Optimization of the Design of Subsoiling and Pressurized Fluid Injection Equipment

There are two different design objectives for subsoilers with pressurized fluid injection, for use as pan-breakers or injectors respectively. A large soil failure is desirable when it is used as a pan-breaker and little soil failure is advantageous when it is used as an injector. This paper determines optimum shapes of pan-breaker and injector, where the draught can be reduced by injecting pressurized air (about 1·2 MPa at the air tank) from a nozzle port at the tip of the chisel.The results show that the optimum pan-breaker with fluid injection should have a rake angle of 45 to 60°, a chisel thickness of 50 × 50 mm, and a heel position at 100 mm. The optimum injector with fluid injection should have a rake angle of 90°, a shank thickness of less than 15 mm, a chisel length of 250 mm, a chisel thickness of 30 × 30 mm, and a heel position at 100 mm.     

Force-Time Behaviour of Flat Tines in Dry Sand

Studies conducted in a laboratory soil bin filled with dry sand indicated that the nature of soil reactions on tines of 90° rake angle were cyclic for tine aspect ratios (width/depth) of 0·6 and greater. For tine aspect ratio of four, soil reactions were observed to be cyclic for all the tine rake angles studied (15-140°), These variations were found to be closely related to the observed soil failure patterns. Wave ratio (wave length/tine depth) for tines with a rake angle of 90° increased with increase in tine aspect ratio up to four. The amplitude of cyclic variations in draught increased with tine width for a rake angle of 90°.     

Tillage Tool Design by the Finite Element Method: Part 2. Experimental Validation of the Finite Element Results with Soil Bin Test

Laboratory soil bin tests of subsoiler cutting in a sandy loam soil were carried out in order to validate the results obtained from the finite element calculations reported in Part 1 of this study. Measured results of subsoiler draught force and soil failure dimension taken on the surface were presented for four combinations of the subsoiler shank rake angle and chisel angle. Soil bin tests also measured the variation of draught force with subsoiler displacement. It was observed that the angle of both the subsoiler parts affected the dimensions of the surface soil failure and the magnitude of subsoiler draught force.Finite element method predictions of the subsoiler draught force as well as the extent of surface soil failure agreed well with measurements made in the soil bin. The predicted draught force for all subsoiler types exceeded the measured ones. The overprediction error ranged from 11·76 to 20·04%. The finite element model provided a good approximation to the maximum upward soil movement for the experiments. Better finite element method predictions of the front soil failure was obtained for the two subsoiler designs with a small chisel angle of 15° than for the designs with chisel angles of 23 and 31°. Among the four investigated subsoiler types the best subsoiler design was devised, which required the lowest draught and developed good soil loosening qualities as estimated by soil volume change. This subsoiler had a shank of 75° rake angle and an inclined chisel of 15° angle. Keeping a good soil loosening performance was attributed to the smaller shank rake angle of 75°, which indicated that the shank played an important role for the determination of the quality of soil loosening.     

Centrifugation for separating piggery slurry 1. The performance of a decanting centrifuge

Odour nuisance arising from piggery slurry can be prevented by aeration. The stability of aerobically treated slurry, which is free of offensive odours, increases as the dry matter of the slurry decreases. This paper investigates the performance of a decanting centrifuge as one means of achieving a lower dry matter in piggery slurry.Slurry was centrifuged to show the effects of various operating conditions; 61% of the total solids were removed from slurry of 8% dry matter content wet basis (d.m.) in the form of fibrous solids of 27% d.m. and 43% of the total solids were removed from slurry of 2% d.m. as fibrous solids of 30% d.m. When the raw slurry had 8% d.m., centrifuging reduced the volume needed for liquid storage by 17%. A particle size analysis of the solids which remained in the centrifuged liquid showed that 98% were less than 0·020 mm diameter. This agrees with the predicted maximum size of particle left in the centrifuged liquid. Centrifuged liquid from the dilute slurry contained only 4% of particles greater than the predicted maximum diameter of 0·012 mm.     

Tillage Tool Design by the Finite Element Method: Part 1. Finite Element Modelling of Soil Plastic Behaviour

The finite element method calculations of draught and vertical forces, soil deformation and normal pressure distribution on subsoiler face were reported for four subsoiler types. A non-linear, three-dimensional, finite element analysis of the soil cutting process by a standard medium-deep subsoiler based upon the Drucker–Prager elastic-perfectly plastic material model was used. The mathematical construction of the Drucker–Prager model was presented. The material non-linearity of soil was dealt with using an incremental technique. Inside each step, the Newton–Raphson iteration method was utilized. The geometrical non-linearity was solved by using the small strain assumption. A comparison of subsoiler forces for calculations made with the small strain assumption and the updated Lagrange formulation of large displacement was reported for subsoiler cutting in a sandy soil. It was shown that the small strain assumption was more convenient for solving the geometrical non-linearity of a soil tilled down to relatively deep horizons.The theoretical results showed that a well coordinated angle combination of the two parts of the subsoiler made a large reduction in the draught and vertical forces of the subsoiler with a shank angle of 75° and a chisel angle of 15°. On the soil surface in front of the shank, the soil was deformed to produce a wedge-shaped soil upheaval. A maximum upward surface movement of 23·7 cm was calculated when soil tilling was performed with this design of subsoiler. For all the geometrical types of subsoiler studied, concentrations of normal pressure at the outer linking edges between the two parts of the subsoiler, as well as on the bottom corners of the chisel, indicated that during manufacturing these parts should be better supported against wear and deformation. The smallest chisel angle of 15° reduced considerably the pressure values at these two parts, whereas changing the shank rake angle from 90 to 75° only assisted in reducing the pressure values at the outer linking edges.     

A Novel Approach to the Prediction of Tillage Tool Draught using a Standard Tine

An investigation was conducted to develop and validate a novel approach to the prediction of the draught required by primary tillage implements op- erating in field conditions. A methodology was developed based upon an existing force prediction model which describes the draught of a standard tine as the product of two factors, related to soil strength and tool geometry respectively. The methodology results in a two-step prediction procedure, which consists of (1) establishing, in a reference soil condition, some comparative draught relationships (tool index I) be- tween the standard tine and each tillage implement and, (2) measuring the draught of the standard tine in the field. The tool index relationships were determined under laboratory conditions for a number of single tillage tools over a range of working depths, and the methodology was validated in four field conditions, namely: two friable sandy-loams, a compact clay and a plastic clay soil. Predicted draughts were on average within 18% of the measured values. In the friable soil conditions, the average prediction errors for the tine tools, mouldboard body and disc tool were 14%, 16% and 30% respectively. The corresponding errors for the same tools in the plastic clay were 18%, 26% and 26% respectively.     

马铃薯曲面式播种开沟器仿生设计与试验

针对马铃薯播种开沟器高速作业条件下作业阻力大、回土深度浅、干湿土易混合等问题,基于黄鳍金枪鱼下颚流线型曲线,采用水平直元线法将原有曲线重构为三维曲面,设计一种仿黄鳍金枪鱼下颚曲线的曲面式开沟器。根据马铃薯种植深度的农艺要求,当最大作业深度为150mm时,采用滑切原理确定了最大刃口角为132°,元线角为27°。为探究起土角对开沟器作业性能的影响,以作业阻力为评价指标,进行单因素试验,确定了分土板的起土角为45°。通过分析种薯下落到地表时的相对位移确定上挡土板的长度。干湿土分层仿真试验表明,开沟器作业不扰乱土层顺序。田间多工况对比试验表明,在开沟深度为100、125、150mm,作业速度为3.6、5.4、7.2km/h条件下,曲面式开沟器比芯铧式开沟器、靴式开沟器平均作业阻力减小18.3%、33.4%,平均回土深度增加70.4%、91.7%。田间性能对比试验表明,在开沟深度为150mm,作业速度为7.2km/h条件下,曲面式开沟器比芯铧式开沟器、靴式开沟器种沟中土壤含水率增加3.5%、4.7%,曲面式开沟器能减少干湿土混合,曲面式开沟器比芯铧式开沟器、靴式开沟器种薯横向偏移系数减小9.5%、10.1%,满足马铃薯种植开沟的农艺要求。     

Force Measurements on Driven Discs

Experiments were carried out under controlled conditions in a soil bin containing sandy-loam soil to study the effects of varying the speed ratio (ratio of peripheral disc speed to forward speed), disc angle and tilt angle settings, on the performance of adriven disc. The hydraulically powered disc provided speed ratios from −3 (backward) through approximately 1 (free wheeling) to 6 (forward). Disc angles were varied from 20 to 65°, from the direction of travel, and tilt angles from −15 to 30° with respect to the vertical. It was observed that there was a major reduction in draught force and specific draught resistance in all cases when disc speed increased from freely rotating to forward speed ratios of approximately 3. Driving a disc in the reverse direction reduced penetration resistance at certain angle settings. Backward-driven discs were also found to reduce side forces on the concave side of the disc and increase those on the convex side. Total power consumption and specific total power increased significantly when the disc was driven in either direction. The angle setting also affected the driven-disc performance. The optimum angle setting in terms of minimizing force and power requirements occurred at a disc angle between 35 and 50° with approximately 0° tilt angle. Observations of soil disturbance showed that driving a disc either backward or forward improved soil mixing and pulverization characteristics.     

北方典型污水处理厂污泥农用可行性分析

城市污泥中含有大量的植物营养元素,其农业利用能改善土壤的理化性质,提高作物产量,减少污泥对环境的二次污染,从而实现污泥的资源化、无害化、稳定化和减量化处置目标。为此,以北方四大典型污水处理厂的污泥为对象,对其2007-2008年的污泥数据进行统计并分析污泥中的主要成分,与国家污泥农用标准比较,判别污泥农用的可行性并提出合理化建议,以期为北方地区污泥合理地利用提供科学依据,探索经济有效的适合城市污泥处置与利用的有效途径。     

Deformation and Failure in Wet Clay Soil: Part 2, Soil Bin Experiments

Tests of soil cutting by wide tines were conducted in wet clay soil. Force-displacement curves were obtained and the soil deformation patterns were observed and analysed with the help of a painted grid. The tine experiment showed that the soil deformation pattern depended on the tool rake angle (the angle between the tine face and the horizontal soil surface). For small rake angles, soil deformed in a narrow zone leading up from the tool tip and there were tensile cracks near the tool tip. For bigger rake angles, soil in front of the tool failed by distortion with small shear lines and big soil-soil slip lines. For rake angles equal to or bigger than 90° an elliptical wedge formed. Passive earth pressure theory did not describe the deformations observed in these wet clay soil conditions.     

Use of sub-hourly soil water content measured with a frequency-domain reflectometer to schedule irrigation of cabbages

Laboratory and field measurements of soil water content were obtained using gravimetric and Theta-Probe methods, the latter a frequency-domain reflectometry method. We obtained real-time in situ measurements of soil water content at depths of 30, 80, 160, 240 and 350 mm to evaluate irrigation practice. A datalogger recording the change in soil water content (and cumulative irrigation) at 20-min intervals was used, with appropriate calculations and graphical presentation, to predict the time and amount of irrigation water required for soil water content to reach field capacity. Measurements at three instead of five depths yielded a different depth-averaged soil water content under relatively dry conditions (less than 0.273 m³ m⁻³), and predicted a later start for irrigation and early crop water stress. Investing in additional sensores for scheduling irrigation would be compensated by financial resources saved through avoiding excess or deficit irrigation, and the associated application cost, loss of nutrients and soil due to deep percolation and erosion, and loss of crop production.     

沼液灌施对潮土土壤团聚体组成及稳定性的影响

[目的]探究沼液灌施对黄淮海平原土壤团聚体结构的影响.[方法]以黄淮海平原潮土为研究对象,根据等氮量原则,采用干湿筛法对连续4a进行沼液灌施(BS)、化肥施用(CF)、沼液与化肥灌施(BS+CF)以及空白对照(CK)共4种处理的农田表层土壤(0～20cm)进行团聚体筛分并计算稳定性指标.[结果]沼液灌施影响黄淮海平原表...     

无驱动式自动调平水田埋秆起浆整地机设计与试验

为解决东北稻区秸秆全量还田条件下,现有驱动式搅浆机存在动力消耗大、严重破坏土壤结构并使得秸秆漂浮等问题,设计了一种无驱动式自动调平水田埋秆起浆整地机,机具前排星形耙片细碎土壤并掩埋秸秆,后排轧滚进一步碎土埋秆,平地装置平整地表,由电液控制系统实现自动调平,能够为水稻插秧作业创造优良地块条件。通过理论分析和优化设计,确定了优化后星形耙片的各项结构参数和排列方式;设计了带有齿板和刀齿的轧滚,倾斜布置的齿板和直立的刀齿分别对土壤进行横向与纵向的滑切,可提高碎土埋秆效果;改进设计了平地板,〖JP2〗确定了板高为150mm,并针对前进速度、板宽、推压角开展了仿真试验,得到最优工作参数为：前进速度2.4km/h、板宽290mm、推压角44°;采用中心不动法的调平策略,设计了基于倾角传感器和PID算法的自动调平电液控制系统,实现了自动调平系统的快速平稳控制。田间试验结果表明,整机作业后地表平整度为0.73cm,秸秆覆盖率为91.4%,压茬深度为5.98cm,泥浆度为1.18g/cm3,机具各项指标均优于国家标准,该设计可为东北稻区秸秆全量还田条件下水整地机具研究提供参考。     

Influence of irrigation water quality on soil infiltration

The quality of municipal waste water is affected by its chemical composion and by the process used to treat it. If suspended solids limit infiltration, their removal by the municipal treatment facility is a factor to consider in the planning and management of water resources. The effect of water quality and sprinkler water application rate on bare soil infiltration was investigated. Treated wastewater and clean water were applied to a bare soil at two different application rates, 25 mm/hr and 100 mm/hr. The change in each soil infiltration rate after eight runs for each water quality was determined. The results showed that the reduction in infiltration rate was greatest for the soil under the treated wastewater application due to the effect of accumulation of suspended solids at the soil surface.     

立旋式驱动型联合整地机的设计与试验

针对新疆常规联合整地机对黏重土壤播前整地作业耙深稳定性差、碎土率低及地表平整度低等问题,在结合新疆农业对播前整地作业要求、土壤特性等因素的基础上,设计了一种立旋式驱动型联合整地机,并完成整机的加工试制.通过对关键零部件的设计及理论分析,确定了传动系统、平土杠和钉齿镇压辊等零部件的结构参数,并通过运动分析确定耙齿转速为4...     

施灌沼肥对土壤氨挥发和氮素下渗规律的影响

为探讨施灌沼肥对土壤氨挥发和氮素下渗的影响,在室温条件下,采用土柱模拟试验,系统研究沼肥不同施用量和不同施用深度对土壤表面的NH3挥发及土壤垂直剖面上的总氮、NH+4-N、NO-3-N下渗的影响规律。结果表明:表施沼肥时,土壤表面的NH3挥发累积量和挥发的延续时间均随沼肥施用量的增加而增加;土壤垂直剖面上的含水率、总氮和NH+4-N均主要集中在表层土壤,而NO-3-N可迁移至较深层土壤。底施沼肥时,NH3挥发累积量随着沼肥施用深度的增加而减少,施用深度为10 cm时便可有效减少沼肥的NH3挥发损失;同时土壤垂直剖面上的含水率和总氮、NH+4-N、NO-3-N质量比的最高点均与沼肥施用深度呈显著正相关。     

生物炭配施沼液对土壤团聚体及其有机碳分布的影响

【目的】探究生物炭与沼液配施的最优组合,为农田合理施肥提供科学依据。【方法】基于3 a(2017―2019年)田间定位试验,设置CK、单施生物炭(12 t/hm2)、3个水平沼液(沼液∶水分别为1∶6、1∶4和1∶2)和生物炭分别与3个水平沼液配施,共计8个处理,利用湿筛法测定了土壤团聚体分布和有机碳质量分数。【结果】生物炭和沼液配施能有效提高>0.25 mm粒级的土壤水稳性团聚体质量分数,较CK增加幅度为13.0%～36.3%;各施肥处理不同程度地提高了土壤团聚体的平均重量直径(MWD)和几何平均直径(GMD),增加幅度分别为9.8%～39.3%和10.0%～37.5%,沼液配比为1∶4时生物炭配施沼液对团聚体MWD值和GMD值影响最大;施肥处理各粒级团聚体有机碳质量分数显著高于CK,生物炭配施沼液的效果要优于单施生物炭或沼液处理。有机碳与>0.25 mm粒级的团聚体质量分数、MWD值和GMD值均呈极显著正相关关系。同时,各施肥处理降低了土壤体积质量,最大降幅为6.7%。添加生物炭和猪场沼液对提高土壤团聚体稳定性和改善土壤结构有积极作用。【结论】从提高土壤质量和资源高效利...     

Soil water storage and surface runoff as influenced by irrigation method in arid soils with surface crust

The effects of irrigation methods, application rates and initial moisture content on soil water storage and surface runoff were studied in soils liable to surface crust formation during 1995–1996 at the University of Jordan Research Station near Al-Muwaqqar village. Four irrigation methods were tested (sprinkler, furrow, basin and trickle) and four application rates (6.2, 14.4, 24.4 and 28.4 mm/h). Two runs were performed (soil initially dry and soil initially wet). Basin irrigation provided the highest application efficiency followed by trickle, sprinkler and furrow irrigation methods. Entrapping water by the basin borders increased soil water storage by allowing more water to infiltrate through the surface crust. Decreasing the application rate from 28.4 to 6.2 mm/h increased soil water storage significantly in all 150 mm layers to a depth of 600 mm. If the soil was already wet, soil moisture storage decreased owing to siltation during the prewetting and formation of a surface crust and low soil water storage capacity. A sedimentary crust formed at the bottom of the furrows in the furrow irrigation treatment, which reduced soil water storage and increased surface runoff significantly owing to the reduction in infiltration. Increasing the application rate from 6.2 to 28.4 mm/h in the furrow surface irrigation treatment increased the runoff discharge 10-fold. Even with the lowest application rate the runoff coefficient under sprinkler irrigation was 20.3% indicating high susceptibility of Al-Muwaqqar soils to surface crust formation.     

机械化旱作节水技术的应用

彰武县是典型的北方旱作农业区,旱灾频繁,全县绝大部分耕地无水浇条件。详细介绍秸秆覆盖及高留茬、机械化深松及重耙压、地膜覆盖3项技术的内容和效果,通过多种作业模式的机械化旱作节水技术集成示范基地建设项目,探索旱作条件下依靠天然降水实现大面积旱作农田保土保肥、抗旱保水节水、增产增收的有效途径。     

Centrifugation for separating piggery slurry 3. Economic effects on aerobic methods of odour control

The costs of reducing the odours from piggery slurries to an inoffensive level and storing that slurry in an inoffensive state are discussed. Five different combinations of aerobic treatment and separation for slurries containing initially between 1·5 and 8% d.m., from 2000 and 8000 pigs, and with storage for five days or 30 days are considered. The five combinations are aeration of raw slurry; separation then aeration; centrifugation then aeration; aeration of raw slurry then centrifugation; and separation then aeration then removal of more solids by centrifugation. The costs of storing the effluents from these processes are also included.For slurry from the smaller herd and for a short storage period, the cost of aerobic treatment of raw slurry is lower than other treatments when the slurry is less than 4·5% d.m. Using a brushed screen/roller press separator to remove solids before aeration produces the cheapest control of odours for slurries above 4·5% d.m.When 30 days' storage or more is required, separation before aeration is cheaper for slurries with more than 3% d.m. and the costs of using a decanting centrifuge (costing £38 000) before aeration is similar to aerating raw slurry at 6% d.m.With a large (8000 pig) herd, using the centrifuge before aeration to produce slurry that is inoffensive for 30 days is the cheapest method at all dry matter contents. When storage is required for only five days, separation or centrifugation before aeration have similar costs, these costs are similar to the cost of aerating raw slurry when it contains less than 3% dry matter, but as dry matter content of the raw slurry increases the cost rises steeply. Removing solids from slurry by centrifugation after aeration increases the overall costs compared to aerating raw slurry.