整个试验中比较重要的一部分.在高效率办公的环境下如何更简单快捷的完成工作而又不能影响整个试验的过程及试验数据的科学公正,是拖拉机可靠性试验工作者面临的一个重要问题.在试验数据整理上应用现代化的办公手段不但可以节省时间还可以提高工作效率.使用Excel函数就可以帮助达到目的.     

拖拉机电气系统的故障原因及诊断方法

拖拉机电气系统的故障,无论是发生在线路上,还是发生在电器设备上,一般都是由短路或断路原因引起,其现象与诊断方法如下：     

小流域土壤侵蚀动态过程模拟模型

建立流域土壤水蚀预报模型将为小流域综合治理、土地利用规划等宏观决策提供依据,为小流域水土保持效果有效评价提供参考。通过对小流域侵蚀动态过程的分析,在水流连续方程、动量守恒方程及泥沙质量守恒方程基础上,对坡面－沟道及各沟道间土壤侵蚀时空关系进行合理耦合,建立了流域系统土壤侵蚀动态模拟过程模型;采用有限元方法对土壤侵蚀模拟模型进行数值离散,建立了小流域系统数值离散模型;在确定流域时空离散方法基础上,采用VC++语言编制流域水蚀模拟程序;在室内人工模拟降雨条件下,对模型小流域50 mm/h降雨强度,5 min降雨历时情况下土壤侵蚀情况进行模拟,在得到流域内典型点处径流流量、径流含沙量及各沟道流速动态过程的同时,将流域内各沟道出口处模拟结果与测量结果比较,径流流量、径流含沙量、流速模拟精度均高于80%。研究结果表明小流域土壤侵蚀模拟模型的建立是可靠的,模型的数值离散方法及编制的计算程序是完全可行的。这一模型的建立将为小流域土壤侵蚀动态过程的模拟预报及实现由小流域向中大流域的侵蚀动态模拟预报提供一定的理论基础。     

机车传动系统的故障特点

机车的传动系统主要由离合器、万向节、变速箱和后桥等部分组成。该系统常见的故障有:离合器不能分离,分离不彻底或打滑,变速箱挂挡困难或乱挡、跳挡,传动副过热或发出异常响声,漏油等。现将传动系故障的特点叙述如下: 一、离合器、变速箱操作不当是传动系产生故障的一个重要原因     

2021年拖拉机行业机遇与风险并存

拖拉机产业是一个国家农机产业的支柱,很大程度上说拖拉机强民族农机工业才能强.农机购置补贴系统10年数据显示,国内拖拉机行业年产值约300～350亿元,是国内第一大农机品类,2020年拖拉机整机企业超过200家,零部件企业预计有上万家,直接和间接从业者有上百万,用举足轻重来形容一点都不为过;另一方面拖拉机是很多农机具的动...     

农用三轮摩托车转向盘减振研究

针对一种农用三轮摩托车转向盘振动严重的现状,通过试验模态分析和有限元计算分析,将两者所得结果进行比较,分析了结构不合理的原因、提出多种改进方案优化其结构,并通过试验进行验证。试验证明优选的转向盘达到了理想的减振效果。     

Systematic design and evaluation of crop rotations enhancing soil conservation, soil fertility and farm income: a case study for vegetable farms in South Uruguay

Rapid changes in the social and economic environment in which agriculture is developing, together with the deterioration of the natural resource base threatens sustainability of farm systems in many areas of the world. For vegetable farms in South Uruguay, survival in the long term depends upon the development of production systems able to reduce soil erosion, maintain or improve physical and biological soil fertility, and increase farmer’s income to socially acceptable levels. We propose a model-based explorative land use study to support the re-orientation of vegetable production systems in South Uruguay. In this paper we present a new method to quantitatively integrate agricultural, environmental and socio-economic aspects of agricultural land use based on explicit design objectives. We describe the method followed to design and evaluate a wide variety of land use activities for Canelón Grande (South Uruguay) and we illustrate the usefulness of this approach in an ex-ante evaluation of new farming systems using data from 25 farms in this region. Land use activities resulted from systematic combination of crops and inter-crop activities into crop rotations, different crop management techniques (i.e., mechanisation, irrigation and crop protection) and animal production. We identified and quantified all possible rotations and estimated inputs and outputs at crop rotation scale, explicitly considering interactions among crops. Relevant inputs and outputs (i.e., soil erosion, balance of soil organic matter and nutrients, environmental impact of pesticides, labour and machinery requirements, and economic performance) of each land use activity were quantified using different quantitative methods and following the target-oriented approach. By applying the methodology presented in this paper we were able to design and evaluate 336,128 land use activities suitable for the different soil types in Canelón Grande and for farms with different availability of resources, i.e., land, labour, soil quality, capital and water for irrigation. After theoretical evaluation, a large subset of these land use activities showed promise for reducing soil erosion, maintaining soil organic matter content of the soil and increasing farmer’s income, allowing improvement of current farming systems in the region and providing a widely diverse set of strategic options for farmers in the region to choose from. This method can be used as a stand-alone tool to explore options at the field and farm scale or to generate input for optimisation models to explore options at the farm or regional scale.     

变型拖拉机主要技术参数研究

由手扶拖拉机变型而来的变型拖拉机 ,具有较好的动力性、制动性、操纵性和稳定性 ,运输速度也大大提高 ,因而在湖南省农村地区的应用日益广泛。本文分析了湖南省生产的变型拖拉机的结构和主要技术参数 ,讨论了动力配备、最小转向直径和载荷分配等问题 ,为变型拖拉机的合理设计提供了理论依据