Effects of Subsoiling on Soil Moisture Under No-Tillage for Two Years

In order to improve the water use efficiency under conservation tillage, the effects of subsoiling on soil moisture under notillage were studied. An experiment of 40 cm subsoiling in a field kept under no-tillage for 2 years was operated from 2005 to 2006. Based on the data of the soil moisture and crop yield, the physical basis of subsoiling for water conservation and yield increase was analyzed. The results showed that the soil water storage under subsoiling, from the soil surface to a depth of 100 cm was more than that under no-tillage for the growth season. In the 0-100 cm soil depth, the soil moisture in 50-100 cm depth under subsoiling was more compared with no-tillage, which increased when it＇s drought and decreased when it＇s rainy with the increase in soil depth. Compared with no-tillage, subsoiling could reduce the water consumption of oats in the 0-50 cm depth and increase the water consumption in the 50-100 cm depth. Also, subsoiling increased the yield by 18.29% and the water use efficiency by 16.8% in a two-year average. The effects of subsoiling on water conservation and yield increase were affected by precipitation, and a well-proportioned rainfall was better to increase yield and water use efficiency. Meanwhile, subsoiling decreased bulk density, which increased with the available precipitation. Subsoiling under no-tillage is the effective rotation tillage to contain more soil moisture and improve water use efficiency in ecotone of North China.

Characterization of Leaf Photosynthetic Properties for No-Tillage Rice

A study was conducted to determine the influence of no-tillage cultivation on leaf photosynthesis of rice plants under field conditions. Experiments with the treatments, no-tillage and conventional tillage were carried out at three locations （Jiaxing, Hangzhou and Xiaoshan, Zhejiang Province, China） for two years （2005 and 2006）. Grain yield was constant in Jiaxing, but slightly higher in Hangzhou and Xiaoshan under no-tillage cultivation than that under conventional cultivation. In comparison with the conventional cultivation, no-tillage cultivation showed less biomass accumulation before heading and higher capacity of matter production during grain filling. A significantly higher leaf net photosynthetic rate was observed for the plants under no-tillage than for those under conventional tillage. The fluorescence parameter （Fv/Fm） in leaf did not show any difference between the two cultivations. The effect of cultivation management on transpiration rate （Tr） and SPAD value of rice leaf was dependent on the location and year.

Inter-annual changes in the aggregate-size distribution and associated carbon of soil and their effects on the straw-derived carbon incorporation under long-term no-tillage

Converting from conventional tillage to no-tillage influences the soil aggregate-size distribution and thus soil organic carbon （SOC） stabilization. However, the dynamics of soil aggregation and the straw-derived carbon （C） incorporation within aggregate fractions are not well understood. An experiment was established in 2004 to test the effects of two treatments, no-tillage with residue （NT） and conventional tillage without residue （CT）, on the soil aggregate-size distribution and SOC stabilization in a continuous maize （Zea mays L.） cropping system located in the semiarid region of northern China. Soil samples were collected from the 0-10 cm layer in 2008, 2010 and 2015, and were separated into four aggregate-size classes （〉2, 0.25-2, 0.053-0.25, and 〈0.053 mm） by wet-sieving. In each year, NT soil had a higher proportion of macroaggregates （i.e., 〉2 and 0.25-2 mm） and associated SOC concentration compared with CT. Additionally, to compare straw-derived C incorporation within NT and CT aggregate fractions, ^13C-labeled straw was incubated with intact NT and CT soils. After 90 days, the highest proportion of 13C-labeled straw-derived C was observed in the 〉2 mm fraction, and this proportion was lower in NT than that in CT soil. Overall, we conclude that long-term continuous NT increased the proportion of macroaggregates and the C concentration within macroaggregates, and the physical protection provided by NT is beneficial for soil C sequestration in the continuous maize cropping system in semiarid regions of northern China.

Effect of experimental warming on soil respiration under conventional tillage and no-tillage farmland in the North China Plain

Understanding the response of soil respiration to global warming in agro-ecosystem is crucial for simulating terrestrial carbon （C） cycle. We conducted an infrared warming experiment under conventional tillage （CT） and no-tillage （NT） farmland for winter wheat and summer maize rotation system in North China Plain （NCP）. Treatments include CT with and without warming （CTW and CTN）, NT with and without warming （NTW and NTN）. The results indicated that warming had no sig- nificant effect on soil moisture in irrigated farmland of NCP （P〉0.05）. The elevated average soil temperature of 1.1-116℃ in crop growing periods could increase annual soil CO2 emission by 10.3% in CT filed （P〉0.05）, but significantly increase it by 12.7% in NT field （P〈0.05）, respectively. The disturbances such as plowing, irrigation and precipitation resulted in the obvious soil CO2 emission peaks, which contributed 36.6-40.8% of annual soil cumulative CO2 emission. Warming would enhance these soil CO2 emission peaks; it might be associated with the warming-induced increase of autotrophic respiration and heterotrophic respiration. Compared with un-warming treatments, dissolved organic carbon （DOC） and soil microbial biomass carbon （MBC） in warming treatments were significantly increased by 11.6-23.4 and 12.9-23.6%, respectively, indicating that the positive responses of DOC and MBC to warming in both of two tillage systems. Our study highlights that climate warming may have positive effects on soil C release in NCP in association with response of labile C substrate to warming.

Growth Characteristics and Yield of Late-Season Rice under No-tillage and Non-flooded Cultivation with Straw Mulching

A long-term field experiment （started at 2003） was conducted to determine the effects of different dce cultivation methods on growth characteristics and grain yield of late-season rice under double-rice cropping system in seasonal drought region of southeast China （Yujiang County, Jiangxi Province）. The rice cultivation methods included no-tillage and flooded rice cultivation （N-F）, no-tillage and non-flooded rice cultivation with straw mulching （N-SM）, and no-tillage and non-flooded rice cultivation without straw mulching （N-ZM）. There was no significant difference in rice grain yield between the N-SM and N-F treatments. However, the rice grain yields in the N-SM and N-F treatments were significantly higher than that in the N-ZM treatment. The late-season rice plants in the N-SM treatment had significantly higher numbers of effective panicles and total grains per hill compared with those in the N-ZM treatment. The above-ground dry matter of late-season rice was similar between the N-SM and N-F treatments. Compared with the N-F treatment, the N-ZM and N-SM treatments significantly decreased the leaf area at the heading stage. Moreover, the N-SM treatment could significantly increase total root length and root tip number at the grain-filling stage compared with the N-ZM treatment.

Suppression of weeds and weed seeds in the soil by stubbles and no-tillage in an arid maize-winter wheat-common vetch rotation on the Loess Plateau of China

Reduced tillage provides ecological and economic benefits to arable land on the Loess Plateau of China, where soil erosion has long been a serious problem and soil water availability is largely restricted. However, high abundances of weeds in reduced tillage systems cause significant yield losses. In this study, we explored the effects of no-tillage and stubble retention on the number and density of weeds and weed seeds in a 12-year maize-winter wheat-common vetch rotation on the Loess Plateau. Four treatments including conventional tillage, no-tillage, conventional tillage＋stubble retention and no-tillage＋stubble retention were designed and applied. We found that no-tillage increased the number of weed species and weed density in most of the crops, while stubble retention decreased weed density in maize and tended to suppress weeds in both no-tillage treatments（no-tillage and no-tillage＋stubble retention）. No-tillage led to an increase in the number of weed species in the weed seedbank and tended to increase seed density during the spring growth of winter wheat, but it decreased seed density during post-vetch fallow. Stubble retention tended to reduce seed density during the spring growth of winter wheat and post-vetch fallow. We concluded that no-tillage can promote weeds in the experimental crop rotation, while stubble retention suppresses weeds in untilled fields. The combined effects of stubble retention and no-tillage on weed suppression varied among the three crops. Based on these results, we recommend stubble retention in untilled legume-crop rotations on the Loess Plateau to improve the control of weeds.

Long-Term No-Tillage Direct Seeding Mode for Water-Saving and Drought-Resistance Rice Production in Rice-Rapeseed Rotation System

To study the effects of long-term no-tillage direct seeding mode on rice yield and the soil physiochemical property in a rice-rapeseed rotation system, a comparative experiment with a water-saving and drought-resistance rice （WDR） variety and a double low rapeseed variety as materials was conducted under no-tillage direct seeding （NTDS） mode and conventional tillage direct seeding （CTDS） mode for four years, using the CTDS mode as the control. Compared with the CTDS mode, the actual rice yield of WDR decreased by 8.10% at the first year, whereas the plant height, spikelet number per panicle, spikelet fertility, 1000-grain weight, grain yield, actual yield, and harvest index increased with no-tillage years, which led to the actual yield increase by 6.49% at the fourth year. Correlation analysis showed that the panicle length was significantly related to the actual yield of WDR. Compared with the CTDS mode in terms of the soil properties, the pH value of the NTDS mode decreased every year, whereas the contents of soil organic matter and total N of the NTDS mode increased. In the 0-5 cm layer of the NTDS mode, the soil bulk decreased, whereas the contents of soil organic matter, total N, and available N increased. In the 5-20 cm layer of the NTDS mode, the available N and K decreased, whereas the soil bulk, contents of soil organic matter, and total N increased. In summary, the NTDS mode increased the rice yield, and could improve the paddy soil fertility of the top layer.

No-tillage effects on grain yield and nitrogen requirements in hybrid rice transplanted with single seedlings: Results of a long-term experiment

This study was conducted to determine whether,and if so how,the grain yield and nitrogen(N) requirements of hybrid rice transplanted as single seedlings are affected by no-tillage(NT) practices.A fixed field experiment was done at the Experimental Farm of Hunan Agricultural University in Changsha,Hunan Province,China,from 2004 to 2014.Grain yield and yield attributes(panicle number per m2,spikelet number per panicle,spikelet filling percentage,grain weight,total biomass,and harvest index) were evaluated as well as the N-use characteristics(total N uptake,internal N-use efficiency,and N requirements) of hybrid rice transplanted as single seedlings comparing NT with conventional tillage(CT).A significant finding was that there were no significant differences in grain yield,yield attributes,and N-use characteristics between CT and NT.Averaged across the 11 years,grain yield and N requirements were 9.51 t ha^(-1) and 20.2 kg t^(-1) under CT and 9.33 t ha^(-1) and 20.0 kg t^(-1) under NT,respectively.There were significant yearly variations in grain yield,yield attributes,and N-use characteristics observed under both CT and NT.The yearly variation in grain yield was related to simultaneous changes in spikelet number per panicle,grain weight,total biomass,and harvest index.Also,it was found that grain yield was positively correlated with internal N-use efficiency but negatively correlated with N requirements.It is concluded that grain yield and N requirements in hybrid rice when transplanted as single seedlings are not affected adversely by NT.The results of this study suggest that(1) compatible relationships among yield attributes can be established in hybrid rice that is transplanted as single seedlings,and(2) higher grain yield and higher N-use efficiency can be concurrently achieved in hybrid rice transplanted as single seedlings.

Physiological Mechanism of High and Stable Yield of No-tillage Cast-transplanted Rice

Four years' successive comparative experiments showed that no-tillage cast-transplanted rice (NTCTR), compared with conventional tillage cast-transplanted rice (CK), grew slower and produced less tillers at the early growing stage; but, it had shorter ineffective tillering time, less nutrition consumption, stronger individual growth and more uniform growth between individuals and the colony. These characteristics contribute to the increase not only in the productive tiller percentage but also in the ear quality. Furthermore, the flag leaf of NTCTR had higher photosynthetic rate during the filling stage and no early senescence phenomenon at the late stage, which facilitated the accumulation and the transportation of carbohydrates and improved grain setting rate.

Effects of Five Years Adoption of No-Tillage Systems for Vegetables Crops in Soil Organic Matter Contents

Vegetables productions systems are done normally with intense soil tillage causing a strong decline of soil quality. Use of conservation systems can be an alternative to recover this quality. In order to evaluate the effects of such systems on soil organic matter, an experiment has been conducted in randomized blocks design and factorial scheme 3 × 2: three soil management systems (no-tillage;reduced tillage and conventional tillage) and two cover crops (maize single;and intercropping maize with gray velvet bean—Stizolobium niveum);and repeated measures over time. Soil samples were collected before the implementation of the experiment and at the end of each crop cycle until the fifth crop cycle. Carbon associated with humic substances is also determined in 0 - 5 cm, 5 - 10 cm and 10 - 30 cm at the end of the last crop cycle. The SOM content was higher in RT (48.34 g·kg-1) than in the CT (39.48 g·kg-1) at the end of the fifth crop cycle. SOM content in NT (44.92 g·kg-1) was statistically equal to RT and CT, during the same period. In 0 - 5 cm, carbon contents associated to the humic substances present the same behavior of SOM contents in 0 - 10 cm. Probably these results are associated with the capacity of each system to improve superficial contents of SOM stable fractions. It follows that the conservation systems used are alternatives to the cultivation vegetables in order to improve soil organic matter contents.

Increasing the appropriate seedling density for higher yield in dry direct-seeded rice sown by a multifunctional seeder after wheatstraw return

Dry direct-seeded rice(DDR) sown using a multifunctional seeder that performs synchronous rotary tillage and sowing has received increased attention because it is highly efficient,relatively cheap,and environmentally friendly.However,this method of rice production may produce lower yields in a rice–wheat rotation system because of its poor seedling establishment.To address this problem,we performed field experiments to determine the rice yield at five seedling density levels(B1,B2,B3,B4,and B5=100,190,280,370,and 460 seedlings m-2,respectively) and clarify the physiological basis of yield formation.We selected a representative high-quality rice variety and a multifunctional seeder that used in a typical rice–wheat rotation area in 2016 and 2018.The proportion of main stem panicle increased with increasing seedling density.There was a parabolic relationship between yield and seedling density,and the maximum yield(9.34-9.47 t ha-1) was obtained under B3.The maximum yield was associated with a higher total spikelet number m-2 and greater biomass accumulation from heading to maturity.The higher total spikelet number m-2 under B3 was attributed to an increase in panicle number m-2 compared with B1 and B2.Although the panicle numbers also increased under B4 and B5,these increases were insufficient to compensate for the reduced spikelet numbers per panicle.Lower biomass,smaller leaf area,and lower N uptake per plant from the stem elongation stage to the heading stage were partially responsible for the smaller panicle size at higher seedling density levels such as B5.The higher biomass accumulation under B3 was ascribed to the increases in the photosynthetic rate of the top three leaves m-2 of land,crop growth rate,net assimilation rate,and leaf area index.Furthermore,the B3 rice population was marked by a higher grain–leaf ratio,as well as a lower export ratio and transport ratio of biomass per stem-sheath.A quadratic function predicted that 260-290 seedlings m-2 is the optimum seedling density for achieving maximum yield.Together,these results suggested that appropriately increasing the seedling density,and thereby increasing the proportion of panicles formed by the main stem,is an effective approach for obtaining a higher yield in DDR sown using a multifunctional seeder in a rice–wheat rotation system.

基于PLC技术的播种机电气自动化技术探究

以进一步提升小麦播种机的作业控制精度及综合播种效率为目标,选取电控单元为改进设计出发点,基于PLC与电气控制技术展开布局设计与应用探究。结合小麦播种所要达到的作业标准及其结构组成特点,建立用于实现精准智能控制的理论计算模型,并进行规范的PLC自动控制程序设计与电气组件配置,形成高质量的全闭环自动播种系统,展开PLC电气控制下的播种作业性能验证。试验结果表明:基于PLC技术的小麦播种机结构控制改进设计,可令播种控制准确率与播种合格率同步得到显著提升,重播率与漏播率分别可控制在5.26%与3.37%,整机播种作业试验效果良好,具有很强的实践推广性,可为类似播种农机智能化的发展提供借鉴与参考。

育种播种机钢索复卷测程装置的结构设计与试验

目前,小区育种播种机定长获取方式主要通过人工测量,效率低且作业强度大,严重制约了小区育种机械的快速发展。为此,设计了一种钢索复卷测程装置,采用自动收放式测程,通过探测装置检测钢索固定的钢制或橡胶等材质球体获取小区育种播种机区间位置数据信号。为了确定不同前进速度下钢索复卷测程装置连续工作的合理参数范围,通过样机试验对装置进行参数优化。试验结果表明:往复导线轮V型角度在10°~20°之间,往复丝杠长度在400~450mm之间,装置运行稳定且无钢索缠绕和收排线集中等问题,带有触点式的行程开关的信号传输和控制运行稳定可靠,达到了育种播种机测程的要求。

俯仰式播种单体仿形性能检测试验台设计与试验

为解决播种单体仿形机构性能难以检测的问题,设计了俯仰式播种单体仿形性能检测试验台。阐述了试验台组成结构与工作原理,对其高速传动系统、液压升降系统、监控系统以及关键部件参数进行设计。应用ANSYS软件对台架整体和关键部件进行静力学分析和模态分析,验证结构设计的合理性。为检验俯仰式播种单体仿形性能检测试验台的实际检测效果,以德邦大为1205型牵引式免耕精量播种机播种单体为研究对象,先以液压杆伸出量与传送带速度为试验因素,以监控系统误差为评价指标进行试验。试验得出,在液压杆伸出量为0~200 mm范围内,监控系统角度传感器最大误差为0.69 mm;在传送带速度8~19 km/范围内,光电编码器最大误差为0.18 km/h。确认监控系统准确性后,再以单体速度为试验因素,采集速度8、10、12 km/h下地块的起伏数据为目标曲线,以地形起伏模拟曲线的绝对误差平均值为指标进行单因素试验,试验得出,所设计的试验台可有效模拟田间地面的起伏频率与起伏量,绝对误差平均值为1.86 mm,满足播种单体仿形性能检测需求。

多重扰动清种式大蒜单粒取种排种器设计与试验

针对勺链式大蒜播种机取种过程中常出现的漏种、重种问题,设计了一种多重扰动清种式大蒜单粒取种排种器。取种勺在充种阶段获取多粒蒜种,经多重扰动清种,最终取种勺内仅余1粒蒜种。本文以金乡蒜种为研究对象,阐述了排种器的工作原理,确定了排种器的各项参数和多重扰动装置的最佳安装位置。通过DEM-MBD耦合仿真试验,分析了倾斜角、取种勺线速度对充种成功率的影响,以及凹槽形状对单粒取种率的影响。运用Box-Behnken中心组合试验方法,以第2弧形突出部分坡度、倾斜角、取种勺线速度为试验因素,以单粒取种率和漏种率作为评价指标,开展了三因素三水平正交试验。利用Design-Expert 8.0.6数据分析软件,分析了各因素对单粒取种率与漏种率的影响,对试验因素进行优化,确定了多重扰动装置最佳结构参数。设计试验台对仿真结果进行验证,倾斜角、取种勺线速度分别为15°、0.07 m/s的条件下,通过调节多重扰动装置与取种勺凹槽顶端距离适配不同级别蒜种,当Ⅰ级、Ⅱ级、Ⅲ级蒜种距离分别为0、6.1、12.1 mm时,单粒取种成功率分别为92.2%、97.2%、95.6%,具有良好的取种性能。

玉米免耕播种机振动特性及对排种器排种性能的影响

为研究玉米免耕播种机振动特性以及振动对排种器漏播指数和重播指数的影响,搭建一套由振动加速度传感器、电荷放大器、USB采集卡组成的播种作业振动测试系统,在玉米免耕播种机免耕地表作业时进行振动测试采集播种作业的振动信号。因田间工作环境复杂,使用经典滤波法中的IIR滤波器滤除所采集振动信号中其他高频干扰信号,对田间采集振动信号进行时域分析,均方值作为时域分析指标值。结果表明:振动加速度均方根随着作业速度和旋耕机转速的增加呈线性增加,旋耕机转速和作业速度是引起玉米免耕播种机振动的主要因素,影响顺序为:旋耕机转速>作业速度。使用二次积分法对田间采集信号进行分析,得出播种机作业时最大振动位移为16.004mm,对振动信号进行频域分析,使用直接法求出功率谱密度。结果表明:玉米免耕播种机振动频率主要在0~100Hz之间,频率分布与旋耕机转速影响较大。根据田间振动信号所得工作参数搭建振动试验台,以播种机振动频率、振动幅值、作业速度为试验因素,合格指数、漏播指数为评价指标进行3因素3水平响应面试验。结果表明:作业速度、振动幅值和振动频率对合格指数和漏播指数影响较为显著。各因素对合格指数影响顺序为:振动幅值、作业速度、振动频率;各因素对漏播指数影响顺序为:振动幅值、振动频率、作业速度。研究结果可为降低玉米免耕播种机振动和优化指夹式排种器提供理论参考。

3D建模在播种机产品设计上三维艺术仿真

以SolidWorks2015仿真软件设计播种机为例,通过引入三维艺术,完成了播种机零部件结构的设计,并通过修改零部件特征完成了播种机3D模型和整机装配。经过SolidWorks 3D虚拟建模和装配,得出了如下结论:利用Solidworks2015对播种机进行3D建模和装配,符合播种机实际生产制造流程。

基于预知维修的小麦播种机运行监控系统设计

为了减少播种机故障频率,提升小麦播种机的播种效率和播种质量,基于预知维修对小麦播种机的运行监控系统进行了设计。系统的主要组成包括主控单片机、检测系统、显示监控系统、报警系统及电源。为了对播种机进行预知维修,将灰色模型和神经网络模型结合,建立了动态灰色神经网络模型,并进行了算法设计。为了验证小麦播种机监控系统性能和预知维修算法的有效性,对其进行了监测精度和趋势预测试验,结果表明:监测系统的监测精度较高,播种机可有效对数据趋势进行预测。

基于机器深度学习的小麦播种机控制系统研究

针对我国小麦播种机自动控制系统的可靠性及灵敏度不高的问题,基于机器深度学习对小麦播种机的控制系统进行了设计和改进。小麦播种机的主要组成包括控制系统、排种系统、监控系统、电力系统、机架和驾驶室、覆土镇压和排肥装置。为了使播种机的控制系统能有效进行图像检测识别,提升播种机的控制精度,采用机器深度学习中的卷积神经网络算法对控制系统进行设计,并采用迁移学习的方式对模型进行训练和检测。为了验证播种机控制系统的性能,对其进行播种精度控制和播种性能测试试验,结果表明:播种机的精度和性能均符合播种机的设计要求。

基于智能逆变技术的玉米精播机性能优化

为进一步提升我国玉米精播机的综合作业效率,以性能优化提升作为研究目标,基于智能逆变技术的深度应用展开分析。以电控逆变处理与调速机制相融合为出发点,建立正确的电控模块逆变应用数学模型,通过控制分析与硬件优化,进行整机作业试验。结果表明:基于智能逆变技术应用的玉米精播机性能优化效果明显,排种精准率与播深合格率分别可提升至94.46%与94.05%,满足精量播种机的设计要求;同时,种子的重播率与漏播率可降低至3.83%与3.06%,整机作业运行稳定,各零部件指令执行协同性好,综合效率相对提升了5.88%,充分体现了智能逆变应用的准确性与适应性,可为类似农机播种装备优化提供参考。