油麦兼用型气送式集排器匀种涡轮设计与试验

针对油麦兼用型气送式免耕播种机宽幅播种时各行排量一致性受地表坡度变化影响的问题,设计了一种利用输送气流驱动转动、安装于分配装置的匀种涡轮,分析了匀种涡轮进口工作角和出口工作角对输送气流速度的影响,确定了影响3种匀种涡轮工作特性的关键参数。应用CFD仿真中的6自由度动网格模型及台架试验,对比分析3种匀种涡轮对输送气流分布及匀种涡轮转速的影响,结果表明：进口工作角和出口工作角均为锐角的匀种涡轮可提高种子的输送及搅拌性能。选择叶片数量为4、6、8、10的匀种涡轮进行了分配装置内流场分布仿真试验,结果表明,增加匀种涡轮叶片数量可提高匀种涡轮出口处输送气流分布的稳定及均匀性。利用智能种植机械测试平台模拟田间作业不同地表坡度时,安装不同数量叶片的匀种涡轮对各行排量一致性的影响,结果表明：转速为20～50 r/min,沿播种机作业方向的前后与侧向单向组合摆动、前后与侧向往复组合摆动角相对平整地表在-5°～5°变化,叶片数量为8时,油菜及小麦各行排量一致性变异系数最小,分别为4.99%～5.82%和3.85%～4.92%;前后与侧向单向组合摆动角绝对值为5°时,叶片数量为8的匀种涡轮比无匀种涡轮排种油菜和小麦时各行排量一致性变异系数分别降低7.53、11.98个百分点,满足地表坡度变化时油菜及小麦的排种要求。     

联合收割机割台地面仿形控制系统设计及试验

为了提高联合收割机自动化水平、降低劳动强度,研发了割台地面仿形控制系统,设计了割台地面仿形机构,采用角度传感器获取其随地面的浮动情况,并结合位移传感器检测割台油缸伸缩量,来推算得到割台高度信息,并进行了田间试验研究。试验结果表明:该系统结构简单,性能稳定,割台高度控制误差不大于12mm,满足联合收割机田间作业要求。     

我国玉米免耕播种机械化技术发展研究

介绍我国玉米免耕播种机械化技术发展现状,分析影响其推广应用的主要因素,并依此提出完善玉米作物育种系统、加强玉米免耕播种机的研制、建立和完善玉米免耕播种机械化技术体系等有效措施,以推动我国玉米免耕播种机械化技术的进一步发展。     

Time-variable soil hydraulic properties in near-surface soil water simulations for different tillage methods

Simulating near-surface soil water dynamics is challenging since this soil compartment is temporally highly dynamic as response to climate and crop growth. For accurate simulations the soil hydraulic properties have to be properly known. Although there is evidence that these properties are subject to temporal changes, they are set constant over time in most simulations studies. The objective of this study was to improve near-surface soil water simulations by accounting for time-variable hydraulic properties. Repeated tension infiltrometer measurements over two consecutive seasons were used to inversely estimate the hydraulic properties of a silt loam soil under different tillage - conventional (CT), reduced (RT), and no-tillage (NT). Simulated water dynamics with constant and time-variable hydraulic parameters were compared to observed data in terms of the soil water content and water storage in the near-surface soil profile (0-30 cm). The measurements indicate a considerable temporal variability in the saturated hydraulic conductivity, the field-saturated water content and the parameter α of the van Genuchten/Mualem model. Temporal variability was largest for CT and RT, whereas under NT, replicates of measured water contents and hydraulic properties showed a considerable large spatial variability. Simulations with time-constant hydraulic parameters led to underestimations of soil water dynamics in winter and early spring and overestimations during late spring and summer. The use of time-variable hydraulic parameters significantly improved simulation performance for all treatments, resulting in average relative errors below 13%. Since simulation results agreed with observed water dynamics in two seasons, the applicability of inversely estimated hydraulic properties for soil water simulations is demonstrated. Thus, simulations that address applied questions in agricultural water management may be improved by using time-variable hydraulic parameters. The simulated water balance indicated that RT and NT result in better water storage than CT and therefore may increase water efficiency under water-limited climatic conditions.     

大庆地区玉米出苗期土壤温度影响的试验研究——基于免耕覆盖技术

在黑龙江省大庆地区建立免耕覆盖对地温影响试验区,采用WQG-16型曲管地温表分别测定土壤地表下5cm和10cm两层温度,确定免耕覆盖对本地区玉米出苗期土壤温度的影响规律.结果表明:在5月20日前免耕覆盖(5～10cm)土层温度明显高于传统耕作,且其土壤温度比传统耕作早3天达到10℃以上;5月20日后传统耕作(5～10cm)土层温度高于免耕.     

Diesel oil consumption,work duration,and crop production of corn and durum wheat under conventional and no-tillage in southeastern France

In no-tillage (NT) system, precedent crop residue retains on the soil surface to preserve soil water for crop growth. In response to the negative impact of soil degradation under conventional tillage (CT) system based on soil tillage, NT system without tillage practice and with protective cover of crop residue is being developed in many parts of the world. However, NT is a successful system especially in the South of America, but the impacts of this system on the Mediterranean climate especially in the southeast (SE) of France is less known; therefore, this study has been carried out within the scope of a European project. Durum wheat and corn were sown under CT and NT. Time requirement and fuel consumption in these two systems were measured. The results showed that durum wheat and corn yields were the same in both systems except of 2008, while work duration and energy requirement were 87% and 83% lower in NT system, respectively. Furthermore, NT could mitigate CO₂ emission up to 50% as compared with CT. These results show that NT can be considered as a relevant alternative for CT regarding economical and environmental advantages.     

Impact of Tillage and Fertilizer Application Method on Gas Emissions in a Corn Cropping System

Tillage and fertilization practices used in row crop production are thought to alter greenhouse gas emissions from soil.This study was conducted to determine the impact of fertilizer sources,land management practices,and fertilizer placement methods on greenhouse gas(CO₂,CH₄,and N₂O)emissions.A new prototype implement developed for applying poultry litter in subsurface bands in the soil was used in this study.The field site was located at the Sand Mountain Research and Extension Center in the Appalachian Plateau region of northeast Alabama,USA,on a Hartsells fine sandy loam(fine-loamy,siliceous,subactive,thermic Typic Hapludults).Measurements of carbon dioxide(CO₂),methane(CH₄),and nitrous oxide(N₂O)emissions followed GRACEnet (greenhouse gas reduction through agricultural carbon enhancement network)protocols to assess the effects of different tillage(conventional vs.no-tillage)and fertilizer placement(subsurface banding vs.surface application)practices in a corn(Zea mays L.)cropping system.Fertilizer sources were urea-ammonium nitrate(UAN),ammonium nitrate(AN)and poultry litter(M)applied at a rate of 170 kg ha^-1 of available N.Banding of fertilizer resulted in the greatest concentration of gaseous loss(CO₂ and N₂O)compared to surface applications of fertilizer.Fertilizer banding increased CO₂ and N₂O loss on various sampling days throughout the season with poultry litter banding emitting more gas than UAN banding.Conventional tillage practices also resulted in a higher concentration of CO₂ and N₂O loss when evaluating tillage by sampling day.Throughout the course of this study,CH4 flux was not affected by tillage,fertilizer source,or fertilizer placement method.These results suggest that poultry litter use and banding practices have the potential to increase greenhouse gas emissions.     

Corn Yield and Nitrogen- and Water-Use under No-Tillage Rotations

Increased crop diversity and length of rotation may improve corn (Zea mays L.) yield and water- and nitrogen-use efficiency (WUE and NUE). The objectives of this study were to determine effects of crop rotation on corn yield, water use, and nitrogen (N) use. No-tillage (NT) crop rotations were started in 1997 on a Barnes clay loam (fine-loamy, mixed, superactive, frigid Calcic Hapludoll) near Brookings, S.D. Rotations were continuous corn (CC), corn–soybean [Glycine max (L.) Merr.] (CS), a 3-year rotation of corn–soybean–oat/pea (Avena sativa L. and Pisum sativum L.) hay (CSH), a 3-year rotation of corn–soybean–spring wheat (Triticum aestivum L.) (CSW), and a 5-year rotation of corn–soybean–oat/pea hay companion seeded with alfalfa (Medicago sativa L.)–alfalfa–alfalfa (CSHAA). Fertilizer N was applied to corn on all rotations at planting (16 kg N ha^?1) and side-dressed (64 kg N ha^?1). Average corn grain yields (1998–2007) were greatest under CSW (7.38 Mg ha^?1) and least under CC (4.66 Mg ha^?1). Yields were not different among CSH, CSW, and CSHAA rotations. Water-use efficiency of rotation was ordered as CSW > CSH > CSHAA > CS > CC. Nitrogen-use efficiency was greatest under CSW and least under CC. There were no differences in yield advantage (YA) among crop rotations during years with plentiful early-season rainfall (May 1–July 31). In years with low spring rainfall, YA was greatest under CSW (54%) and least under CSHAA (33%). Corn yields under extended rotations (CSH, CSW, and CSHAA) were greater than under CC and CS, but lack of rainfall may result in reduced yields under CSHAA.     

2BF-7型多功能免耕施肥播种机的研制

在分析传统播种机不适应我国北方干旱或半干旱地区施行保护性免耕施肥播种原因的基础上.针对存在的问题,采用种肥同沟施播的组合式开沟器来减少开沟器数量,改变铲柱一字形排列为三角形排列,改变开沟器安装形式加长铲柱高度等方法,并在新研制的2BF-7型多功能免耕施肥播种机上得以试验验证.结果表明,提供的方法可靠、有效,可供相关单位在开发新型免耕施肥播种机时参考借鉴.     

丘陵山区油菜免耕播种机的设计

采用免耕直播技术,在充分利用现有微耕机动力及行走机构的基础上,挂接油菜包衣种子播种器、施肥器和开沟部件,设计了2BM-4型油菜免耕播种机,并对其进行了田间播种试验。试验结果显示,2BM-4型油菜免耕播种机的播种均匀性好,能保证单位面积的基本苗数。2BM-4型油菜免耕播种机的研制既达到小型化的目的,又能提高现有微耕机的使用率。